Enhanced Electrochemical H₂O₂ Production via Two-Electron Oxygen Reduction Enabled by Surface-Derived Amorphous Oxygen-Deficient TiO_2–<i>x</i>

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 TiO_2-<i>x</i> layer. The resulting a-TiO_2-<i>x</i>/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 g_cat.^-1 h^-1 at 0.30 V vs RHE. The electrocatalytic mechanism of a-TiO_2-<i>x</i>/TiC is further revealed by density functional theory calculations.