ZnO As an Active and Selective Catalyst for Electrochemical Water Oxidation to Hydrogen Peroxide

Electrochemical synthesis of hydrogen peroxide (H₂O₂) via two-electron water oxidation reaction (2e-WOR) is an ideal process for delocalized production for water cleaning and other applications. Previously observed water oxidation catalysts have limited activity and selectivity, imposing a bottleneck for broad adoption of this technology. We determine ZnO as a new stable, nontoxic, active, and selective catalyst for 2e-WOR to generate H₂O₂. Using density functional theory calculations, we propose that the (1010) facet of ZnO is an effective catalyst for 2e-WOR and confirm the prediction experimentally. We synthesize ZnO nanoparticles with a high fraction of (1010) facets and find that this catalyst gives an overpotential of 40 mV at 0.1 mA/cm² and peak Faradaic efficiency of 81% toward H₂O₂ evolution.