Promoting Photocatalytic CO2 Methanation by the Construction of Cooperative Copper Dual-Active Sites

Selective photocatalytic CO2 methanation provides an attractive avenue to address energy and environmental issues. However, impediments such as the sluggish adsorption and activation of CO2 and H2O molecules, along with unexpected intermediate desorption, greatly restrict the activity and selectivity of photocatalytic CO2 methanation. To address these issues, we devised a dual-active site catalyst comprising Cu single atoms (SAs) and nanoclusters (NCs) supported on defective TiO2 (Cu1+NCs/BT). As a result, a remarkable CH4 selectivity of 98% with a yield of 19.63 μmol gcat.–1 h–1 can be obtained over the as-prepared Cu1+NCs/BT in pure water. Mechanistic studies reveal the enhanced performance could be ascribed to the synergistic effect of the Cu dual-active sites, where Cu SAs adsorb and activate CO2, while Cu NCs boost H2O adsorption and dissociation for *H coverage. Additionally, the adjacent Cu dual-active site could jointly stabilize the *CO intermediate and reduce the energy barrier for *CO protonation, promoting the multielectron transfer process.