Engineering the Atomic Configurations of Surface-Active Sites for Retuning the Photoreduction CO2 Selectivity

The photoreduction of the CO₂ reaction is a potential technique for converting solar energy to fuel at room temperature, which speeds up the recycling and conversion of carbon compounds. Based on a highly active photocatalyst, however, disentangling the chemical environments of surface structures on the selectivity of the product at the atomic scale is challenging. Herein, we have explored a sulfur-assisted heat treatment strategy to induce the reconstruction from surface-ordered line defects to polygonal tungsten line defects, changing the main product from CH₄ (8.2 μmol h^–1, 5 mg) to CO (13.0 μmol h^–1, 5 mg) without any additive sacrificial agents. The experimental results reveal that the active sites are the surface terminations of the hexagonal-tungsten line defect, where the in-plane-neighboring W atoms can break the C–O bonds inside the *COOH intermediates, thereby promoting the desorption of CO gas.