Electronic Structure Regulation of Single-Atom Catalysts for Electrochemical Oxygen Reduction to H₂ O₂

Electrochemical synthesis of hydrogen peroxide (H₂ O₂ ) via the 2-electron oxygen reduction reaction (ORR) has emerged as a promising alternative to the energy-intensive anthraquinone process and catalysts combining high selectivity with superior activity are crucial for enhancing the efficiency of H₂ O₂ electrosynthesis. In recent years, single-atom catalysts (SACs) with the merits of maximum atom utilization efficiency, tunable electronic structure, and high mass activity have attracted extensive attention for the selective reduction of O₂ to H₂ O₂ . Although considerable improvements are made in the performance of SACs toward the 2-electron ORR process, the principles for modulating the catalytic properties of SACs by adjusting the electronic structure remain elusive. In this review, the regulation strategies for optimizing the 2-electron ORR activity and selectivity of SACs by different methods of electronic structure tuning, including the altering of the central metal atoms, the modulation of the coordinated atoms, the substrate effect, and alloy engineering are summarized. Finally, the challenges and future prospects of advanced SACs for H₂ O₂ electrosynthesis via the 2-electron ORR process are proposed.