Platinum-Supported Indium Tin Oxide Catalyst for Efficient H₂O₂ Production via Two-Electron Water Oxidation Reaction

The two-electron water oxidation reaction (2e– WOR) has drawn growing attention as a potential method of producing hydrogen peroxide (H2O2) on-site through electrochemical water splitting. Nevertheless, despite ongoing efforts to identify more effective electrocatalysts for 2e– WOR, it remains a challenge to simultaneously achieve good activity, selectivity, and stability with a single catalyst material. In the field of thermocatalysis, metal oxide supports have been used to tune the catalytic properties of the supported metal catalysts. Inspired by this support effect, herein, we explore using the inverse structure─a metal-supported metal oxide bilayer─as the electrocatalyst for 2e– WOR. The metal underlayer modifies the top metal oxide catalytic properties by forming a Mott–Schottky junction, where the built-in potential influences the electron transport. We investigated several semiconducting metal oxide catalysts and different metal support materials and observed a strong metal substrate effect on the metal oxide catalytic activity. We found that a thin layer of indium tin oxide (ITO) supported by a layer of platinum (Pt) shows the best catalytic ability toward 2e– WOR, which is significantly more active and stable than the unsupported ITO catalyst, and its H2O2 production rates are also greater than most reported single component electrocatalysts in the literature. The method of metal underlayer provides a pathway to create future catalysts for this electrochemical reaction.