Engineering Fluorine Doping and Ru–Schottky Interfaces in TiO2 for Efficient Photocatalytic CO2 Reduction with H2O

Abstract Photocatalytic CO 2 reduction using H 2 O as the electron donor offers a sustainable pathway for carbon–neutral fuel synthesis; however, its efficiency is limited by sluggish charge separation and insufficient CO 2 activation. Herein, we develop a ruthenium-decorated, fluorine-doped TiO 2 photocatalyst (Ru/F-TiO 2 ) that overcomes these limitations through spatially directed charge modulation and cooperative electronic engineering. Fluorine doping introduces oxygen vacancies that narrow the bandgap and form surface Ti‒F bonds, suppressing charge recombination. Simultaneously, Ru nanoparticles serve as efficient CO 2 adsorption and activation centers while introducing additional surface defects that further strengthen CO 2 binding. The strong coupling between Ru and semiconductor forms a Schottky junction, establishing a strong built-in electric field that promotes directional electron migration toward Ru sites and hole accumulation on F-TiO 2 . Consequently, Ru/F-TiO 2 exhibits outstanding activity and durability, delivering CO and CH 4 production rates of 124.8 and 19.8 μmol/(g·h), respectively. In situ diffuse reflectance infrared Fourier-transform spectroscopy analysis reveals key proton-coupled, multi-electron intermediates, elucidating the reaction pathway. This study demonstrates that the synergistic integration of non-metal doping and metal cocatalyst engineering provides a powerful strategy to regulate charge dynamics and boost solar-driven CO 2 conversion.