Atomic Tuning of Metal-Support Interactions for Pathway-Selective CO₂ Photoreduction on TiO₂

Photocatalytic CO₂ conversion demands precise control over multielectron reaction pathways to achieve selective solar fuel production. Atomically dispersed Fe and Cu catalysts on TiO₂ direct divergent photoreduction outcomes-CO via Fe and CH₄/C₂H₆ via Cu-through modulation of CO intermediate binding. Using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray absorption fine structure (XAFS), and density functional theory (DFT) calculations, this study unveils how metal-support interactions reshape electronic structure, stabilize key intermediates, and create oxygen vacancies that enhance CO₂ adsorption in the dark. The Cu sites further promote C─C coupling, enabling multicarbon products under mild conditions. The optimized single-atom catalysts show up to 55.7-fold enhancement in CO and 44.5-fold in CH₄ yields, far surpassing pristine TiO₂. This work illustrates how rational single-atom design can precisely manipulate reaction pathways at the atomic scale, offering a unified framework for selective photoredox catalysis in CO₂ reduction.