Defect-Rich, Graphenelike Carbon Sheets Derived from Biomass as Efficient Electrocatalysts for Rechargeable Zinc–Air Batteries

Rechargeable Zinc–air batteries (RZABs) have attracted much attention due to their low cost, environmental benignity, high safety, and specific energy density. The bottleneck blocking the large-scale application of RZABs is the high cost and vulnerability of noble metal (Pt, IrO2, and RuO2) electrocatalysts for the oxygen reduction reaction/oxygen evolution reaction (ORR/OER). In this work, using the fruits of glossy privet as raw material, graphenelike and defect-rich carbon sheets with N doping (GPNCS) are produced as a highly active electrocatalyst for RZABs via a nontoxic, scalable, and sustainable biomass strategy. The graphenelike and porous structure of GPNCS enables the material to possess high conductivity and specific surface area, which are beneficial for its good performance as an electrocatalyst. The synergistic effect between N-doping atoms and topological defects endows the GPNCS with remarkable ORR activity and moderate OER performance. The RZABs verify the excellent catalytic performance of GPNCS, with a low charge–discharge voltage gap that remains nearly unchanged after 1340 cycles (about 500 h) at 10 mA·cm–2. This research opens up a new avenue for the cost-effective and large-scale production of highly efficient ORR/OER electrocatalysts for the development of next-generation energy storage and conversion systems.