Dynamic Active Sites in Bi₅O₇I Promoted by Surface Tensile Strain Enable Selective Visible Light CO₂ Photoreduction

Surface defects with abundant localized electrons on bismuth oxyhalide catalysts are proved to have the capability to capture and activate CO₂. However, bismuth oxyhalide materials are susceptible to photocorrosion, making the surface defects easily deactivated and therefore losing their function as active sites. Construction of deactivation-resistant surface defects on catalyst is essential for stable CO₂ photoreduction, but is a universal challenge. In this work, the Bi₅O₇I nanotubes with surface tensile strain are synthesized, which are favorable for the visible light-induced dynamic I defects generation. The CO₂ molecules absorbed on I defects are constantly reduced by the incoming photogenerated electrons from I-deficient Bi₅O₇I nanotubes and the successive protonation of CO₂ molecules is thus highly promoted, realizing the selective CO₂ conversion process via the route of CO₂-COOH^--CO. The efficient and stable photoreduction of CO₂ into CO with 100% selectivity can be achieved even under visible light (λ >420 nm) irradiation benefited from the dynamic I defects as active sites. The results presented herein demonstrate the unique action mechanism of light-induced dynamic defects during CO₂ photoreduction process and provide a new strategy into rational design of deactivation-resistant catalysts for selective CO₂ photoreduction.