Synergistic temperature and sulfur doping engineering of MOF‑derived Co‑N‑C catalysts for high‑performance zinc‑air batteries

This study investigates the synergistic effects of pyrolysis temperature and sulfur doping on the structure and oxygen reduction reaction (ORR) performance of cobalt-based catalysts derived from metal–organic frameworks. Using thiourea as the sulfur source, a series of Co-NSC catalysts were synthesized at different temperatures (750–1050 °C). The results demonstrate that sulfur doping effectively inhibits metal agglomeration by forming Co–S coordination bonds, while an optimal pyrolysis temperature (850 °C) balances defect density, pore structure, and active-site distribution. Among all samples, Co-NSC-850 exhibits favorable ORR activity in alkaline medium, with a half-wave potential of 0.852 V, an electron transfer number close to 4, and H 2 O 2 selectivity below 5%. When applied in zinc-air batteries, Co-NSC-850 delivers a power density of 254.22 mW cm −2 , a small charge–discharge gap (1.02 V), a specific capacity of 809.18 mAh g −1 , and a cycle life of 220 h, comparable to or better than commercial Pt/C. This work provides valuable insights for designing high-performance non-noble metal ORR catalysts through cooperative regulation of temperature and heteroatom doping. Graphical abstract