Dynamic Active Sites in Bi 5 O 7 I Promoted by Surface Tensile Strain Enable Selective Visible Light CO 2 Photoreduction.

Surface defects with abundant localized electrons on bismuth oxyhalide catalysts are proved to have the capability to capture and activate CO 2 . 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 CO 2 photoreduction, but is a universal challenge. In this work, the Bi 5 O 7 I nanotubes with surface tensile strain are synthesized, which are favorable for the visible light-induced dynamic I defects generation. The CO 2 molecules absorbed on I defects are constantly reduced by the incoming photogenerated electrons from I-deficient Bi 5 O 7 I nanotubes and the successive protonation of CO 2 molecules is thus highly promoted, realizing the selective CO 2 conversion process via the route of CO 2 -COOH - -CO. The efficient and stable photoreduction of CO 2 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 CO 2 photoreduction process and provide a new strategy into rational design of deactivation-resistant catalysts for selective CO 2 photoreduction.