Zn/N/S Co-doped hierarchical porous carbon as a high-efficiency oxygen reduction catalyst in Zn–air batteries

Zn–N–C catalysts have garnered attention as potential electrocatalysts for the oxygen reduction reaction (ORR). However, their intrinsic limitations, including poor activity and a low density of active sites, continue to hinder their electrocatalytic performance. In this study, we have devised a dual-template strategy for the synthesis of Zn, N, S co-doped nanoporous carbon-based catalysts (Zn–N/S–C(S, Z)) with a substantial specific surface area and a graded pore structure. The introduction of S enhances electron localization around the Zn–Nx active centers, facilitating interactions with oxygen-containing substances. The resulting Zn–N/S–C(S, Z) sample exhibits outstanding performance in an alkaline solution, demonstrating a half-wave potential of 0.89 V. This value surpasses that of commercial Pt/C by 40 mV. Furthermore, when combined with RuO2 (Zn–N/S–C(S, Z) + RuO2), the catalyst demonstrates exceptional performance in a Zn–air battery, offering an open-circuit voltage (OCV) of 1.47 V and a peak power density of 290.8 mW cm−2. This study paves the way for the development of highly dispersed and highly active Zn-metal site catalysts, potentially replacing traditional Pt-based catalysts in various electrochemical devices.