Bio-Assisted Atomically Dispersed Fe–N–C Electrocatalyst with Ultra-Low Fe Loading toward pH-Universal Oxygen Reduction Reaction and Neutral Zn-Air Battery

The advancement in the design of non-platinum noble metal-based oxygen reduction reaction (ORR) electrocatalysts with pH universality is crucial for the implementation of renewable energy devices in various environments. In this study, we present a convenient bio-assisted synthesis approach for the preparation of Fe–N–C catalysts, Fe@G-800/100. The Fe–N 4 active sites, distributed atomically in the catalyst, confer remarkable ORR activity, leading to half-wave potentials ( E 1/2 ) of 0.91, 0.70, and 0.83 V vs RHE in alkaline, acidic, and neutral media, respectively. These values surpass the performance of state-of-the-art pH-universal ORR catalysts. We have also demonstrated the feasibility of constructing a cathode for a liquid Zn-air battery (ZAB) by utilizing Fe@G-800/100, with a rarely used PBS-derived neutral electrolyte. The resulting neutral ZAB exhibits a high open-circuit voltage, excellent charge–discharge cycling behavior, and significant specific capacity. Our findings provide valuable observations on the potential of pH-universal Fe–N–C catalysts and a roadmap for the design of neutral ZABs.