Enhanced Electrochemical H2O2 Production via Two-Electron Oxygen Reduction Enabled by Surface-Derived Amorphous Oxygen-Deficient TiO2–x

The electrochemical oxygen reduction reaction (ORR) is regarded as an attractive alternative to the anthraquinone process for sustainable and on-site hydrogen peroxide (H2O2) production. It is however hindered by low selectivity due to strong competition from the four-electron ORR and needs efficient catalysts to drive the 2e– ORR. Here, an acid oxidation strategy is proposed as an effective strategy to boost the 2e– ORR activity of metallic TiC via in-site generation of a surface amorphous oxygen-deficient TiO2–x layer. The resulting a-TiO2–x/TiC exhibits a low overpotential and high H2O2 selectivity (94.1% at 0.5 V vs reversible hydrogen electrode (RHE)), and it also demonstrates robust stability with a remarkable productivity of 7.19 mol gcat.–1 h–1 at 0.30 V vs RHE. The electrocatalytic mechanism of a-TiO2–x/TiC is further revealed by density functional theory calculations.