Synergy of Ag and Interfacial Oxygen Vacancies on TiO₂ for Highly Efficient Photocatalytic Production of H₂O₂

Photocatalytic H₂O₂ production stands as a promising sustainable technology for chemical synthesis. However, rapid charge recombination and limited oxygen adsorption by photocatalysts often limit its efficiency. Herein, we demonstrate that the synergy of Ag and interfacial oxygen vacancies on TiO₂ could overcome these challenges. The optimized Ag/TiO₂-50 photocatalyst achieved an impressive H₂O₂ production rate of 12.9 mmol h^-1 g^-1 and maintained a steady-state concentration of 12.8 mM, significantly outperforming most TiO₂-based photocatalysts documented in the literature. Detailed mechanistic studies, aided by TAS, <i>in situ</i> X-ray photoelectron spectroscopy (XPS), and <i>in situ</i> electron paramagnetic resonance (EPR) techniques, indicate that the oxygen vacancies at the Ag-TiO₂ interface act as an interfacial hole trap, inducing a directional hole transfer. This, coupled with Ag acting as an electron acceptor, synergistically boosts the electron-hole separation. Additionally, the increased amount of oxygen vacancies at the Ag-TiO₂ interface of Ag/TiO₂-50 leads to enhanced O₂ adsorption, thus contributing to its superior catalytic performance. This study provides valuable insights into interfacial traps in the charge transfer process and highlights the potential of interface regulation for achieving efficient photocatalytic conversion.