Construction of Fe, N and S triple-doped carbon nanosheets as bifunctional electrocatalysts for rechargeable zinc-air batteries

The development of effective oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts is essential for the preparation of high-performance rechargeable zinc-air batteries. Porous carbon nanosheets (Fe/NSCN-900) doped with three elements, Fe, N, and S, were prepared from bacterial cellulose using a simple high-speed mixing-impregnation-high-temperature pyrolysis method for use as highly active electrocatalysts in rechargeable zinc-air batteries. The two-dimensional porous structure of Fe/NSCN-900 grants the material a high electrical conductivity and a large specific surface area, which is conducive to catalysis. The synergistic effect between Fe, N, and S elements endows Fe/NSCN-900 with exceptional ORR and OER electrocatalytic properties. The prepared Fe/NSCN-900 showed good bifunctional electrocatalytic activity with an OER overpotential of 310 mV (η 10 = 310 mV vs. RHE) at a current density of 10 mA cm −2 and obtained high ORR onset potential (0.94 V) and half-wave potential (0.82 V). In addition, when a rechargeable zinc-air battery assembled from Fe/NSCN-900 at a current density of 10 mA cm −2 underwent 1200 cycles (over 400 h), the charging and discharging voltage gaps remained nearly unchanged. This research paves the way for the development of high-performance bifunctional electrocatalysts for next-generation energy conversion and storage devices.