Strategies for enhancing catalytic performance of single-atom catalysts in 2e-oxygen reduction reaction: A review

Abstract

The electrocatalytic two-electron oxygen reduction reaction (2e– ORR) is an effective method for synthesizing hydrogen peroxide under ambient temperature and pressure, which offers advantages such as operational safety and low cost. Single-atom catalysts (SACs) consist of individual metal atoms dispersed on a support, allowing for high structural tunability and cost-effectiveness. Notably, the unsaturated coordination environments and unique electronic structures of SACs significantly enhance their catalytic activity, while isolated active sites improve selectivity for hydrogen peroxide. Consequently, SACs have attracted considerable research interest in the field of 2e– ORR in recent years, leading to significant advancements. This paper first outlines the mechanisms and pathways of the 2e– ORR, as well as the structural design principles of SACs. It then summarizes modulation strategies for SACs, focusing on the selection of metal atoms, optimization of the coordination environment, and modification of the support. Furthermore, the paper discusses how these strategies influence the catalytic activity, selectivity, and stability of SACs. Finally, it highlights the limitations of SACs in 2e– ORR research, including inadequate catalytic performance, insufficient mechanistic studies, and challenges in synthesis, while proposing potential solutions and future research directions.