Metal–oxygen hybridization in Agcluster/TiO2 for selective CO2 photoreduction to CH4

•Strong metal–oxygen hybridization was successfully incorporated in Agcluster/TiO2.•Agcluster/TiO2 shows a high photocatalytic CH4 generation activity and selectivity.•Ag–O hybridization effectively optimizes photogenerated carrier dynamics.•Ag–O hybridization promotes the multiple-proton–electron coupling transfer process. Selective photocatalytic reduction of CO2 to CH4 is one of the most efficient ways to achieve carbon neutralization. However, the formation of methane remains a challenge due to the slow multiple-proton-coupled electron transfer process and the involvement of various C1 intermediates. Herein, an Agcluster/TiO2 catalyst with Ag-O hybridization was synthesized by supporting Ag clusters on anatase phase TiO2 microspheres for photocatalytic CO2 methanation. The Agcluster/TiO2 sample presents an electron selectivity of 86 % for CH4 production with a yield of 25.25 μmol g–1 h−1. Mechanistic study reveals that Ag clusters accelerate the separation and migration of photogenerated carriers, and enhance the adsorption of CO2. Moreover, the Ag-O hybridization promotes the multiple-proton–electron coupling transfer process by effectively stabilizing intermediates and facilitating *CO hydrogenation to *CHO, resulting in selective CO2 reduction to CH4. This work provides a new insight into the development of selective photocatalytic conversion of CO2 to methane by constructing supported cluster catalysts.