Bismuth clusters pinned on TiO₂ porous nanowires boosting charge transfer for CO₂ photoreduction to CH₄

Artificial photosynthesis in carbon dioxide (CO₂) conversion into value-added chemicals attracts considerable attention but suffers from the low activity induced by sluggish separation of photogenerated carriers and the kinetic bottleneck-induced unsatisfied selectivity. Herein, we prepare a new-style Bi/TiO₂ catalyst formed by pinning bismuth clusters on TiO₂ nanowires through being confined by pores, which exhibits high activity and selectivity towards photocatalytic production of CH₄ from CO₂. Boosted charge transfer from TiO₂ through Bi to the reactants is revealed via in situ X-ray photon spectroscopy and time-resolved photoluminescence (PL). Further, in situ Fourier transform infrared results confirm that Bi/TiO₂ not only overcomes the multi-electron kinetics challenge of CO₂ to CH₄ via boosting charge transfer, but also facilitates proton production and transfer as well as the intermediates *CHO and *CH₃O generation, ultimately achieving the tandem catalysis towards methanation. Theoretical calculation also underlies that the more favorable reaction step from *CO to *CHO on Bi/TiO₂ results in CH₄ production with higher selectivity. Our work brings new insights into rational design of photocatalysts with high performance and the formation mechanism of CO₂ to CH₄ for solar energy storage in future.