Efficient Electrochemical Reforming of Water-Insoluble C-Only Plastic Wastes

We report here the efficient electrochemical reforming of hydrocarbon polymer wastes, i.e. composed of C–C and C–H bonds only, in aqueous solution at 3 V. Anodic degradation of these chemically resilient wastes is achieved with Faradaic efficiencies of up to 32% on a Ni/Sb-doped SnO₂ electrode. The hydrophobic plastic particles, initially present as large aggregates, are solubilized during the early stages of the reaction, which is essential to achieve high reforming efficiencies. Cathodic H₂ generation is demonstrated with Faradaic and energy efficiencies of up to 57% and 30%, respectively. Under optimized conditions, electroreforming requires ca. 0.10 kWh/g of plastic degraded, which is >120 times more efficient than that previously reported on boron-doped diamond anodes. If scaled up, energy costs as low as ca. 2000$/ton could be achieved, while the H₂ generated could cover up to ca. 70% of these costs. CO₂ emissions, expected to be ranging from 1.65 to 13.02 kg_CO2eq/kg_H2, are competitive with conventional plastic-to-H₂ high-temperature processes. Our results support the industrial potential of plastic electroreforming to efficiently treat chemically resilient plastic wastes.