Synthesis and Performance of Multifunctional Cobalt‐Doped Polydopamine‐Derived Carbon‐Based Electrocatalysts

The escalating global energy crisis underscores the urgent need to develop advanced energy conversion and storage technologies. However, zinc‐air batteries are hindered by the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), necessitating the development of low‐cost, non‐precious metal catalysts to enhance their reaction efficiency. Meanwhile, although the nitrate electroreduction reaction offers a greener alternative compared to the traditional Haber–Bosch process for ammonia synthesis, it also requires the assistance of efficient electrocatalysts. This study advances the ORR, OER, and nitrate reduction reaction (NO 3 RR) technologies through a multifunctional non‐precious metal catalyst–a cobalt, sulfur, and nitrogen co‐doped carbon composite (Co, S, N‐C) synthesized via a surfactant‐assisted method. The catalyst exhibits excellent bifunctional ORR/OER activity, with a half‐wave potential of 0.818 V versus reversible hydrogen electrode for ORR and an overpotential of 431 mV at 10 mA cm −2 for OER. When integrated into a zinc–air battery as the air cathode, it delivers a peak power density of 82.5 mW cm −2 and demonstrates stable cycling performance over 100 h, with a negligible voltage gap increase of only 0.04 V. For NO 3 RR, the catalyst achieves a high NH 3 production rate of 552.1 μmol h −1 cm −2 and a Faradaic efficiency of 94.2% after 1 h of electrolysis in 0.1 M KNO 3 and 0.5 M K 2 SO 4 electrolyte. These results highlight the potential of Co, S, N‐C as a versatile platform for sustainable energy and environmental applications.