Recent Advances in Carbon-Based Bifunctional Oxygen Catalysts for Zinc-Air Batteries

Zinc-air batteries (ZABs) have recently received tremendous research attention due to their high theoretical energy densities. However, current ZABs suffer from poor energy efficiency and cyclability, mainly owing to the sluggish kinetics of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) on the air electrode. Therefore, rational design of efficient bifunctional oxygen electrocatalysts with high activity and stability is essential for improving battery performance. Carbon-based nanomaterials are promising candidates for bifunctional oxygen catalysis. In this review, we present the latest development of carbon-based bifunctional electrocatalysts for ZABs. Firstly, the related reaction mechanisms of bifunctional ORR/OER catalysts are introduced. Then, the recent advances in developing carbon-based bifunctional catalysts with tailored structure and promising catalytic performance are introduced following the regulation strategies, e. g., heteroatom doping, defect engineering, and/or hybridizing with other active materials. Finally, the key challenges and perspectives of advanced ZABs are provided to better shed light on future research.