Unraveling the Synergistic Role of Oxygen Vacancies and Pt Nanoparticles in Mixed-Phase TiO2 for Efficient Photocatalytic CO2 Reduction

Photocatalytic CO 2 reduction is a promising approach to close the carbon cycle by converting CO 2 into high-value chemicals and fuels, but its practical advancement is hindered by key challenges in photocatalyst design. Though oxygen vacancies (O V ) engineering and noble metal co-catalysts can enhance performance via synergistic strong metal-support interactions (SMSI), their use is limited by harsh synthesis conditions and noble metal cost. Herein, we integrated Pt nanoparticle (Pt NPs )-loaded mixed-phase TiO 2 (anatase/rutile) with abundant O V via a facile two-step method. The as-prepared Pt/A2-TiO 2-x exhibited CH 4 and CO production rates of 72.31 and 55.45 μmol·g⁻¹·h⁻¹ in pure H 2 O, representing 5.6- and 9-fold enhancements over pristine TiO 2 . Characterizations, theoretical calculations, and in-situ Fourier transform infrared spectroscopy confirmed that O V facilitated robust Pt-TiO 2 SMSI, which promoted bulk photogenerated electron migration to Pt surfaces and accelerated CO 2 adsorption/activation, thereby optimizing the CO 2 -to-CH 4 reaction pathway. This work deepens understanding of metal-vacancy synergy and provides a rational strategy for designing cost-effective, high-performance photocatalysts for CO 2 reduction.