Defect Engineering of Carbon-based Electrocatalysts for Rechargeable Zinc-air Batteries

Rechargeable zinc-air batteries (ZABs) are considered as one of the most promising electrochemical energy devices due to their various unique advantages. Oxygen electrocatalysis, involving the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), determines the overall performance of zinc-air batteries. Therefore, the development of highly efficient bifunctional ORR/OER catalysts is critical for the large-scale application of ZABs. Carbon-based nanomaterials have been widely reported to be efficient electrocatalysts toward both ORR and OER. The enhanced activity of these electrocatalysts are usually attributed to different doping defects, synergistic effects and even the intrinsic carbon defects. Herein, an overview of the defect engineering in carbon-based electrocatalysts for ORR and OER is provided. The different types of intrinsic carbon defects and strategies for the generation of other defects in carbon-based electrocatalysts are presented. The interaction of heteroatoms doped carbon and transition metals (TMs) is also explored. In the end, the existing challenges and future perspectives on defect engineering are discussed.