Direct Conversion of Plastic Waste to Graphite at Room Temperature under Air via Solvent-Free Mechanochemistry

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Abstract
Owing to the chemical inertness of sp 3 C–C bonds in polymers, their activation under mild conditions poses a significant barrier to both plastic upcycling and graphitization. Here, we demonstrate a straightforward, solvent-free, one-step mechanochemical method that directly transforms various plastic waste into a critical material, graphite, under ambient conditions (T < 30°C). Facilitated by reactive metals such as Mg, this process requires only ~ 1.8% of the energy input used in traditional methods while delivering graphite with 92% sp 2 carbon content, 80.4% reaction yield, and 15.3% C/O by mol. Both experimental data and theoretical calculations support the formation of carbides and their conversion into graphite, collectively revealing a carbide–graphite pathway that operates without heat, harsh solvents, extreme temperatures, or inert atmospheres, which are traditionally essential. Experiments further reveal that metals more reactive than carbon (Al, Mg, and Ca) can promote the breakdown and graphitization of a wide range of materials, including non-graphitizable, contaminated, and unsorted plastic waste, as well as biomass. This process dramatically reduces thermal energy demands, requiring less than 8% of the input used in pyrolysis and only 1.5% of that required for conventional graphitization. Beyond scalable and safer waste valorization, the resulting graphite functions effectively in Zn-ion batteries and pencils, and establishes a broadly applicable, ambient-temperature platform for carbon waste conversion, opening new directions in solid-state radical chemistry and circular carbon technologies.

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