Metal single-atom catalysts for photocatalytic H2O2 synthesis

Abstract

Traditional H₂O₂ production methods (e.g., anthraquinone process) suffer from high energy consumption and pollution, whereas photocatalytic synthesis has attracted significant attention due to its environmentally friendly and sustainable characteristics. Through the atomically dispersed active sites and tunable electronic structures, single-atom catalyst (SAC)-based photocatalytic systems demonstrate exceptional performance in enhancing light absorption, promoting charge carrier separation, and regulating reaction selectivity. Notably, the partial SAC photocatalytic system achieves efficient H₂O₂ synthesis via the 2-electron oxygen reduction reaction (2e⁻ ORR) and 2-electron/4-electron water oxidation reaction (2e⁻/4e⁻ WOR) synergistic pathway without sacrificial agents. This work emphasizes the fundamental mechanisms of SACs in light absorption, carrier dynamics, and surface reactions, and systematically compares preparation methods and supports (carbon-based supports, covalent organic frameworks, metal–organic frameworks, metal oxides, etc.) in modulating active site microenvironments and reaction pathway selectivity. Furthermore, this work thoroughly investigates optimization strategies for ORR and WOR synergistic pathways through defect engineering, heteroatom doping, functional group modification, heterojunction construction, and cocatalyst synergy. Moreover, current technical bottlenecks of SACs in photocatalytic H₂O₂ synthesis are critically addressed with proposed improvements, along with perspectives on future research priorities. This comprehensive analysis aims to establish a theoretical framework for the rational design of SACs and accelerate the practical development of photocatalytic H₂O₂ synthesis technology.