Engineering the\nAtomic Configurations of Surface-Active\nSites for Retuning the Photoreduction CO<sub>2</sub> Selectivity

The photoreduction of the CO<sub>2</sub> reaction is\na potential\ntechnique for converting solar energy to fuel at room temperature,\nwhich speeds up the recycling and conversion of carbon compounds.\nBased on a highly active photocatalyst, however, disentangling the\nchemical environments of surface structures on the selectivity of\nthe product at the atomic scale is challenging. Herein, we have explored\na sulfur-assisted heat treatment strategy to induce the reconstruction\nfrom surface-ordered line defects to polygonal tungsten line defects,\nchanging the main product from CH<sub>4</sub> (8.2 μmol h<sup>–1</sup>, 5 mg) to CO (13.0 μmol h<sup>–1</sup>, 5 mg) without any additive sacrificial agents. The experimental\nresults reveal that the active sites are the surface terminations\nof the hexagonal-tungsten line defect, where the in-plane-neighboring\nW atoms can break the C–O bonds inside the *COOH intermediates,\nthereby promoting the desorption of CO gas.