Upcycling carbon fibre wastes in solid-flames

Hundreds of thousands of tons of epoxy-containing carbon fibre (CF) wastes are generated from the manufacture of CF reinforced epoxy composites to their end-of-use. Today, most recycling strategies of these CF wastes aim at recovering CFs to the ones as virgin as possible, while techniques for efficiently converting CF wastes to materials of higher value, i.e., upcycling of CF wastes, are underexplored. Here, we develop a solid-flames upcycling technique using Mg and CaCO₃ powders as reactants to convert CF wastes into graphene-grafted CFs (GCFs) and graphene powders within a few seconds. In Mg/CaCO₃ solid-flames, Mg accelerates disconnection of C-O bonds in epoxy resins, promoting interconnection of C-C bonds that lead to the graphene-CF grafting microstructures. This solid-flames upcycling technique, with its superior sustainability metrics and attractiveness in commercial applications including reinforced graphite composites and electromagnetic interference shielding, presents a viable strategy for long-term management of accumulating CF wastes.