rexresearch
rexresearch1
Flash Joule Heating
https://metalliuminc.com/flash-joule-heating
What Is Flash Joule Heating? Unleashing Instantaneous Heat
Flash Joule Heating is an innovative technology that utilizes the principle of electrical resistance to generate intense heat within materials almost instantaneously.
This process involves passing a direct current through a material, where the resistance of the material itself converts electrical energy into heat energy. The result is a rapid increase in temperature, often exceeding 3,000 degrees Celsius in milliseconds —
a phenomenon known as 'flashing'.
https://news.rice.edu/news/2025/rapid-flash-joule-heating-technique-unlocks-efficient-rare-earth-element-recovery
Rapid flash Joule heating technique unlocks efficient rare earth element recovery from electronic waste
Shichen Xu Justin Sharp, Bing and James M. Tour
Sustainable separation of rare earth elements from wastes
Significance
Our study presents a flash Joule heating (FJH) combined with chlorination (FJH-Cl2) as an efficient method for rare earth elements (REE) separation and recovery from electronic waste. FJH-Cl2 enables high-purity (>90%) and high-yield (>90%) REE recovery from waste magnets in a single step, reducing energy consumption by 87%, greenhouse gas emissions by 84%, and operating costs by 54% while eliminating water and acid use by 100% compared to traditional hydrometallurgical methods.
Abstract
Rare earth elements (REEs) are indispensable in modern technologies, but their supply chain faces challenges due to limited geographical availability and political difficulties. Recycling REEs from industrial waste provides a sustainable alternative to mining, promoting a circular economy and reducing environmental impacts. The mainstay approaches for REE recovery, hydrometallurgical and pyrometallurgical methods, can be inefficient, consuming high energy and generating large aqueous and acid waste streams. Here, we introduce flash Joule heating (FJH) combined with chlorination (FJH-Cl2) as an efficient method for REE separation and recovery by capitalizing on the free energies of formation (ΔGform) of the metal chlorides and the boiling points of those metal chlorides. FJH-Cl2 enables high-purity (>90%) and high-yield (>90%) REE recovery from waste magnets in a single step. Life cycle assessment and techno-economic analysis show that this process reduces the number of steps by 3× while reducing energy consumption by 87%, greenhouse gas emissions by 84%, and operating costs by 54% while eliminating water and acid use by 100% compared to traditional methods. This offers an environmentally friendly and economically viable pathway for sustainable REE recycling and recovery.
https://www.youtube.com/watch?v=qUjvkl7aBns
Flash Joule heating by Rice lab recovers precious metals from electronic waste in seconds
Rice University
https://pubs.acs.org/doi/10.1021/jacs.4c02864
Electric Field Effects in Flash Joule Heating Synthesis
...While traditional methods of graphene synthesis involve purely chemical or thermal driving forces, our results show that the presence of charge and the resulting electric field in a graphene precursor catalyze the formation of graphene. Furthermore, modulation of the current or the pulse width affords the ability to control the three-step phase transition of the material from amorphous carbon to turbostratic graphene and finally to ordered (AB and ABC-stacked) graphene and graphite. Finally, density functional theory simulations reveal that the presence of a charge- and current-induced electric field inside the graphene precursor facilitates phase transition by lowering the activation energy of the reaction. These results demonstrate that the passage of electrical current through a solid sample can directly drive nanocrystal nucleation in flash Joule heating, an insight that may inform future Joule heating or other electrical synthesis strategies.
https://www.science.org/doi/10.1126/sciadv.adh5131
Battery metal recycling by flash Joule heating
Abstract
The staggering accumulation of end-of-life lithium-ion batteries (LIBs) and the growing scarcity of battery metal sources have triggered an urgent call for an effective recycling strategy. However, it is challenging to reclaim these metals with both high efficiency and low environmental footprint. We use here a pulsed dc flash Joule heating (FJH) strategy that heats the black mass, the combined anode and cathode, to >2100 kelvin within seconds, leading to ~1000-fold increase in subsequent leaching kinetics. There are high recovery yields of all the battery metals, regardless of their chemistries, using even diluted acids like 0.01 M HCl, thereby lessening the secondary waste stream. The ultrafast high temperature achieves thermal decomposition of the passivated solid electrolyte interphase and valence state reduction of the hard-to-dissolve metal compounds while mitigating diffusional loss of volatile metals. Life cycle analysis versus present recycling methods shows that FJH significantly reduces the environmental footprint of spent LIB processing while turning it into an economically attractive process.
https://chemrxiv.org/engage/chemrxiv/article-details/66a25d215101a2ffa8053791
https://s3.eu-west-1.amazonaws.com/assets.prod.orp.cambridge.org
Kilogram Flash Joule Heating Synthesis with an Arc Welder
Lu Eddy , et al
[ PDF ]
Abstract -- Flash Joule heating has been used as a versatile solid-state synthesis method in the production of a wide range of products, including organic, inorganic, and ceramic products. Conventional flash Joule heating systems are large and customized, presenting significant barriers in the cost of assembly, the expertise needed to operate, and attaining uniformity of results between different systems. Even laboratory-scale flash Joule heating systems struggle to operate above 10-gram capacity, and they suffer poor temperature controllability. We present here the use of commercial off-the-shelf arc welders as a superior alternative to standard flash Joule heating systems due to their low cost ($120), ease of use, compact size, high temperature controllability, and tunability. We demonstrate gram-scale synthesis of a variety of organic and ceramic species using these systems. With the addition of a new reactor configuration for only $260, we scale up synthesis of these products to record rates for laboratory scale, achieving a production rate of 3 kg/h for graphene, and kg/day production rates for SiC, carbon nanotubes, SnSe2, and SnS¬2
https://www.nature.com/articles/s44359-024-00002-4
Nature Reviews Clean Technology volume 1, pages 32–54 (2025)
Flash Joule heating for synthesis, upcycling and remediation
Bing Deng et al
Abstract --Electric heating methods are being developed and used to electrify industrial applications and lower their carbon emissions. Direct Joule resistive heating is an energy-efficient electric heating technique that has been widely tested at the bench scale and could replace some energy-intensive and carbon-intensive processes. In this Review, we discuss the use of flash Joule heating (FJH) in processes that are traditionally energy-intensive or carbon-intensive. FJH uses pulse current discharge to rapidly heat materials directly to a desired temperature; it has high-temperature capabilities (>3,000 °C), fast heating and cooling rates (>102 °C s−1), short duration (milliseconds to seconds) and high energy efficiency (~100%). Carbon materials and metastable inorganic materials can be synthesized using FJH from virgin materials and waste feedstocks. FJH is also applied in resource recovery (such as from e-waste) and waste upcycling. An emerging application is in environmental remediation, where FJH can be used to rapidly degrade perfluoroalkyl and polyfluoroalkyl substances and to remove or immobilize heavy metals in soil and solid wastes. Life-cycle and technoeconomic analyses suggest that FJH can reduce energy consumption and carbon emissions and be cost-efficient compared with existing methods. Bringing FJH to industrially relevant scales requires further equipment and engineering development.
[ EXCERPTS ]
Key points:
Flash Joule heating (FJH) uses pulsed intense electric discharge to rapidly and directly heat materials for a short duration... Carbon materials, such as graphene, and inorganic materials can be synthesized using FJH and a variety of feedstocks... Waste can be managed and upcycled using FJH techniques, which are more energy efficient than conventional methods such as furnace-based heating... Remediation of soil contaminated with heavy metals and organic pollutants is feasible at laboratory scales with FJH... Life-cycle assessments suggest that compared with various other synthesis and waste management methods, FJH has reduced energy consumption and carbon emissions, especially when using waste feedstocks; FJH also appears to be cost-effective based on preliminary technoeconomic analyses... FJH is largely demonstrated at the bench scale, but scale-up of FJH is now being demonstrated on an industrial scale for materials production...
Following its introduction in 2020 for converting carbon sources into high-quality graphene11, FJH has been scaled, and its applications have expanded. FJH has been used in various materials synthesis and thermal treatment processes (Fig. 1A), including in bottom-up synthesis of graphene, carbon nanotubes, carbides, borides, nitrides, metallic glasses, transition-metal dichalcogenides and p-block metal chalcogenides, as well as doped and functionalized variants of these compounds. Waste materials can be used as feedstocks for materials synthesis, providing a substantial reduction in energy intensity and emissions for many FJH processes relative to using virgin materials FJH has also been applied in resource recovery and waste decontamination, including in perfluoroalkyl and polyfluoroalkyl substances (PFAS) destruction, soil remediation, waste plastic upcycling, and extraction of rare earth metals.
In this Review, we describe FJH, covering its fundamental principles, equipment design, applications, industrial implementation, sustainability and technoeconomic considerations. We begin by discussing the basic principles and theories underlying FJH, as well as the equipment and reactor designs. Subsequently, we highlight its potential applications in fields such as synthesis of carbon materials and metastable inorganic materials, resource recovery and waste upcycling, and environmental remediation. Sustainability and technoeconomic considerations are further discussed. Finally, we outline the remaining challenges that must be addressed to make FJH a mainstay of manufacturing and environmental stewardship.
Resistance heating
Resistance heating, also known as resistive heating or Joule heating, has its roots in the 1840s when James P. Joule discovered that heat could be generated by applying electricity to a resistor. Following Joule’s law, heat (Q) produced is proportional to the square of the current (I) multiplied by the electrical resistance (R) of the resistor and the heating time (t)...
Joule heating boasts a theoretical energy conversion efficiency (η) of 100%, meaning that all electric energy is converted into heat (see the table, which compares general resistive Joule heating with flash Joule heating (FJH)). This efficiency contrasts with the fuel utilization efficiency of furnaces, where chemical energy is transformed into heat through combustion. Furnace efficiency varies from 50% to 100% depending on the system design, but is often at the lower end of this range.
Resistive Joule heating is used in indirect heating resistance furnaces29, which are widely used across industry, such as in metallurg. In these furnaces, current passing through a material generates heat, which is then transferred to the medium through conduction, convection and/or radiation. Enclosures are typically used to isolate the heating process from the external environment. However, indirect resistance heating tends to have low energy efficiencies due to heat loss during the transfer process.
Unlike indirect Joule heating, direct Joule heating involves no intermediate heat transfer and therefore has very high energy efficiency. Direct heating for materials synthesis is used in the carbothermal shock process. This process involves the loading of metal feedstocks on a carbon substrate, followed by introduction of an electric pulse for rapid heating, resulting in nanoparticle synthesis. The feedstocks are in direct contact with the carbon paper, and heated by mainly conduction. The carbothermal shock method has been widely applied in the production of nanomaterials, ceramic processing, thermochemical synthesis and plastic depolymerization. FJH is another type of direct Joule heating and uses high temperatures and a fast duration (see the table). In addition to the direct contact heating, FJH can use the materials themselves as the resistive medium. In this e, heat transfer is not required, such that the efficiency can be even higher than the carbothermal shock process. Many other terms are used in the literature, such as high-temperature shock, high-temperature sintering, high-temperature electrothermal process, flash carbothermic reduction, flash upcycling, flash sintering and rapid Joule heating; some of these processes can have indirect characteristics or variations of carbothermal shock and FJH.
Fundamentals
Joule heating is a process by which an electrical current that passes through a resistive medium heats this medium by Joule’s law, according to which the heating power is equal to the electrical potential difference times the current flowing through the medium. Here, we define flash Joule heating as a direct heating process with a high-power, short-duration electrical pulse generated by a power source that is applied directly to a resistive material, causing extremely rapid heating of the target material to a wide temperature range, followed by rapid cooling. The target material can itself be the resistive material, or the target material can be in direct contact with the resistive material. The current density can exceed 10 A mm−2 and, when used in conjunction with a suitable electrically resistive material, leads to ultrahigh temperatures that can even exceed 3,500 °C (ref. 11). The current pulse width can be as short as milliseconds to seconds, resulting in ultrafast heating rates (typically 102 to 105 °C s−1; and ultrafast cooling rates (typically 102 to 104 °C s−1, owing to rapid thermal dissipation...
In contrast to furnace-based heating methods, FJH uses the materials themselves as the resistive medium, allowing for ~100% sample heating efficiency at heating rates up to 105 °C s−1. This fast heating rate and the subsequent fast cooling rate enable kinetically controlled non-equilibrium products to be formed. The high temperature of FJH (in excess of 3,500 °C) allows for rapid reaction to be completed on a millisecond to second timescale. Features including temperature range, heating and cooling rates, duration and heating manner distinguish FJH from conventional Joule heating.
FJH is an electrothermal process rather than a solely thermal process. Therefore, in addition to temperature increase, FJH features the passage of electric current through the reactants, which necessitates an electrical potential difference through the sample rather than just along a sample surface. The presence of an electric current passing through a material affects the chemical products13 and can lower reaction activation energies by as much as 50% (ref. 30). The passage of current through the material also promotes crystalline alignment of the flash-Joule-heated product along the axis of current flow, and this effect is further enhanced through rapid pulse-width modulation31. With the same current and voltage input, Joule heating performance depends on various materials properties, including thermal conductivity, a defined resistivity range and heat capacity, so the temperature is related to the materials.
Electric systems and hardware
FJH can be performed with any system that applies a sufficient voltage across the reactant medium. The methods were initially developed using capacitor-based systems... capacitor-based systems can achieve high power output, up to 1 MW, but are limited in output duration (usually subsecond timescales). Engineering techniques, such as pulse-width modulation by a variable frequency drive, can increase the capacitor discharge duration. Capacitor-based FJH systems can effectively be scaled up to kilogram production using rapid cycling of smaller batches, with automated sample loading and unloading to make the system continuous and high throughput. In these systems, the rate-determining step is often the repeated recharge time of the capacitor bank after each use.
Non-capacitor systems have the benefit of allowing continuous FJH without a necessary recharging step, offering higher energy delivery — despite reduced power output— owing to the long FJH timescales permitted. These non-capacitor, continuous systems exist in alternating-current (a.c.) and direct-current (d.c.) varieties. Alternating-current flash Joule heaters use a.c. electricity directly from the laboratory or manufacturing site, and they do not rectify the current before delivering it through the sample. Such systems are commonly used for pretreatment to reduce the electrical resistivity of a sample before subsequent d.c. flashing. Direct-current systems feature a device that rectifies the a.c. input from the facility to d.c. output to the sample and are the most common type of continuous flash Joule heater. These systems have programmable power supplies with which the desired voltage and current can be chosen before the reaction, and they can be programmed to adjust during FJH. In this way, continuous systems offer superior energy controllability and output relative to capacitor-based systems, while having inferior power output. Indeed, a capacitor-based FJH reaction can be completed in milliseconds, whereas an a.c.-based or d.c.-based FJH reaction can be sustained much longer.
Reactor design
Most FJH reactions involve filling the reactant feedstock into an FJH vessel, consisting of an insulative tube capped at the two ends by FJH electrodes made of either brass or graphite. Although other materials such as polytetrafluoroethylene are ocionally used35, the tube is typically fused quartz in laboratory settings, as its transparency allows for convenient observation and temperature measurement of the reaction through infrared and spectral methods. Fused quartz also has a high melting point (~1,650 °C), but this is rarely reached as minimal heat is transferred to the tube during the rapid FJH reaction. Additionally, the low thermal conductivity and low thermal expansion coefficient of fused quartz allow it to withstand cracking from thermal shock caused by rapid heating and cooling of FJH reactions. For large-scale applications, other refractory, cost-effective materials such as concretes, ceramics or brick might be used.
Before FJH, the feedstock is compressed between the electrodes to improve electrical contact and reduce the sample resistance. Vessels can either be sealed to contain the gaseous products of the flash reaction or instead have holes in the electrodes to allow pressure relief through reaction outgassing (Fig. 1Fc). Most FJH reaction vessels are deliberately not sealed to allow reaction outgassing and prevent high pressure buildup within the reaction vessel. This outgassing is often advantageous in removing volatile reactant impurities, resulting in higher product purity. Furthermore, outgassing prevents oxygen infiltration, protecting the reactants and products from burning at the high temperatures reached. The volatiles can also be collected for analysis of the reaction process. In some es, the volatiles are the desired products...
... the sample resistance should be in a suitable range for delivering the most electric energy. The real-time temperature profile during the FJH reaction is usually recorded using an infrared thermometer or a spectrometer when the temperature exceeds 3,000 °C...
Scale-up and industrial implementation
FJH is theoretically scalable. Experimentally, FJH has been conducted at various scales. In its early demonstration for flash graphene synthesis, which used a capacitor-based system with a total capacitance of 0.06 F and a maximum voltage of 200 V, the mass of product ranged from 0.03 g to 1 g per batch... Continuous FJH models have been introduced for flash graphene synthesis, including a continuous automatic device for flash graphene synthesis from biomass with a production rate of 21.6 g h−1...
Production of graphene and related carbon materials
FJH was originally developed for graphene production and is widely used in flash graphene synthesis. Related carbon materials are also synthesized via FJH, as the ultrahigh temperature makes it especially useful for carbon materials production: almost all carbon resources, including carbon black11, hard carbon, coal, cok, plastic, rubber, biomass46, food, CO2-derived amorphous carbon, pyrogenic carbon, and municipal solid waste, are graphitized below 3,000 °C...
Flash graphene production and characterizatio
...Turbostratic graphene can have an arbitrary number of layers that remain optically and electronically decoupled. Hence, it has electronic properties more similar to those of monolayer graphene than multilayer graphene, owing to that interlayer decoupling..
Flash graphene is characterized chiefly by Raman spectroscopy, which provides information on the crystallinity, defect density and turbostratic character.
The physical and spectroscopic characteristics of flash graphene vary with reaction parameters used in the FJH process, including power, energy and the feedstocks
Flash graphene has been demonstrated in various applications, especially those that require bulk amounts of graphene. For example, flash graphene is used as an additive in cement composites that increases compressive strength by ~25% with just 0.05 wt% flash graphene addition. It is also used in epoxy composites, concrete aggregate substitutes, lubricant additives68, lithium-ion batteries and conductive inks. In addition to the preparation of pristine graphene, FJH is also adopted for an in situ graphene coating on other materials to enhance their performances. For example, graphene-coated Cu particles show enhanced oxidation resistance, and graphene-coated lithium iron phosphate has improved rate performance in batteries...
Modified and functionalized flash graphene
FJH carbon feedstocks can produce modified graphene products and different carbon nanostructures. For instance, heteroatom-doped flash graphene (an effective material in battery electrodes and supercapacitors) is produced when a carbon feedstock is heated in the presence of a heteroatom-containing compound. The doped graphene exhibits increased defect densities and an increased interlayer spacing relative to non-doped graphene. Heteroatom doping ratios have been achieved above 10 at%.
When the feedstock is composed of a high proportion of non-carbon elements, such as boron or nitrogen, 2D turbostratic boron–carbon–nitrogen ternary compounds can be synthesized. When a sealed flashing vessel is used, and the carbon feedstock is mixed with a fluorinated polymer, new carbon morphologies can be formed, including fluorinated nanodiamond, fluorinated graphene and fluorinated concentric carbon35. These different structures have a time evolution in which the nanodiamonds form first at ~10 ms, and concentric carbon forms last at ~1 s. Using solid-state relays with millisecond-scale controllability, the reaction can be stopped in 1-ms increments along any point of the evolution. The heteroatom functionalization strategies of FJH can be extended to other materials such as 2D transition-metal carbides75, underscoring the versatility of FJH.
High-surface-area graphene is desirable for applications including electrocatalysis, battery anodes and sorption media. The flash graphene usually has a lower surface area than the feedstock, owing to thermal-induced aggregation of pores. Typically, feedstocks with high surface area, such as carbon black, form higher-surface-area flash graphene than do low-surface-area feedstocks such as coke. Porous carbon and flash graphene synthesized from bituminous coal exhibit effective adsorptive properties.
High-surface-area flash graphene can be produced from engineered high-surface-area precursors. For example, FJH of graphene oxide can produce highly defective and, thus, high-surface-area graphene, and ultrafine metal nanoparticles can be decorated on a reduced graphene oxide aerogel when metal precursors are preloaded on it. Similarly, when hollow mesoporous carbon spheres are used as feedstock, high-surface-area graphene hollow spheres can be produced with a surface area of up to 670 m2 g−1. Another strategy uses an etchant during FJH to increase the surface area. In the presence of Ca(OAc)2, FJH of plastics yields holey and wrinkled flash graphene with a surface area of up to 874 m2 g−1 and pore volume up to 0.32 cm3 g−1. In another e, KCl/K2CO3 salts have been used for the molten-salt synthesis of porous carbon from anthracite by FJH, achieving a surface area of 1,338 m2 g−1 and pore volume up to 9.95 cm3 g−1. As a comparison, activated carbon typically possesses a surface area of ~500–1,500 m2 g−1 and a pore volume of 0.3–0.8 cm3 g−1.
One-dimensional carbon nanostructure synthesis
One-dimensional carbon materials, including multiwalled carbon nanotubes (CNTs) and bamboo-like carbon fibres, are formed when a carbon feedstock is treated by FJH in the presence of a CNT growth catalyst, such as iron or nickel. The product formed from these reactions can be tuned by the FJH reaction temperature. A temperature of ~1,000 °C produces CNT without graphene; increasing temperature to ~2,000 °C leads to the formation of graphene–CNT hybrid structures; at temperatures beyond this, the ratio of CNT to flash graphene decreases such that virtually no CNTs remain by ~3,000 °C. Yield of CNT or hybrid morphologies, rather than 2D graphene morphologies, is estimated to be up to 90%, as observed by SEM imaging. Elemental purity of carbon can reach 98% even when waste plastics are used as feedstock. Commercial multiwalled CNTs could range from 90% to 99% in carbon purity.
Further, FJH treatment can convert some of the CNTs into graphene. The conversion proportion is affected by the reaction duration and temperature. These CNT–graphene composites are effective reinforcing additives in epoxy composites. Similarly, in the presence of a heteroatom-containing compound, heteroatom-doped CNT has been synthesized by FJH. When ammonia borane is used as the feedstock, boron nitride nanotubes can be produced. Other carbon forms with different graphitization degrees and morphologies can be produced by FJH, such as hard carbon and graphitic carbon cage.
Inorganic materials production
FJH is a versatile tool for phase engineering as it has a broadly tunable energy input capable of reaching temperatures >3,000 °C. FJH-synthesized materials with rationally engineered morphologies and electronic structures have unique properties that position them, for example, as promising high-performance catalysts in renewable energy devices. This section discusses the synthesis of inorganic materials, including metastable materials, solid-state materials and nanocatalysts.
Synthesis of metastable materials
Metastable materials can be produced through rapid heating or cooling during FJH, as the system does not have enough time to reach equilibrium. For instance, turbostratic flash graphene is a metastable phase as opposed to the more stable Bernal-stacked structures. FJH is emerging as a tool for engineering other metastability, as well, such as structural dislocation and defects.
The temperature tunability of FJH allows access to many metastable phases by making them thermodynamically preferable. A notable example is the phase conversion of transition-metal dichalcogenides, where bulk conversion of molybdenum dichalcogenides (MoS2) and tungsten dichalcogenides (WS2) from 2H phases to 1T phases was achieved in milliseconds, reaching a phase ratio of up to 76%. The 1T phases are metastable with higher free energy than the 2H phases. FJH induces structural changes in the 2H phase, particularly the formation of sulfide vacancies, which reverses the thermodynamic preference. A similar approach is used for the phase-controlled synthesis of transition-metal carbide nanocrystals. The ultrahigh-temperature capability of FJH enables the carbothermic reduction of metal oxides, leading to the synthesis of metal carbides within 1 s. By controlling pulse voltages, phase-pure molybdenum carbides, including stable β-Mo2C and metastable α-MoC1−x and η-MoC1−x, can be selectively synthesized. Carbon vacancies introduced during the FJH process are the structural factor for the phase transition of carbides.
Beyond vacancies, FJH can precisely tune the morphology and size of inorganic nanomaterials, providing another route for phase engineering, such as in the phase transformation synthesis of high-surface-area corundum nanoparticles. Aluminium oxide (Al2O3) has an unusual surface-area-dependent formation energy: α-Al2O3 is the thermodynamically stable phase of coarse crystals, whereas γ-Al2O3 has a lower surface area, causing nanocrystalline Al2O3 to usually crystallize in the γ-phase. The pulsed direct current input in the FJH process creates resistive hotspots at the interfaces between γ-Al2O3 nanoparticles, leading to controlled coarsening and an accompanying phase conversion from γ-phase to δ′-phase and then to α-phase.
The ultrafast cooling rate of the FJH process can kinetically retain the metastable phase at room temperature. This process is demonstrated by the kinetically controlled synthesis of metallic glass nanoparticles, as metallic glass can be obtained by rapid quenching. Metal precursors loaded on a carbon substrate are subjected to FJH, rapidly raising the temperature; the resulting alloy melts and cools at an ultrafast rate (104 °C s−1), vitrifying into glassy nanoparticles. Palladium-based and platinum-based metallic glass nanoparticles have been produced with this technique.
Rapid sintering and solid-state synthesis
Solid-state synthesis, also known as the ceramic method, is a reliable and versatile method for materials production and typically yields thermodynamically stable phases99. FJH is useful in solid-state synthesis owing to its ultrahigh-temperature capability and rapid heating rates, which secure the thermodynamic spontaneity of many reactions and enable fast diffusion and reaction kinetics. However, most feedstocks are not conductive enough for FJH, necessitating unique designs to deliver electricity and heat to the feedstock.
Graphite sheets are used as the heating element for ceramic sintering. Resistance heating is already widely used in flash sintering and spark plasma sintering101. Joule-heating-based sintering techniques can be faster, achieve higher temperatures and require less expensive apparatus. In a typical high-temperature sintering set-up, the pressed pellet of a ceramic precursor powder is sandwiched between two woven graphite sheets, which rapidly heat the pellet by conduction and radiation (Fig. 3c, bottom)38. The sintering can be completed in seconds, making it especially promising for solid-state electrolytes to prevent loss of volatile elements such as lithium38,102. Rapid Joule-heating-based sintering has also been used to construct interfaces between solid electrolytes and cathodes, overcoming large interfacial resistances103. In addition, Joule-heating-based sintering has been previously explored in structural ceramic sintering, such as alumina ceramics from corundum nanoparticles39; however, the densification is relatively poor because of the limited sintering time. Joule-heating-based sintering would be useful for sintering ceramics that have volatile element components but less stringent requirements for densification.
Flash-within-flash (FWF) Joule heating has also been developed for inorganic synthesis... The FWF process involves two quartz vessels: an outer vessel filled with conductive additives and an inner vessel loaded with feedstocks for the solid-state synthesis (Fig. 3d, left). The current applied to the outer vessel generates intense heat, which is then transferred through an inner vessel to the inner feedstock by conduction and radiation to drive chemical reactions. Thus, FWF is an indirect heating method. The FWF can be used multiple times or in an anion-exchange mode. FWF is a versatile, efficient and scalable method for the production of phase-selective, single-crystal bulk powder materials at the gram scale, as demonstrated by the synthesis of ten transition-metal dichalcogenides, three group XIV dichalcogenides and nine non-transition-metal dichalcogenide materials. In the FWF configuration, metal precursors are not in contact with the carbon in the outer tube, so metal carbide formation is mitigated. These two designs — woven graphite sheet heating elements and outer–inner tube FWF configurations — enable the use of non-conductive materials, or even materials that are too conductive, greatly expanding the versatility of the FJH process. These methods rely primarily on thermal conductive heating, but rapid heating rates and efficiencies differentiate them from traditional furnace heating methods.
Carbon-supported inorganic nanocatalysts
Inorganic nanomaterials can be synthesized by FJH, typically using carbon materials such as carbon black and carbon nanofibre as conductive additives and substrates, as their electrical resistance makes them suitable for Joule heating. After loading precursors onto the carbon support, the current passing through the carbon instantly generates heat. The heat leads to the decomposition, reaction and fusion of the precursors, and then solidification to form nanoparticles during the cooling stage...
The precise control of reaction time down to milliseconds during FH allows for the formation of dispersed, ultra-small particles by preventing their agglomeration. The carbon supports are vital for the dispersion and stability of nanoparticles by providing numerous nucleation and binding sites. Moreover, as FJH is a dry process, the surface of the as-produced nanomaterials remains clean, in contrast to materials synthesized by wet chemistry, which are often contaminated by surfactants and capping agents18. Their cleanliness and structure make the FJH-produced materials suitable for use as catalysts in a variety of applications, including thermal catalysis114,115, electrocatalysis95,107,111,118,125, environmental catalysis108 and photocatalysis126,127.
FJH is primarily used for solid-state synthesis, but with proper reactor design it can be integrated into wet chemistry and gas reactions. A wet-interfacial Joule heating approach has been proposed to synthesize various nanomaterials from solution feedstocks. By instantaneous evaporation of solvents that are on the carbon heater, synthesis is completed in <1 s. For thermochemical synthesis, a non-equilibrium synthesis that uses programmable electric current to rapidly heat and quench gas reactions has been demonstrated130, achieving methane pyrolysis with high selectivity to C2 products.
Resource recovery and waste upcycling
Thermal treatment is commonly used in resource recovery and waste upcycling131. However, increased energy efficiency and reduced costs and emissions are needed to ensure that the value of the recovered products can offset the process costs. FJH is therefore being explored for the recovery of metals from waste streams such as electronic waste (e-waste), industrial wastes and spent batteries22,27,36,132,133, the upcycling of inorganic wastes22,134, and the conversion of carbonaceous waste (such as plastics and rubbers) into graphitic materials.
Metal recovery and inorganic waste upcycling
Metals are often the most valuable and recoverable components of waste. Their recovery involves altering their chemical forms, speciation, and distribution to enable their separation from wastes based on property differences. FJH, with its high-temperature capability and cost-effectiveness, makes these conversions feasible and economic.
Critical metals recovery from e-waste and industrial wastes
FJH in metal recovery was originally demonstrated in urban mining, through the gram-scale recycling of precious metals from e-wastes — specifically, waste printed circuit boards36. The difference between the vapour pressures of metals and those of the substrate materials (carbon, ceramics and glass) allows the separation of metals, which is called evaporative separation. Precious metals in e-wastes are heated and evaporated by ultrahigh-temperature FJH; then the metal vapours are transported and condensed in a cold trap (Fig. 4a). With the assistance of chlorination (converting the metal into its chloride by reacting with chlorinating agents), recovery yields of >80% were achieved for rhodium, palladium, silver and gold within 1 second.
Integration of FJH into an electrothermal chlorination or electrothermal carbochlorination process is performed for selective separation of critical metals from waste feedstocks136. The electrothermal chlorination process leverages the differences in the free energy of formation of metal chlorides as well as the kinetic selectivity due to the ultrafast heating and cooling capability of FJH. This process has been demonstrated in the recovery of gallium, indium and tantalum from e-wastes with purities >95% and yields >88%.
FJH has also been used to recover rare earth metals from coal fly ash, a by-product of coal combustion. In this process, FJH thermally converts the hard-to-dissolve rare earth phosphates into rare earth oxides and metals with high solubility (Fig. 4b). The FJH activation increased the recovery yield of rare earth metals roughly twofold compared with directly acid leaching the raw materials. This method is also applicable to other wastes like e-wastes and bauxite residues (red mud)27.
Recycling and regeneration of spent batteries
Battery cathodes can be recycled through hydrometallurgy, which typically involves acid leaching of metals. However, the transition metals in active cathode materials with high valence states lead to low leaching efficiency. FJH has been applied to make this process more efficient by heating the black mass, which is the combined anode and cathode waste routinely used in the recycling industry. This process led to the thermal decomposition of the compact solid–electrolyte interphase (SEI) and the carbothermic reduction of the spent cathode materials (LiNixMnyCo1−x−yO2, LiCoO2, LiNixCoyAl1−x−yO2 and LiFePO4) into their lower oxidation state or metallic form. With this FJH activation, the metal recovery yield was improved from <35% to >98%.
Direct recycling (regeneration of battery materials without destroying their crystal structures) has gained attention due to potential reduced environmental impacts and economic costs relative to destructive recycling such as hydrometallurgy. High-temperature calcination that gasifies organics for graphite anode regeneration is technically straightforward, but as graphite is less valuable than cathode materials, furnace-based extended calcination is often not economically viable. FJH has been applied to decompose the impurities and regenerate the entire graphite anode in 1 second, which significantly reduces the energy consumption and carbon emission compared with high-temperature calcination recycling. The recycled anode preserves the graphite structure while being coated with an SEI-derived carbon shell, contributing to high battery performance.
Another FJH-based process involves converting the loose SEI layer that is coated onto the degraded graphite into a compact and mostly inorganic mass that encloses active lithium, leading to >100% initial Coulombic efficiency, superior to commercial graphite. A similar strategy was applied to regenerate spent cathode carbon blocks of aluminium electrolytic cell. In addition to anode regeneration, FJH can achieve the direct recycling of cathodes, such as the relithiation of LiCoO2 and repair of its crystal structure. FJH was also combined with magnetic separation and solid-state relithiation to restore fresh cathodes from waste cathodes, with battery metal recovery yields of ~98%.
Upcycling inorganic wastes into value-added materials
Recycling inorganic wastes that are less valuable than critical metals, such as glass and silicon, is often less profitable. As a result, these waste streams are usually directly landfilled instead of recycled. However, similar to its application in the synthesis of inorganic materials, FJH can be used to convert inorganic waste to value-added inorganic materials. As low-value materials often constitute a major part of inorganic wastes, their upcycling by FJH represents a promising path toward their secondary utilization.
For example, FJH has been used to upcycle glass-fibre-reinforced plastics into silicon carbide22, a high-performance reinforcement and semiconducting material. Waste glass-fibre-reinforced plastics were mixed with waste carbon-fibre-reinforced plastics as conductive additives. FJH rapidly converted the glass fibre to SiC by carbothermic reduction. The phase of SiC can be controlled by the FJH process, similar to the phase-controlled synthesis of molybdenum carbides15. The SiC powder obtained was further used as an anode for lithium-ion batteries22. In another example, the rapid Joule heating process converts photovoltaic silicon waste into silicon nanowire electrodes for lithium-ion batteries.
Carbonaceous waste upcycling
FJH production of graphene was initially optimized with amorphous carbon and coal, but many other low-value carbonaceous waste streams have been upcycled into graphene via FJH. Upcycling carbonaceous waste into high-value products such as graphene can economically incentivize the responsible disposal and recovery of resources145. The value of the product required to offset process costs is dependent on the demonstrated application, and several promising pathways are discussed here.
Upcycling of waste plastics and rubbers into flash graphene
FJH can be used to upcycle waste plastics and other petrochemical wastes, such as rubber, pyrolysis ash and asphaltenes. For example, mixed plastic wastes have been converted to graphene via FJH in a process that does not require sorting or washing (which involves high process costs). Graphene derived from waste plastics has been tested in applications of lubricant, automotive composite applications, 3D printing and corrosion resistance, and electromagnetic field absorption. Graphene derived from coal has been used as a total substitute for concrete aggregates, producing concrete that is 25% lighter and has superior mechanical properties.
Because of the resistive heating nature of FJH, samples must be conductive enough to support the rapid discharge of current required to achieve high temperatures during the process. As waste plastics are not conductive enough, conductive additives are needed. Typically, 10–20 wt% of conductive additives, such as carbon black, tyre-carbon black, charcoal or coal, can be added to reduce the resistance to <10 Ω; however, this can be a costly additive when processing waste streams. A two-step FJH strategy has been developed to use as little as 2–3 wt% of carbon black in the conversion of ground waste plastics into graphene. In this two-step method, a longer-duration (10-s), lower-current discharge is conducted to carbonize the carbonaceous feedstock, increasing the conductivity of the material and resulting in volatile outgassing. After this low-current FJH, where some volatile mass is lost dependent on feedstock, the sample resistance is <10 Ω, allowing high-current FJH to occur, as shown in the graph of current versus time in Fig. 5a. Raman spectroscopy shows defective graphitic structure after low-current FJH, which is then annealed into high-quality turbostratic graphene after high-current FJH. The carbon black additives are simultaneously converted to graphene, so their separation is not required.
The longer heating duration of the two-step FJH process allows alternative products to be synthesized. For example, the incorporation of <1 wt% salts such as FeCl3 catalysed the formation of 1D carbon nanotubes and nanofibres with controllable diameters. By parameter tuning, hybrid morphologies of graphene domains embedded with 1D nanofibres were also produced, which resulted in superior composite mechanical properties when tested in epoxy composites. The incorporation of calcium salts can also function as blowing agents and proppants to increase and maintain the specific surface area during the FJH process. Through the evolution of gases, porosity and wrinkles can be included in the material, resulting in holey, wrinkled flash graphene.
Upcycling of waste plastics into hydrogen and chemicals
Carbonization occurs during the low-current FJH of plastics, forming hydrocarbon volatiles including substantial proportions of H2 gas. High yields of H2 were observed regardless of plastic type , with lower initial sample resistances resulting in more complete hydrocarbon breakdown to form higher yields of H2 and flash graphene. Hydrogen efficiencies as high as 93% were observed, and no CO2 is produced during the FJH of polyolefins. Compared with traditional pyrolysis26, the higher heating rate of FJH results in a substantially different product distribution (90 vol% H2). FJH is, therefore, a catalyst-free method to produce clean H2 from mixed waste plastics, with the costs potentially offset by the co-production of high-value graphene.
Depolymerization is another widely adopted strategy for waste plastic upcycling. An electrified spatiotemporal heating process based on the rapid Joule heating technique has been tested in the pyrolysis of commodity plastics. This catalyst-free, far-from-equilibrium thermochemical depolymerization method promotes depolymerization while suppressing unwanted side reactions, leading to high-yield monomer recovery: 36% for polypropylene and 43% for poly(ethylene terephthalate). H-ZSM-5 was later introduced as a catalyst to efficiently deconstruct polyolefin plastic wastes into light olefins C2–C4. In that demonstration, the pulsed current input was critical for producing a narrow distribution of gaseous products.
Upcycling of biomass into flash graphene
Although thermal conversion of biomass to biochar has been widely adopted151, the conversion of biomass to high-value carbon materials such as graphene represents a value-added upcycling route. Biomass such as sawdust and straw152, lignin147, waste food11, hair46 and even mixed municipal waste49 can be upcycled into graphene by FJH. No catalyst is required. However, biomass is not conductive, so a conductive additive such as carbon black is required. The biomass usually contains a high oxygen content, such that massive pyrolytic volatiles are released during the FJH process, which accounts for 60–70% of carbon emissions152. A two-step process has
been developed to allocate energy efficiently37 and address these emissions. Initially, pyrolysis is used to release biomass pyrolytic volatiles; subsequent FJH reaction is carried out to optimize the flash graphene structure (Fig. 5e). An integrated automatic FJH system has also been built (Fig. 5f), enabling the continuous production of biomass-derived graphene at the productivity of 21.6 g h−1 (ref. 37).
Environmental remediation
Environmental remediation processes, such as thermal treatment, thermal desorption and high-temperature vitrification, can have high energy usage and by-products. Improving energy efficiency, reducing by-product emissions and using renewable energy are key research areas toward sustainability in environmental remediation153. Owing to its versatility, energy efficiency, widely tunable temperature range (up to 3,000 °C) and lack of secondary waste, FJH has been applied in environmental remediation, including as a thermal process for the decontamination of hazardous wastes and remediation of soil, and in material synthesis for pollution degradation, as discussed in the following sections.
Decontamination of hazardous wastes
Thermal treatment is widely used in hazardous waste decontamination and environmental remediation153,154. FJH can achieve a wide temperature range, which is sufficient to degrade organic pollutants and remove heavy metals by evaporation. Heavy metals (including Cd, As, Pb, Ni and Co) have high vapour pressure (Fig. 6a), enabling their evaporative removal with efficiencies of 70–90% at temperatures just below 3,000 °C. For example, during the urban mining of precious metals by FJH, toxic heavy metals, such as Hg, As, Cd, Pb and Cr, are removed by evaporation and then captured by condensation36. The heavy metal content in the residual waste is reduced to within safe limits after two to three FJH pulses under 120 V FJH. Heavy metals in coal fly ash155 have also been removed during treatment with FJH (Fig. 6a), allowing the purified coal fly ash to be used as a low-carbon cementitious material with reduced heavy metal leaching155. FJH has also been used to recycle
Flash Joule heating (FJH) can be used in waste decontamination and soil remediation instead of or in addition to conventional processes. a, The removal of heavy metals from coal fly ash (CFA, left), vapour pressure of different heavy metals (centre) and their removal efficiencies by FJH (right). b, FJH process for degradation of perfluoroalkyl and polyfluoroalkyl substances (PFAS), in which PFAS adsorbed on granular activated carbon (GAC) is mixed with a metal hydroxide (NaOH or Ca(OH)2). FJH converts the PFAS into non-toxic NaF or CaF2. c, The high-temperature electrothermal process enabled by FJH for soil remediation. The soil is premixed in place, with biochar or other conductive carbon to provide sufficient conductivity. The electrodes provide a rapid voltage pulse for Joule heating, carbonizing the organic pollutants and reducing and vaporizing heavy metals, which are removed by the vacuum piping system. d, Electrothermal mineralization for bulk soil remediation of PFAS contaminants. REM is rapid electrothermal mineralization, an FJH process within soil. CB, carbon black.
FJH has been shown to be an effective technique for the electrothermal mineralization of PFAS157. A common strategy to remove PFAS in water is adsorption, using sorbent-like granular activated carbon..
Soil remediation
Thermal desorption, such as in thermal conduction heating and electrical resistive heating, is a practical method for soil remediation... FJH can be applied to soil remediation to remove multiple pollutants simultaneously: heavy metals are removed by evaporation, while persistent organic pollutants such as polycyclic aromatic hydrocarbons are removed by carburization.
Compared with conventional thermal techniques, the electrothermal remediation processes are much faster, within seconds rather than days or even months, and they have higher degradation capability for pollutants25. For example, the removal efficiencies of tested heavy metals such as Cd, Hg and Pb were >80% in a single FJH pulse..
FJH has also been used for the remediation of PFAS in soil at the kilogram scale24 (Fig. 6d). With biochar as a conductive additive, FJH is used to ramp the soil temperature to >1,000 °C in seconds. PFAS then reacts with in situ calcium compounds to form calcium fluorides and other alkaline earth fluorides, which are non-toxic and the natural mineralized form of fluoride in the environment. High PFAS removal efficiencies of >99% have been achieved with this method without the use of any external reagents...
Functional materials for pollutant degradation and removal
Environmental catalysis for pollutant degradation can be synthesized via FJH without producing secondary waste during their synthesis. For example, iron-based material is one of the most important catalysts for the advanced oxidation process to degrade organic pollutants in wastewater161...
In addition to acting as catalysts for oxidation processes, low-valent or zero-valent metals are promising for reductive remediation163. During FJH synthesis, a carbon layer is coated on the Fe(0) nanoparticle, which prevents its surface oxidation164. This Fe–C composite demonstrates superior reductive remediation of multiple pollutants in wastewater, such as water-soluble PFAS, Cr(VI) and Sb(V)...
FJH can also produce the materials for the removal of volatile organic compounds, such as carbon-supported Ag–Co3O4 bimetallic catalyst for the catalytic oxidation removal of formaldehyde166. In another example, Joule heating serves as the thermal source to drive the catalytic oxidation of volatile organic compounds using Pt/CeO2 as the catalysts. This Joule-heating-based catalytic system exhibits an ultralow input power167, 87% lower than that of a conventional heating furnace.
Sustainability and technoeconomic considerations...
Graphene and inorganic materials production
LCA typically includes raw material and resource extraction, which can have high environmental burdens. These impacts can be minimized or even eliminated when using waste feedstocks for flash graphene and other material synthesis by FJH (Fig. 7a), as it requires no graphite mining or solvents in processing. Using waste materials, such as pyrolysis ash146, waste plastics12,14, waste printed circuit boards36, e-wastes136, retired wind turbine blades22, coal fly ash155 and spent rechargeable batteries132, as feedstocks has provided a substantial reduction in energy intensity and emissions for many FJH processes...
... FJH synthesis of other graphitic nanomaterials, such as carbon nanotubes and nanofibres, also has an 86–94% reduction in emissions and energy demand versus conventional production methods14. Similar results were observed for transition-metal dichalcogenide production compared with current production methods20.
In solid-state syntheses, FJH competes primarily with chemical exfoliation168, chemical vapour deposition 169,170, and electrochemical intercalation171 ... FJH has short reaction times and can use low-cost or waste feedstocks with minimal waste by-products, so there can be a substantial decrease in the production cost of flash graphene and related products..
Waste upcycling and decontamination
The application of FJH for metal recovery, waste decontamination and environmental remediation has advantages relative to various widely used methods, based on LCA and TEA. For example, the recycling of battery cathode metals by FJH has reduced water consumption, energy usage, greenhouse gas emissions and costs compared to virgin mining, hydrometallurgical processing, and pyrometallurgical processing132 (Fig. 7f-h). Similarly, compared to synthetic graphite production and high-temperature calcination recycling133, the flash recycling of graphite anode materials had substantial reductions in water and energy consumption and greenhouse gas emissions. These reductions were attributed to the rate and energy efficiency of the FJH process. The environmental impacts and costs of upcycling plastic-reinforced glass fibre by FJH have also been compared with other approaches22. The operating cost of FJH was equivalent to ~0.2% and ~3.4% of the solvolysis and incineration processes, respectively, to recycle the same amount of waste plastic-reinforced glass fibre and produce the same amount of silicon carbides.
FJH seems to be economically feasible and a viable approach to waste decontamination and environmental remediation. In an LCA of heavy metal removal from coal fly ash by FJH and its reuse in cement155, there was a 30% reduction in greenhouse gas emissions compared with direct landfilling of the coal fly ash. These results indicate that the coal fly ash can be used as a lower-carbon-footprint cement. A TEA of FJH in soil remediation demonstrated that the electrothermal remediation process shows a 5–70% reduction in operating expenses relative to the different established methods, such as thermal desorption, soil washing and chemical oxidation, that are used at the industrial scale25. Similar analyses have been conducted on electrothermal PFAS mineralization by FJH24,157, showing its substantial reduction in energy consumption, greenhouse gas emissions, water consumption and operation costs when compared with existing methods such as incineration, ball milling and chemical oxidation.
Limitations of current LCA and TEA
As with all preliminary LCA and TEA, the current analyses of the FJH process have limitations. These include assumptions or omissions regarding scalability, transportation, waste feedstock availability and cost, as well as disposal of waste by-products. Widespread adaptation of sustainable technologies based solely on top-line, preliminary LCA and TEA data might result in over-estimation of environmental benefits or efficiency improvements, owing to altered consumption behaviours172,173. This rebound effect in the circular economy is a result of projected efficiency gains of new sustainable technology being unrealized, owing to increased consumption of goods once the technology has reached large scales174.
As many of the published L conducted on the FJH processes are preliminary in scope and make assumptions about scale and adoption, most do not consider rebound effects. For example, a lower cost of graphene would logically result in increased consumption, which could result in an overall increase in burdens and footprint attributable to the graphene market, even with the improved efficiency of the FJH process. This would be a direct rebound effect, but indirect rebound effects could also be observed in which the increased efficiency and lowered cost might result in an increased prevalence of unrelated manufacturing processes, such as increased cathode production due to the implementation of cheaper anode recycling. Both direct and indirect rebound effects can be difficult to predict, and they also apply to TEA, not only to LCA projections175. Further examples of rebound effects include the increased demand for biomass-derived FJH graphene, resulting in higher overall biomass consumption and thus greater land use burdens or increased emissions from transportation.
Scientists can help to acknowledge these possibilities by conducting thorough uncertainty analysis in LCA and TEA, as well as considering a wide array of scenarios, including process energy sources, materials transportation, and comparison to associated primary production routes that might have increased use rather than a decline in use176. Furthermore, detailed LCA and TEA with a broader scope, using different assumptions, comparing different methods or analysing different scale FJH processes, can enhance the quantified understanding of cost and burden efficiency. Overall, conducting LCA and TEA during the early stages of FJH developments, optimization and scale-up can help to identify steps of high burden, as well as benchmark or suggest the sustainability in quantifiable terms.
Summary and future perspectives
FJH has emerged as an efficient electrification technology for materials production, metal recycling, waste upcycling and environmental remediation. Its hallmark features, including high energy efficiency, short reaction duration, solvent-free processing, minimal heat loss, versatile operation models and compact reactor design, provide advantages over traditional combustion-based heating or wet-chemistry methods. Despite progress in the development and application of FJH, efforts are needed to elucidate the underlying mechanisms, better harness its characteristics and advance FJH toward industrial-scale implementation.
More experimental and theoretical analyses are needed to uncover the mechanism and improve the controllability of FJH. Advanced characterization under realistic in operando reaction conditions will be necessary to clarify the reaction and conversion details177. FJH is a multi-physical phenomenon that combines electric fields, thermal fields, and intense light emission. A comprehensive understanding of the multifield coupling effect is crucial for enhancing its controllability. Further, improving temperature control is necessary for better uniformity of the reaction conversions.
FJH complements existing heating techniques, such as furnace heating, microwave heating and induction heating. Its differences from these techniques offer new possibilities for researchers working in diverse disciplines applications, as demonstrated by the successful application of FJH in materials production, chemical syntheses and environmental remediation. In particular, few applications in wet chemistry and gas reactions have been reported, but these warrant further investigation as the ultrafast and highly localized heating of FJH could offer distinct kinetic and thermodynamic advantages over traditional heating methods. FJH for waste recycling and environmental remediation also requires more detailed comparative studies than established methods before deployment.
The scale-up of the FJH process and its industry-scale implementation and automation are pivotal to realizing its use in energy-efficient applications. The prototype productivity of flash graphene production had been reported at larger scales, but the FJH synthesis of inorganic materials is at the gram-scale level in the laboratory. Ideally, lessons on scalable FJH technology in graphene production can be adapted for the mass production of other materials. Scale-up is also needed for waste recycling and environmental remediation, given the quantities of solid waste generated. For instance, coal power plants currently produce >750 million tonnes of fly ash per year178. For further scale-up, the electricity supply system needs design upgrades to ensure high and rapid power input41. For pilot-scale or industrial implementation of FJH, waste heat recovery and off-gas treatment systems should be integrated into FJH systems, allowing heat and gas to be recovered from the FJH process. This design requires collaboration between academia and industry to bring FJH into large-scale practice.
References
Luong, D. X. et al. Gram-scale bottom-up flash graphene synthesis. Nature 577, 647–651 (2020).
Wyss, K. M. et al. Upcycling end-of-life vehicle waste plastic into flash graphene. Commun. Eng. 1, 3 (2022).
Huang, P., Zhu, R., Zhang, X. & Zhang, W. Effect of free radicals and electric field on preparation of coal pitch-derived graphene using flash Joule heating. Chem. Eng. J. 450, 137999 (2022).
Deng, B. et al. Phase controlled synthesis of transition metal carbide nanocrystals by ultrafast flash Joule heating. Nat. Commun. 13, 262 (2022).
Okulov, I. V. et al. Flash Joule heating for ductilization of metallic glasses. Nat. Commun. 6, 7932 (2015).
Choi, C. H. et al. Flash-within-flash synthesis of gram-scale solid-state materials. Nat. Chem. 16, 1831–1837 (2024).
Chen, W. et al. Heteroatom-doped flash graphene. ACS Nano 16, 6646–6656 (2022).
Cheng, Y. et al. Flash upcycling of waste glass fibre-reinforced plastics to silicon carbide. Nat. Sustain. 7, 452–462 (2024).
Eddy, L. J. et al. Automated laboratory kilogram-scale graphene production from coal. Small Methods 8, 2301144 (2024).
Cheng, Y. et al. Electrothermal mineralization of per- and polyfluoroalkyl substances for soil remediation. Nat. Commun. 15, 6117 (2024).
Deng, B. et al. High-temperature electrothermal remediation of multi-pollutants in soil. Nat. Commun. 14, 6371 (2023).
Wyss, K. M. et al. Synthesis of clean hydrogen gas from waste plastic at zero net cost. Adv. Mater. 35, 2306763 (2023).
Deng, B. et al. Rare earth elements from waste. Sci. Adv. 8, eabm3132 (2022).
Joule, J. P. On the production of heat by voltaic electricity. Proc. R. Soc. Lond. 4, 280–281 (1841).
Eddy, L. et al. Electric field effects in flash Joule heating synthesis. J. Am. Chem. Soc. 146, 16010–16019 (2024).
Cheng, Y. et al. Electric current aligning component units during graphene fiber Joule heating. Adv. Funct. Mater. 32, 2103493 (2022).
Zhang, X. H., Han, G. Y. & Zhu, S. Flash nitrogen-doped carbon nanotubes for energy storage and conversion. Small 20, 2305406 (2024).
Algozeeb, W. A. et al. Flash graphene from plastic waste. ACS Nano 14, 15595–15604 (2020).
Saadi, M. A. S. R. et al. Sustainable valorization of asphaltenes via flash Joule heating. Sci. Adv. 8, eadd3555 (2022).
Chen, W. et al. Ultrafast and controllable phase evolution by flash Joule heating. ACS Nano 15, 11158–11167 (2021).
Deng, B. et al. Urban mining by flash Joule heating. Nat. Commun. 12, 5794 (2021).
Zhu, X. et al. Continuous and low-carbon production of biomass flash graphene. Nat. Commun. 15, 3218 (2024).
Wang, C. et al. A general method to synthesize and sinter bulk ceramics in seconds. Science 368, 521–526 (2020).
Mishra, S. & Ullas, A. V. Concept modelling of small scale device for continuous production of graphene using Solidworks. Mater. Today Proc. 79, 345–348 (2023).
Eddy, L. et al. Kilogram flash Joule heating synthesis with an arc welder. Preprint at ChemRxiv https://doi.org/10.26434/chemrxiv-2024-nfnc9 (2024).
Dong, S. et al. Rapid carbonization of anthracite coal via flash Joule heating for sodium ion storage. ACS Appl. Energy Mater. https://doi.org/10.1021/acsaem.3c02975 (2024)
Liu, X. & Luo, H. Preparation of coal-based graphene by flash Joule heating. ACS Omega 9, 2657–2663 (2024).
Advincula, P. A. et al. Flash graphene from rubber waste. Carbon 178, 649–656 (2021).
Teng, T. et al. Flash reforming pyrogenic carbon to graphene for boosting advanced oxidation reaction. Adv. Mater. Technol. 8, 2300236 (2023).
Cheng, L. et al. Flash healing of laser-induced graphene. Nat. Commun. 15, 2925 (2024).
Kokmat, P., Surinlert, P. & Ruammaitree, A. Growth of high-purity and high-quality turbostratic graphene with different interlayer spacings. ACS Omega 8, 4010–4018 (2023).
Garlow, J. A. et al. Large-area growth of turbostratic graphene on Ni(111) via physical vapor deposition. Sci. Rep. 6, 19804 (2016).
Beckham, J. L. et al. Machine learning guided synthesis of flash graphene. Adv. Mater. 34, 2106506 (2022).
Wyss, K. M., Wang, Z., Alemany, L. B., Kittrell, C. & Tour, J. M. Bulk production of any ratio 12C:13C turbostratic flash graphene and its unusual spectroscopic characteristics. ACS Nano 15, 10542–10552 (2021).
Stanford, M. G. et al. Flash graphene morphologies. ACS Nano 14, 13691–13699 (2020).
Deng, B. et al. Growth of ultraflat graphene with greatly enhanced mechanical properties. Nano Lett. 20, 6798–6806 (2020).
Advincula, P. A. et al. Waste plastic- and coke-derived flash graphene as lubricant additives. Carbon 203, 876–885 (2023).
Zhou, C. et al. Preparation of graphene-coated Cu particles with oxidation resistance by flash joule heating. Carbon 224, 119060 (2024).
Zhu, S. et al. Flash nitrogen-doped graphene for high-rate supercapacitors. ACS Mater. Lett. 4, 1863–1871 (2022).
Chen, W. et al. Turbostratic boron–carbon–nitrogen and boron nitride by flash Joule heating. Adv. Mater. 34, 2202666 (2022).
Wyss, K. M., Chen, W., Beckham, J. L., Savas, P. E. & Tour, J. M. Holey and wrinkled flash graphene from mixed plastic waste. ACS Nano 16, 7804–7815 (2022).
Liao, Y. T. et al. Ultrafast synthesis of 3D porous flash graphene and its adsorption properties. Colloid Surf. A 676, 132178 (2023).
Li, Q. et al. Rapid preparation of porous carbon by flash Joule heating from bituminous coal and its adsorption mechanism of methylene blue. Colloid Surf. A 682, 132900 (2024).
Dong, S. et al. Flash Joule heating induced highly defective graphene towards ultrahigh lithium ion storage. Chem. Eng. J. 481, 147988 (2024).
Xia, D. et al. Electrothermal transformations within graphene-based aerogels through high-temperature flash Joule heating. J. Am. Chem. Soc. 146, 159–169 (2024).
Huang, J., Zhu, S., Zhang, J. & Han, G. One-pot ultrafast molten-salt synthesis of anthracite-based porous carbon for high-performance capacitive energy storage. ACS Mater. Lett. 6, 2144–2152 (2024).
Advincula, P. A. et al. Tunable hybridized morphologies obtained through flash Joule heating of carbon nanotubes. ACS Nano 17, 2506–2516 (2023).
Chen, J. et al. Boron nitride nanotube and nanosheet synthesis by flash Joule heating. Preprint at ChemRxiv https://doi.org/10.26434/chemrxiv-2024-mvrmf (2024).
Yuan, M., Yu, S., Wang, K., Mi, C. & Shen, L. Ultrafast synthesis of hard carbon for high-rate and low-temperature sodium-ion storage through flash Joule heating. Solid. State Ion. 414, 116622 (2024)
Song, Z. et al. Joule heating for structure reconstruction of hard carbon with superior sodium ion storage performance. Chem. Eng. J. 496, 154103 (2024).
Wang, L. et al. Rapid and up-scalable flash fabrication of graphitic carbon nanocages for robust potassium storage. Adv. Funct. Mater. 34, 2401548 (2024).
Chen, W. et al. Millisecond conversion of metastable 2D materials by flash Joule heating. ACS Nano 15, 1282–1290 (2021).
Liu, S. et al. Extreme environmental thermal shock induced dislocation-rich Pt nanoparticles boosting hydrogen evolution reaction. Adv. Mater. 34, 2106973 (2022).
Klement, W., Willens, R. H. & Duwez, P. O. L. Non-crystalline structure in solidified gold–silicon alloys. Nature 187, 869–870 (1960).
Grover, V., Mandal, B. P. & Tyagi, A. K. in Handbook on Synthesis Strategies for Advanced Materials Vol. I Techniques and Fundamentals (eds Tyagi, A. K. & Ningthoujam, R. S.) 1–49 (Springer Singapore, 2021).
Yu, M., Grasso, S., McKinnon, R., Saunders, T. & Reece, M. J. Review of flash sintering: materials, mechanisms and modelling. Adv. Appl. Ceram. 116, 24–60 (2017).
Shin, J. et al. In2Se3 synthesized by the FWF method for neuromorphic computing Adv. Electron. Mater. https://doi.org/10.1002/aelm.202400603 (2024).
Yao, Y. et al. Carbothermal shock synthesis of high-entropy-alloy nanoparticles. Science 359, 1489–1494 (2018).
Chen, Y. et al. Ultra-fast self-assembly and stabilization of reactive nanoparticles in reduced graphene oxide films. Nat. Commun. 7, 12332 (2016).
Wang, M. et al. In situ generation of flash graphene supported spherical bismuth nanoparticles in less than 200 ms for highly selective carbon dioxide electroreduction. ACS Mater. Lett. 6, 100–108 (2024).
Yu, F. et al. Rapid self-heating synthesis of Fe-based nanomaterial catalyst for advanced oxidation. Nat. Commun. 14, 4975 (2023).
Li, P. et al. Flash joule heating synthesis of carbon supported ultrafine metallic heterostructures for high-performance overall water splitting. J. Alloy. Compd. 947, 169630 (2023).
Qiu, Y. et al. Hybrid electrocatalyst Ag/Co/C via flash Joule heating for oxygen reduction reaction in alkaline media. Chem. Eng. J. 430, 132769 (2022).
Yao, Y. et al. High temperature shockwave stabilized single atoms. Nat. Nanotechnol. 14, 851–857 (2019).
Zhu, W. et al. Ultrafast non-equilibrium synthesis of cathode materials for Li-ion batteries. Adv. Mater. 35, 2208974 (2023).
Liao, Y. et al. Transient synthesis of carbon-supported high-entropy alloy sulfide nanoparticles via flash Joule heating for efficient electrocatalytic hydrogen evolution. Nano Res. 17, 3379–3389 (2024).
Xia, D. et al. Flash Joule-heating synthesis of MoO nanocatalysts in graphene aerogel for deep catalytic oxidative desulfurization. AIChE J. 70, e18357 (2024).
Wu, Y. et al. Roll-to-roll Joule-heating to construct ferromagnetic carbon fiber felt for superior electromagnetic interference shielding. Carbon 229, 119474 (2024).
Qian, F. et al. Asymmetric active sites originate from high-entropy metal selenides by Joule heating to boost electrocatalytic water oxidation. Joule 8, 2342–2356 (2024).
Dong, H. et al. Flash Joule heating: a promising method for preparing heterostructure catalysts to inhibit polysulfide shuttling in Li–S batteries. Adv. Sci. 11, 2405351 (2024).
Song, J.-Y. et al. Generation of high-density nanoparticles in the carbothermal shock method. Sci. Adv. 7, eabk2984 (2021).
Li, G. et al. Flash Joule heating to enhance water oxidation of hematite photoanode via mediating with an oxidized carbon overlayer. Carbon 215, 118444 (2023).
Zhang, L. et al. Sub-second ultrafast yet programmable wet-chemical synthesis. Nat. Commun. 14, 5015 (2023).
Deng, J. et al. Programmable wet-interfacial Joule heating to rapidly synthesize metastable protohematite photoanodes: metal and lattice oxygen dual sites for improving water oxidation. ACS Catal. 14, 10635–10647 (2024).
Chen, W. et al. Battery metal recycling by flash Joule heating. Sci. Adv. 9, eadh5131 (2023).
Chen, W. et al. Flash recycling of graphite anodes. Adv. Mater. 35, 2207303 (2023)
Lu, J. et al. Millisecond conversion of photovoltaic silicon waste to binder-free high silicon content nanowires electrodes. Adv. Energy Mater. 11, 2102103 (2021).
Deng, B. et al. Flash separation of metals by electrothermal chlorination. Nat. Chem. Eng. 1, 627–637 (2024).
Zhu, X.-H. et al. Recycling valuable metals from spent lithium-ion batteries using carbothermal shock method. Angew. Chem. Int. Ed. 62, e202300074 (2023).
Wang, J. et al. Toward direct regeneration of spent lithium-ion batteries: a next-generation recycling method. Chem. Rev. 124, 2839–2887 (2024).
Dong, S. et al. Ultra-fast, low-cost, and green regeneration of graphite anode using flash joule heating method. EcoMat 4, e12212 (2022).
Ji, Y. et al. Regenerated graphite electrodes with reconstructed solid electrolyte interface and enclosed active lithium toward >100% initial coulombic efficiency. Adv. Mater 4, e2312548 (2024).
Huang, P., Zhu, R., Zhang, X. & Zhang, W. A milliseconds flash Joule heating method for the regeneration of spent cathode carbon. J. Environ. Sci. Health A 57, 33–44 (2022).
Yin, Y.-C. et al. Rapid, direct regeneration of spent LiCoO2 cathodes for Li-ion batteries. ACS Energy Lett. 8, 3005–3012 (2023).
Chen, W. et al. Nondestructive flash cathode recycling. Nat. Commun. 15, 6250 (2024).
Wyss, K. M. et al. Converting plastic waste pyrolysis ash into flash graphene. Carbon 174, 430–438 (2021)
Chen, Y. et al. Facilely preparing lignin-derived graphene–ferroferric oxide nanocomposites by flash Joule heating method. Res. Chem. Intermed. 49, 589–601 (2023).
Khopade, K. V., Chikkali, S. H. & Barsu, N. Metal-catalyzed plastic depolymerization. Cell Rep. Phys. Sci. 4, 101341 (2023).
Dong, Q. et al. Depolymerization of plastics by means of electrified spatiotemporal heating. Nature 616, 488–494 (2023).
Selvam, E., Yu, K., Ngu, J., Najmi, S. & Vlachos, D. G. Recycling polyolefin plastic waste at short contact times via rapid Joule heating. Nat. Commun. 15, 5662 (2024).
Amalina, F. et al. Biochar production techniques utilizing biomass waste-derived materials and environmental applications — a review. J. Hazard. Mater. Adv. 7, 100134 (2022).
Jia, C. et al. Graphene environmental footprint greatly reduced when derived from biomass waste via flash Joule heating. One Earth 5, 1394–1403 (2022).
Ding, D., Song, X., Wei, C. & LaChance, J. A review on the sustainability of thermal treatment for contaminated soils. Environ. Pollut. 253, 449–463 (2019).
Gomez, E. et al. Thermal plasma technology for the treatment of wastes: a critical review. J. Hazard. Mater. 161, 614–626 (2009)
Scotland, P. et al. Mineralization of captured per- and polyfluoroalkyl substances at zero net cost using flash Joule heating. Preprint at ChemRxiv https://doi.org/10.26434/chemrxiv-2023-6xj3m (2024)
Wu, X. et al. Joule heating-induced active Mg0 into nano-Mg composites for boosted oxidation and antiviral performance. ACS EST. Eng. https://doi.org/10.1021/acsestengg.3c00614 (2024).
Sun, L. et al. Millisecond self-heating and quenching synthesis of Fe/carbon nanocomposite for superior reductive remediation. Appl. Catal. B: Environ. 342, 123361 (2024).
Jia, C. et al. Joule heating induced reductive iron–magnesium bimetallic nanocomposite for eminent heavy metal removal. ACS EST. Eng. 4, 938–946 (2024)
Du, P. et al. In-situ Joule-heating drives rapid and on-demand catalytic VOCs removal with ultralow energy consumption. Nano Energy 102, 107725 (2022).
Han, Y.-C., Cao, P.-Y. & Tian, Z.-Q. Controllable synthesis of solid catalysts by high-temperature pulse. Acc. Mater. Res. 4, 648–654 (2023).
Sahoo, P. K., Kim, K., Powell, M. A. & Equeenuddin, S. M. Recovery of metals and other beneficial products from coal fly ash: a sustainable approach for fly ash management. Int. J. Coal Sci. Technol. 3, 267–283 (2016).
Wei, W. et al. Thermally assisted liberation of concrete and aggregate recycling: comparison between microwave and conventional heating. J, Mater. Civil. Eng. 33, 04021370 (2021).
FJH PATENTS
Method for recovering rare earth in waste FCC (fluid catalytic cracking) catalyst through Joule heat flash deconstruction and glycine leaching -- CN120519716tr // CN120519716
The invention relates to a method for recovering rare earth in a waste FCC (Fluid Catalytic Cracking) catalyst through Joule heat flash deconstruction and glycine leaching, which is characterized in that the phase structure of the waste FCC catalyst is deconstructed in a flash and reinforced manner through a Joule heat technology, and the green, low-carbon and efficient recovery of the rare earth is realized by combining glycine selective leaching and oxalic acid precipitation. Compared with an existing recycling technology of rare earth in the waste FCC catalyst, the Joule heat technology is adopted, so that flash heating can be achieved, catalyst lattices can be efficiently destroyed, the deconstruction time of the waste FCC catalyst is greatly shortened, deconstruction energy consumption is greatly reduced, and huge pollution and carbon reduction advantages are achieved; besides, glycine is adopted as a green leaching agent, the leaching efficiency of the rare earth La and Ce reaches up to 95% or above, and rapid, efficient, green and low-carbon recycling of the rare earth La and Ce in the waste FCC catalyst is achieved.
FLASH JOULE HEATING FOR PRODUCTION OF 1D CARBON AND/OR BORON NITRIDE NANOMATERIALS -- US2025236521
Flash Joule heating (FJH) for production of one-dimensional (1D) carbon and/or boron nitride nanomaterials, and 1D materials integrated with 0D, 1D, 2D, and 3D nanomaterials, composites, nanostructures, networks, and mixtures thereof. Such materials produced by FJH include 1D carbon and hybrid nanomaterials, boron nitride nanotubes (BNNTs), turbostratic boron-carbon-nitrogen (BCN), doped (substituted) graphene, and heteroatom doped (substituted) re-flashed graphene.
SYNTHESIS OF HYDROGEN GAS BY FLASH JOULE HEATING -- AU2024251581
Method and systems for the synthesis of hydrogen gas by flash Joule heating, such as synthesizing hydrogen gas from waste plastic materials, other solid materials, or liquid materials by flash Joule heating.
Flash joule heating synthesis method and compositions thereof -- US12054391
Methods for the synthesis of graphene, and more particularly the method of synthesizing graphene by flash Joule heating (FJH). Such methods can be used to synthesize turbostratic graphene (including low-defect turbo stratic graphene) in bulk quantities. Such methods can further be used to synthesize composite materials and 2D materials. Methods for the synthesis of graphene, and more particularly the method of synthesizing graphene by flash Joule heating (FJH). Such methods can be used to synthesize turbostratic graphene (including low-defect turbo stratic graphene) in bulk quantities.
Synthesis of Metallic Glass Nanoparticles by Flash Carbothermic Reactions -- US2025281915
Synthesis of metallic glass nanoparticles and compositions thereof, including, particularly, the kinetically controlled synthesis of glass nanoparticles by flash carbothermic reactions and compositions thereof.
METHODS OF FLASH JOULE HEATING PER- AND POLYFLUORINATED ALKYL SUBSTANCES -- WO2025193245
Methods of flash Joule heating of per- and polyfluorinated alkyl substances and compositions thereof, including, particularly, methods of flash Joule heating of per- and polyfluorinated alkyl substances absorbed on adsorbates in the presence of metal salts and compositions thereof.
METHODS AND SYSTEMS OF FLASH JOULE HEATING OF LIQUIDS -- WO2025097139
Method and systems for flash Joule heating of liquids, particularly, methods and systems for flash Joule heating of liquids for gas capture, carbon/graphene templates (including customizable freestanding carbon/graphene templates), and carbon nanotubes.
METHODS FOR REMEDIATION OF CONTAMINATED SOIL BY RAPID ELECTROTHERMAL MINERALIZATION -- WO2025080651
Methods for remediating soil having persistent and bioaccumulative pollutants, and. more particularly, methods for remediating soil having per- and polyfluorinated alkyl substances (PFAS) and other halogen-containing contaminates by rapid electrothermal mineralization.
ULTRAFAST FLASH JOULE HEATING SYNTHESIS METHODS -- US2024116094
Method and system for soil remediation by flash Joule heating. A contaminated soil that includes organic pollutants and/or one or more metal pollutants can be mixed with carbon black or other conductive additive to form a mixture. The mixture then undergoes flash Joule heating to clean the soil (by the decomposing of the organic pollutants and/or removing of the one or more toxic metals, such as by vaporization).
METHODS OF FLASH-WITHIN-FLASH JOULE HEATING AND SYSTEMS THEREOF -- WO2025042774
Methods of flash-within-flash (FWF) Joule heating and the systems thereof. The FWF Joule heating process subjects outer feedstock in an outer vessel to a flash Joule heating process, whereby the flash Joule heating process upon the outer feedstock results in the conversion of inner feedstock within an inner vessel (which inner vessel is within the outer vessel) to a converted material.
FLASH RECYCLING OF BATTERIES -- US2024120506
Method and system for flash recycling of batteries, including lithium-ion batteries, other metal (sodium, potassium, zinc, magnesium, and aluminum) -ion batteries, metal batteries, batteries having all metal oxide cathodes, and batteries having graphite-containing anodes. The method and system include a solvent-free and water-free flash Joule heating (FJH) method performed upon a mixture that includes materials from the batteries done in millisecond for recycling the materials.. In some embodiments, the FJH method is combined with magnetic separation to recover lithium, cobalt, nickel, and manganese with high yields up to 98%. In some embodiments, the FJH method is followed by rinsing with dilute acid, such a 0.01 M HCl. In other embodiments, the FJH method is utilized to purify the graphite in the battery, such as for use in the anode of the battery.
ULTRAFAST FLASH JOULE HEATING SYNTHESIS METHODS AND SYSTEMS FOR PERFORMING SAME -- US2023374623
Ultrafast flash Joule heating synthesis methods and systems, and more particularly, ultrafast synthesis methods to recover metal from ores, fly ash, and bauxite residue (red mud).
FLASH RECIRCULATION OF BATTERIES -- CN117015880
Methods and systems for flash recycle of batteries, including lithium ion batteries, other metal (sodium, potassium, zinc, magnesium, and aluminum) ion batteries, metal batteries, batteries with all metal oxide cathodes, and batteries with graphite-containing anodes. The methods and systems include a solvent-free and water-free flash Joule heating (FJH) process performed over milliseconds on a mixture including material from a battery to recycle the material. In some embodiments, the FJH process is combined with magnetic separation to recover lithium, cobalt, nickel, and manganese in high yields of up to 98%. In some embodiments, the FJH process is then rinsed with a dilute acid, such as 0.01 M HCl. In other embodiments, the FJH process is used to purify graphite in a battery, such as an anode for the battery.
VARIABLE FREQUENCY DRIVE FOR FLASH JOULE HEATING SYSTEM AND METHOD -- US2023262845
Systems and methods for flash joule heating carbon with variable frequency drives, for the production of graphene. The system includes a flash joule heating system, and a variable frequency drive system for driving the flash joule heating system, wherein the variable frequency drive system is coupled to the flash joule heating system, and is configured to output a pulse-width modulated current. The system and methods may further include sample temperature feedback, to adjust the output of variable frequency drive system.
FLASH JOULE HEATING FOR PRODUCTION OF 1D CARBON AND/OR BORON NITRIDE NANOMATERIALS -- CA3252464
Flash Joule heating (FJH) for production of one-dimensional (1D) carbon and/or boron nitride nanomaterials, and 1D materials integrated with 0D, 1D, 2D, and 3D nanomaterials, composites, nanostructures, networks, and mixtures thereof. Such materials produced by FJH include 1D carbon and hybrid nanomaterials, boron nitride nanotubes (BNNTs), turbostratic boron-carbon-nitrogen (BCN), doped (substituted) graphene, and heteroatom doped (substituted) re-flashed graphene.
SYNTHESIS OF HYDROGEN GAS BY FLASH JOULE HEATING -- AU2024251581
Method and systems for the synthesis of hydrogen gas by flash Joule heating, such as synthesizing hydrogen gas from waste plastic materials, other solid materials, or liquid materials by flash Joule heating.
Method for strengthening iron/vanadium-titanium separation of vanadium-titanium magnetite through Joule heat flash reduction-magnetic separation -- CN120772003
The invention belongs to the technical field of unconventional metallurgy, and provides a Joule heat flash reduction-magnetic separation reinforced vanadium-titanium separation method for vanadium-titanium magnetite. The invention discloses a Joule heat flash reduction-magnetic separation reinforced vanadium-titanium separation method for vanadium-titanium magnetite. The method comprises the following steps: (1) mixing the vanadium-titanium magnetite and a certain amount of carbon source, and heating in Joule heat equipment; and (2) the sample subjected to Joule heat treatment is subjected to ore grinding-magnetic separation, and metal iron powder and vanadium-titanium enrichment are recycled respectively. The method adopts Joule heat flash to reduce the vanadium-titanium magnetite and strengthen the growth of metal iron grains, and has the advantages of low energy consumption, high iron/vanadium-titanium separation efficiency, high recovery rate and the like.
JOULE HEATING METHOD FOR IRON ORE REDUCTION WITH PLASTICS -- WO2025199222
The inventions disclosed herein relate to methods and systems for efficient iron oxide reduction by flash Joule heating of feedstock comprising iron oxide, plastic, and conductive carbon, wherein the plastic is thermally decomposed to hydrogen and solid carbon which act as reducing agents to the iron oxide. Embodiments of the invention further disclose Joule heated iron oxide reduction wherein the hydrogen and solid carbon reducing agents may be replenished by adding more plastic to the feedstock. Embodiments of the invention further disclose Joule heated iron oxide reduction wherein some of the reduced iron and/or some of the solid carbon may be removed and new iron oxide and/or new plastic are added to the feedstock to make the process continuous. Embodiments of the invention further disclose iron oxide reduction by flash Joule heating of feedstock comprising of iron oxide and conductive carbon, wherein the carbon acts as reducing agents to the iron oxide.
Method for preparing lignin hard carbon negative electrode material by Joule thermal flash evaporation -- CN120698437
The invention discloses a method for preparing a lignin hard carbon negative electrode material through Joule thermal flash evaporation, and belongs to the technical field of negative electrode material preparation. The method mainly comprises the following steps: (1) reacting lignin with alkali liquor, adding acid, washing with water, and drying to obtain dried lignin; (2) preheating the dried lignin in a tubular furnace to obtain a hard carbon precursor; and (3) putting the hard carbon precursor into a graphite mold, and carbonizing through Joule heat flash evaporation to obtain the lignin-based hard carbon negative electrode material. According to the method, rapid temperature rise is realized by Joule heating, and the method is short in reaction time and high in reaction temperature. Compared with a radiation cooling mode of a traditional high-temperature furnace, black-body radiation can release most heat within milliseconds. Under the action of an electric field, lignin is recombined and stacked into a vortex layer carbon layer, and a three-dimensional continuous carbon network is formed. The ultrafast method can relieve the carbon layer accumulation phenomenon in the lignin pyrolysis process.
Rapid preparation method of silicon carbide particles based on flash Joule heat process -- CN120681759
The invention provides a rapid preparation method of silicon carbide particles based on a flash Joule heat process, and belongs to the technical field of silicon carbide preparation. Under the condition that complex raw material/precursor treatment is not needed, only raw materials are subjected to simple solid-phase mixing, and on the premise that a catalyst, pretreatment and preheating are not needed, the silicon carbide particles are prepared; a sample is subjected to direct current contact heating by adopting flash Joule thermal equipment (which can be self-made) with low cost, and the silicon carbide micro-nano particles can be successfully prepared within an extremely short time within one second. The method is simple in technological process, extremely low in equipment cost and time cost and high in flexibility, raw materials can be replaced according to actual conditions, even industrial waste containing carbon and silicon can be used as raw materials for preparing silicon carbide, the method has actual application value and industrial potential, and large-scale continuous production can be achieved.
Flash joule heating synthesis method and compositions thereof -- US12054391
Methods for the synthesis of graphene, and more particularly the method of synthesizing graphene by flash Joule heating (FJH). Such methods can be used to synthesize turbostratic graphene (including low-defect turbo stratic graphene) in bulk quantities. Such methods can further be used to synthesize composite materials and 2D materials. Methods for the synthesis of graphene, and more particularly the method of synthesizing graphene by flash Joule heating (FJH). Such methods can be used to synthesize turbostratic graphene (including low-defect turbo stratic graphene) in bulk quantities. Such methods can further be used to synthesize composite materials and 2D materials
Adsorption-enhanced preparation method of biomass tar modified flash graphene -- CN120646820
The invention relates to the technical field of graphene, and discloses an adsorption-enhanced preparation method of biomass tar modified flash graphene, which comprises the following steps: mixing biomass tar with a nitrogen source and an iron source, and pretreating to obtain mixed slurry; freeze-drying the mixed slurry to obtain a dried sample; sequentially carrying out heating treatment on the dried sample in an inert gas atmosphere, heating to a set carbonization temperature at a specific heating rate, and carrying out heat preservation for a preset time, so as to obtain a tar carbon precursor; and carrying out flash Joule heat treatment on the tar carbon precursor. The modified flash evaporation graphene is prepared by taking the biomass tar as a raw material, and high-value utilization of the biomass tar is realized, so that the problem of environmental pollution caused by direct discharge or simple treatment of the biomass tar as a waste is solved, high-value utilization of the biomass tar is realized, and potential harm of a traditional treatment mode to the environment is avoided.
Method for removing heavy metals in waste incineration fly ash based on flash Joule heating technology -- CN120619034
The invention relates to the technical field of garbage treatment, in particular to a method for removing heavy metal in garbage incineration fly ash based on a flash evaporation Joule heating technology, which comprises the following steps: step 1, uniformly mixing the garbage incineration fly ash with a conductive heat-assisting material to obtain a mixture; and 2, the mixture is subjected to flash evaporation Joule heating treatment and cooled, and waste incineration fly ash residues are obtained. According to the method, the flash evaporation Joule heating technology is applied to rapid removal of the heavy metal in the waste incineration fly ash, the fly ash and the conductive heat-assisting material are mixed, and the resistance of the fly ash is set to be smaller than or equal to 3 ohms, so that second-level high-temperature treatment is achieved, and form transformation and efficient volatilization of the heavy metal such as Pb, Zn and Cd are remarkably promoted. According to the technology, the electrical property of the mixture is regulated and controlled through low-voltage pulse pretreatment, and an efficient, low-consumption and green dry-type fly ash heavy metal treatment path is constructed in combination with accurately controlled flash evaporation voltage, time and frequency.
METHODS AND SYSTEMS FOR THE RECOVERY AND REUSE OF CONDUCTIVE ADDITIVES FOR FLASH JOULE HEATING -- WO2024097668
Methods and systems for the recovery and reuse of conductive additives for flash Joule heating. The conductive additives utilized or flash Joule heating for materials such as e-waste, ores, fly ash, soil, and/or bauxite residue can be recovered at high recovery yields greater than 85%, which can then be reused for further flash Joule heating processes. The conductive additives can be separated from the products of the flash Joule heating process, such as by sieving or by centrifugation, filtering, and drying.
Method for extracting germanium from germanium-containing lignite and synchronously preparing hard carbon material -- CN120589728
The invention belongs to the technical field of metallurgy and material preparation, and discloses a method for extracting germanium from germanium-containing lignite and synchronously preparing a hard carbon material. The method comprises the following steps: placing germanium-containing lignite in flash evaporation Joule heat equipment, rapidly heating to 500-3000 DEG C in a vacuum or protective atmosphere by applying current to generate Joule heat for 0.1-10 seconds, then cooling to room temperature, and circulating the heating-cooling procedure for several times to respectively obtain germanium-rich condensate and pyrolysis residues, and carrying out acid leaching and filtering on residues to obtain the hard carbon material. The method for efficiently separating the germanium from the germanium-containing lignite and synchronously preparing the hard carbon material has the advantages of simplicity in operation, low energy consumption, high efficiency, high product value and the like.
Sleeve type flash Joule heating device and heating method -- CN120557943
The invention provides a sleeve type flash Joule heating device and a heating method. The sleeve type flash Joule heating device comprises a conductive sleeve, a reaction raw material and a power supply system, the conductive sleeve is used for loading reaction raw materials, and conductive materials or conductive structures are arranged in the reaction raw materials; the power supply system is connected with the sleeve to form a first heating branch; the power supply system is connected with the reaction raw materials to form a second heating branch; the power supply system is suitable for providing direct current; the power supply system comprises a direct-current high-voltage pulse controller, and the direct-current high-voltage pulse controller is suitable for controlling on-off of a first heating branch and a second heating branch. The second heating branch is provided with a time delay relay so as to be suitable for controlling the conduction time sequence of the second heating branch. According to the invention, the inner and outer independent Joule heating loops are constructed, the outer conductive sleeve Joule is utilized to preheat the reaction raw material, the inner branch is started to perform flash Joule heating, and the temperature uniformity of the thermal field can be improved by utilizing the double-thermal-field coupling design.
Zinc oxide fine grain ceramic sintering method based on room temperature flash sintering -- CN119638402
The invention relates to a zinc oxide fine grain ceramic sintering method based on room temperature flash sintering, which comprises the following steps: (1) placing a zinc oxide ceramic green body in room temperature air, and spraying a layer of black insulating material on the surface layer of the green body; respectively arranging positive and negative electrodes at two ends of the ceramic green body, and connecting the positive and negative electrodes to a power supply through wires; the ceramic green body is wrapped by using a black thermal insulation material as a sheath; (2) turning on a power supply, increasing the voltage until the ceramic green body generates a milliampere-level micro current, then keeping the voltage unchanged, and continuously increasing the temperature of the ceramic green body under the action of Joule heat and heat preservation of the micro current; and (3) after the temperature of the ceramic green body rises to a target temperature, further increasing the voltage to enable the current of the ceramic green body to rise to a target current density value, keeping for a target duration, and then turning off the power supply to obtain the zinc oxide fine-grain ceramic. Compared with traditional low-voltage flash burning of zinc oxide, a heating furnace body is not needed to provide excitation temperature, and complexity of an experimental device and an operation process is avoided.
Natural mineral-based wave-absorbing material synthesized based on flash sintering process -- CN120081420
The invention discloses a natural mineral-based wave-absorbing material synthesized based on a flash sintering process and a preparation method of the natural mineral-based wave-absorbing material, and relates to the technical field of wave-absorbing materials. Molybdenite powder and ferric oxide powder are fully and uniformly mixed in a mortar, and a mixed raw material is obtained; putting the mixed raw material into a corundum ring, connecting a platinum wire and fixing; placing the corundum ring in a muffle furnace, heating, connecting a platinum wire with a power supply, and carrying out flash burning; and naturally cooling to obtain a product, namely the MoS2/Fe3O4/MoO2 composite wave-absorbing material. Natural molybdenite is used as a raw material and is mixed with ferric oxide powder, a flash sintering process is adopted, and in the process, current passes through a sample to generate Joule heat, so that the temperature of the sample is rapidly increased, substance transmission is promoted, rapid reaction of the sample and the molybdenite is promoted, and rapid densification of the sample is caused, so that preparation of the MoS2/Fe3O4/MoO2 composite wave-absorbing material is realized. The production cost is reduced while the preparation efficiency is improved, and the environmental pollution is reduced.
Method for synthesizing magnesium aluminate spinel powder based on flash Joule heat -- CN119707477
The invention discloses a natural mineral-based wave-absorbing material synthesized based on a flash sintering process and a preparation method of the natural mineral-based wave-absorbing material, and relates to the technical field of wave-absorbing materials. Molybdenite powder and ferric oxide powder are fully and uniformly mixed in a mortar, and a mixed raw material is obtained; putting the mixed raw material into a corundum ring, connecting a platinum wire and fixing; placing the corundum ring in a muffle furnace, heating, connecting a platinum wire with a power supply, and carrying out flash burning; and naturally cooling to obtain a product, namely the MoS2/Fe3O4/MoO2 composite wave-absorbing material. Natural molybdenite is used as a raw material and is mixed with ferric oxide powder, a flash sintering process is adopted, and in the process, current passes through a sample to generate Joule heat, so that the temperature of the sample is rapidly increased, substance transmission is promoted, rapid reaction of the sample and the molybdenite is promoted, and rapid densification of the sample is caused, so that preparation of the MoS2/Fe3O4/MoO2 composite wave-absorbing material is realized. The production cost is reduced while the preparation efficiency is improved, and the environmental pollution is reduced.
Equipment and method for preparing graphene by plasma-assisted flash Joule heat -- CN119591095
The invention discloses equipment and a method for preparing graphene by plasma-assisted flash Joule heat. The equipment comprises a central control system, a vacuum system, a signal acquisition system, a power supply system and a tubular rotary reaction device, the central control system is mainly used for issuing and controlling instructions of each area of the equipment; the vacuum system is used for controlling the vacuum degree required by the reaction and is monitored by a vacuum meter in real time; the signal acquisition system acquires temperature, voltage and current during reaction in real time and inputs the temperature, voltage and current to the central control system; the power supply system provides electric energy for the tubular rotary reaction device; the tubular rotary reaction device is used for placing a sample and generating plasma, so that the sample is subjected to uninterrupted plasma treatment and flash Joule heat treatment. According to the equipment, plasma-Joule heat is continuously carried out, a powdery sample can be fully treated, and the problem that the purity of a product after flash evaporation is too poor due to excessive material impurities before heating of traditional Joule heat equipment is remarkably solved.
Integrated equipment and method for simultaneously preparing graphene and silicon carbide nanowire by using flash Joule thermal method -- CN119591096
The invention discloses an integrated device and method for simultaneously preparing graphene and silicon carbide nanowires through a flash evaporation Joule thermal method. Comprising a vacuum system, a detection system, a central control system, a discharge system, a heating pipe, a reaction pipe and a deposition pipe. The vacuum system provides a vacuum environment and fixes a reaction sample; the detection system monitors reaction data and transmits the data to the central control system; the central control system receives and records reaction data, controls discharging parameters and sends a charging and discharging command; the discharging system receives the charging and discharging command to discharge the heating pipe; the heating tube performs discharge reaction, current generates joule heat through a conductive carbon source in the tube, and heat is transferred into the reaction tube and the deposition tube through heat transfer; the reaction tube absorbs heat to heat a mixed carbon source and a silicon source stored in the reaction tube, and the top of the reaction tube is provided with a row of small circular-truncated-cone-shaped holes communicated with the deposition tube; the deposition tube collects reaction tube gas, and the tube wall is coated with a catalyst for reactant deposition and growth. The method is suitable for simultaneously preparing the graphene and the silicon carbide nanowire.
COMPOSITIONS, SYSTEMS AND METHODS FOR FLASH JOULE HEATING CARBON NANOTUBES -- WO2025039082
A system and method for a conversion of plastic and carbon feedstock resulting in a hybrid morphology of carbon nanotubes is provided herein. The system includes a feedstock containing a plastic, a conductive carbon, and a metal-based catalyst. The system further includes a plurality of graphite electrodes configured to conduct a current through the feedstock. The system further includes a reservoir configured to contain the feedstock while allowing outgassing during the conversion. The system further includes a chamber configured to contain combustible volatile substances. The system further includes a power source configured to provide electrical power for the conversion. The system further includes an electrical controller configured to use a feedback mechanism for controlling the conversion and growth of the carbon nanotubes.
Integrated equipment and method for preparing ferrite-microwave dielectric ceramic composite substrate by using flash Joule thermal method -- CN119362000
The invention discloses integrated equipment and method for preparing a ferrite-microwave dielectric ceramic composite substrate by using a flash Joule thermal method. The integrated equipment comprises a central control system, an identification camera, a path planning system, a Joule heating system, a base station, a preheating system, a reaction chamber and a conductive clamp. The central control system is mainly used for storing process parameters, receiving scanning signals and sending commands; the path planning system executes a command planning path set by the central system; the Joule heating system is used for charging and discharging a capacitor and is connected with the central control system to release electricity for positive and negative electrodes in real time; a resistance wire is wrapped outside the base to preheat the material, copper wires are arranged at the bottom of the base in a manner of penetrating through array apertures, and a copper sheet is welded at the upper part to improve the conductive area; quartz glass is arranged outside the reaction chamber, the upper cover plate and the lower cover plate can axially move to fix the reaction position, and the conductive clamp is used for non-conductive ferrite materials. According to the invention, the ferrite and the microwave dielectric ceramic can be quickly connected to prepare the composite substrate with excellent electromagnetic performance.
METHODS AND SYSTEMS OF FLASH JOULE HEATING OF LIQUIDS -- WO2025097139
Method and systems for flash Joule heating of liquids, particularly, methods and systems for flash Joule heating of liquids for gas capture, carbon/graphene templates (including customizable freestanding carbon/graphene templates), and carbon nanotubes.
Biomass carbon-based composite material prepared by Joule hot method in flash macro-quantity manner -- CN118996481
The invention discloses a biomass carbon-based composite material prepared by a Joule heat method in a flash macro-quantity manner and application thereof, and relates to the technical field of electro-catalytic materials. According to the method, a Joule rapid heating method is adopted, corn straw is selected as a raw material, a nitrogen source and a nickel source are introduced, the functional biomass carbon-based composite material is prepared in a flash macro-quantity mode, and the catalyst is used for the field of electrocatalytic CO2 reduction and shows excellent catalytic performance; in addition, the technology is green and environment-friendly, the raw materials used in the technology are cheap and easily available, the treatment time is short, the reaction is mild, the energy consumption is low, the method has very high application value and very good application prospect, the whole preparation process has very high yield, the operation is simple, the repeatability is good, the controllability is strong, the method is green and environment-friendly, and the method is beneficial to industrial large-scale production.
Metal boride electrolyzed water catalyst and flash evaporation Joule heat technology preparation method -- CN118387891
The invention provides a metal boride electrolyzed water catalyst and a flash evaporation Joule heat technology preparation method, and relates to the technical field of inorganic functional materials, a solid powder precursor is obtained through one-step grinding, then metal boride is obtained in a gas atmosphere in a flash evaporation Joule heat heating mode, RuB2 is optimal, and in an acid solution, RuB2 is optimal, and the metal boride can be prepared into the metal boride catalyst through the flash evaporation Joule heat technology. According to the present invention, the current density can achieve 10 mA/cm < 2 >, the required overpotential is as low as 15 mV, the catalytic performance can be stabilized for more than 20 h, and the catalyst has high catalyst activity and high stability. According to the catalyst, the hydrogen evolution overpotential of the boride is reduced, and meanwhile, the generation of crystalline nanocrystals can be promoted due to the rapid cooling rate, so that the stability of the catalyst in a water electrolysis hydrogen evolution reaction is improved. According to the metal boride electrolyzed water catalyst and the flash evaporation Joule heat technology preparation method provided by the invention, the preparation time and the energy consumption can be reduced, and the pure-phase metal boride can be prepared.
FLASH SINTERING -- US2023278932
A method of performing a flash sintering of a specimen (200, 300, 400, 600), the method comprising: connecting an anode electrode (102) to a specimen (200, 300, 400, 600) at an anode contact and connecting a cathode electrode (102) to the specimen (200, 300, 400, 600) at a cathode contact; flowing current through the specimen (200, 300, 400, 600) from the anode electrode (102) to the cathode electrode (102) to heat the specimen (200, 300, 400, 600) by Joule heating and thereby sinter it; wherein at least one of the anode contact and the cathode contact is configured to reduce a temperature gradient between a core (110, 610) in a central region of the specimen (200, 300, 400, 600) and a surface (120, 620) of the specimen (200, 300, 400, 600).FIG. 2 is to be reproduced with the Abstract.
ULTRAFAST FLASH JOULE HEATING SYNTHESIS METHODS -- CA3209120
Method and system for soil remediation by flash Joule heating. A contaminated soil that includes organic pollutants and/or one or more metal pollutants can be mixed with carbon black or other conductive additive to form a mixture. The mixture then undergoes flash Joule heating to clean the soil (by the decomposing of the organic pollutants and/or removing of the one or more toxic metals, such as by vaporization).
Needle electrode discharge tube suitable for flash Joule heating process and Joule heating equipment -- CN115318219
The invention belongs to the technical field of electrical equipment, and particularly relates to a needle-shaped electrode discharge tube suitable for a flash joule heating process and joule heating equipment, the needle-shaped electrode discharge tube comprises an upper electrode, an upper tube body, a lower tube body and a lower electrode, and the upper electrode and the lower electrode (the needle-shaped electrode is formed on the part, located in the tube body, of each of the upper electrode and the lower electrode; the Joule heating equipment comprises a cart type rack, and a parallel capacitor bank is installed on the lower layer in the cart type rack. The middle layer is provided with a vacuum pump, a direct current contactor, an adjustable power inductor, a power resistor, a fly-wheel diode, a silicon controlled rectifier power supply and a low-voltage switching power supply; one end of an electrode of the direct current contactor is connected with the anode of the shunt capacitor bank through a wire, and the other end is connected with the adjustable power inductor through a wire; the upper layer is provided with a vacuum experiment module which is internally provided with a discharge clamp. The Joule heating equipment provided by the invention is ultrahigh voltage discharge heating equipment, and has the characteristics of controllable discharge energy, discharge voltage and discharge time.
Method for purifying quartz sand through flash Joule heat treatment -- CN118359200
The invention relates to a method for purifying quartz sand through flash Joule heat treatment, and belongs to the field of quartz sand purification, the purification method adopts coarsely purified quartz sand as a raw material, and comprises the following steps: (1) ball milling and screening; (2) flash Joule heat treatment; (3) carrying out inorganic mixed acid leaching; (4) washing and drying; and (5) high-temperature chloridizing roasting. According to the invention, by utilizing the characteristic of extremely high heating and cooling speed of the flash Joule heat treatment technology, extremely hot and extremely cold treatment of the quartz sand is completed within several seconds, so that a large amount of inclusion in the quartz sand bursts, the purification efficiency of the quartz sand is greatly improved, and huge energy consumption caused by long-time heating and cooling treatment is effectively saved; the purification effect of the quartz sand is improved. The method is simple and easy to operate and popularize, and has obvious economic and practical values.