Metal-Compound-Based Electrocatalysts for Hydrogen Peroxide Electrosynthesis and the Electro-Fenton Process

Hydrogen peroxide (H2O2) is a powerful oxidant with many applications, but its chemical production is unsustainable and unsafe. Decentralized electrosynthesis of H2O2 via the selective two-electron oxygen reduction reaction (2e– ORR) is attractive, which demands active, selective, stable, and cost-effective electrocatalysts in acidic and neutral solutions where H2O2 is stable. Metal compounds are an emerging class of 2e– ORR catalysts with diverse and tunable structural motifs for optimizing H2O2 electrosynthesis, yet they remain underexplored, with poorly understood structure–property relationships. This Focus Review summarizes the recent computational and experimental developments in metal-compound-based acidic and neutral 2e– ORR catalysts, and the resultant mechanistic understanding and catalyst design rules for guiding future catalyst discoveries. The many fundamental and practical factors at the reaction, catalyst, electrode, and device levels that impact H2O2 electrosynthesis are systematically discussed. Metal-compound-based acidic 2e– ORR catalysts can also enable efficient electro-Fenton processes for environmental remediation and biomass valorization.