Suppressing hydrogen evolution for high selective CO₂ reduction through surface-reconstructed heterojunction photocatalyst

The utilization of solar energy for CO₂ reduction reaction (CO₂RR) into valuable hydrocarbons offers attractive solution towards low-carbon future, but their performance is affected by the competing hydrogen evolution reaction (HER) that occurs simultaneously. Herein, we proposed maximizing interface integration and surface reconstructing engineer strategy to improve the CO₂RR activity and selectivity of heterojunction photocatalyst. A surface-reconstructed ZnO/CuO_x catalysts are uniformly anchored on the porous carbon nanosheet arrays that are supported by carbon nanofibers (ZnO/CuO_x-C CNFs). Downsizing ZnO/CuO_x maximizes the interface integration of components to promote electron-hole pairs separation and increase surface active site density. Moreover, the surface reconstruction (the formation of the hydroxyl groups on ZnO via facile light irradiation) promotes the kinetic of CO₂RR to CH₄ and oxygen evolution reaction (OER), while depressing the competing HER and CO generation. All these advantages contribute to the excellent catalytic performance: a high CH₄ generation rate of 241.6 μmol h⁻¹ g⁻¹ with the selectivity of ∼96 % for ZnO/CuO_x-C CNFs under full light irradiation. The insight into the modification of photocatalyst structure and mechanism investigation pave the way for a new design strategy to advance solar photocatalytic technology for CO₂ reduction.