Flash Joule Heating (FJH) is a powerful synthesis technique that uses a high-voltage electrical discharge to rapidly heat conductive materials to temperatures exceeding 3,000 K (approx. 2,725°C) in less than a second. Originally popularized by the Tour Group at Rice University, this method is primarily used to convert carbon sources (like coal, plastic waste, or petroleum coke) into high-quality turbostratic graphene.

The key components of the flash joule heating machine are: (1) Capacitor Bank: Stores a massive amount of electrical energy to be released in a quick "flash." (2) Electrodes: Usually made of graphite or copper, these compress the sample. (3) Reaction Chamber: A high-pressure quartz or ceramic tube that contains the precursor material. (4) Control System: Regulates the discharge time (typically 10–500 milliseconds) and the voltage applied.

The main features are (1) Speed: While traditional Chemical Vapor Deposition (CVD) or furnace heating takes hours, FJH takes milliseconds. (2) Turbostratic Graphene: Unlike AB-stacked graphene (which tends to clump), FJH produces "turbostratic" graphene. The layers are misaligned, making them much easier to peel apart (exfoliate) and disperse in composites or battery slurries. (3) Sustainability: It can "upcycle" low-value waste (tires, food waste, mixed plastics) into high-value graphene without using solvents or high-purity gases. (4) Material Diversity: Beyond graphene, it is used to synthesize metal nanoparticles, phase-change materials, and specialized ceramics for solid-state batteries.

References:

L Eddy, et al., Electric Field Effects in Flash Joule Heating Synthesis, J. Am. Chem. Soc. 2024, 146, 23, 16010–16019

B. Deng, et al., Flash Joule heating for synthesis, upcycling and remediation, Nature Reviews Clean Technology, 2025, 1, 32–54