Photodriven Catalytic Hydrogenation of CO2 to CH4 with Nearly 100% Selectivity over Ag25 Clusters

The conversion of chemically inert carbon dioxide and its photoreduction to value-added products have attracted enormous attention as an intriguing prospect for utilizing the principal greenhouse gas CO2. Herein, we explore the use of Ag25 clusters with well-defined atomic structures for high-selectivity photocatalytic hydrogenation of CO2 to methane. Ag25 clusters, with molecular-like properties and surface plasmon resonance, exhibit competitive catalytic activity for light-driven CO2 reduction that yield an almost 100% product selectivity of methane at a relatively mild temperature (100 °C). DFT calculations reveal that the absorption of CO2 on Ag25 clusters is energetically favorable. The methanation of the Ag25 cluster catalyst has been investigated by operando infrared spectroscopy, verifying that methane was produced through a -H-assisted multielectron reaction pathway via the transformation of formyl and formaldehyde species to form surface CHx. This work presents a highly efficient strategy for high-performance CO2 methanation via well-defined metal cluster catalysts.