Recent progress of dual-atom catalysts on zinc-air batteries

Zinc-air batteries (ZABs) are the promising candidates for the novel electrochemical energy storage devices due to their large theoretical specific energy density, high safety and low cost. However, the slow reaction kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in air cathodes limit their practical applications. As an extension of single-atom catalysts (SACs), dual-atom catalysts (DACs), with maximum atom utilization efficiency, high catalytic site loading and tunable active site configurations, are expected to further enhance the ORR/OER catalytic performance, thus becoming a strong candidate for ZABs. In this review, the strategies for introducing bimetallic sites are firstly summarized, then the effects of electronic and geometrical structures of the active centers on the catalytic mechanism are illustrated at the atomic level. In addition, we discuss the roles of DACs as an air cathode catalyst in adjusting the adsorption state of reactant molecules, changing the reaction pathways and lowering the reaction energy barriers of key steps. Finally, the prospects and challenges of DACs in ZABs are envisioned, aiming to provide new ideas for the design of novel bifunctional catalysts in the field of ZABs.