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.