Nitrogen-Enriched Porous Carbon Materials from Expanded Polystyrene Waste for Oxygen Reduction Reaction and Rechargeable Zinc-Air Battery

Transforming discardable solid waste like polystyrene (PS) foams into commercially useful applications like sustainable and eco-friendly energy materials has attracted considerable attention. Herein, expanded PS waste is subjected to simple reactions (cross-linking and pyrolysis) to obtain a high-performing electrocatalyst for the oxygen reduction reaction (ORR). The optimized catalyst polystyrene-pyrrole (PSP-800) demonstrates good electrocatalytic ORR activity toward rechargeable zinc-air battery due to its high surface area, copious amount of micropores/mesopores, high nitrogen content, and a trace amount of Fe doping. Accordingly, PSP-800 delivers a high onset potential (0.99 V) and a half-wave potential of 0.88 V versus a reversible hydrogen electrode. Moreover, the rechargeable zinc-air battery using PSP-800 as an ORR catalyst demonstrates improved stability and high-power density (116 mW cm(-2)) compared to the standard Pt/C catalyst.