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

Abstract

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 <i>operando</i> 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 CH_<i>x</i>. This work presents a highly efficient strategy for high-performance CO₂ methanation via well-defined metal cluster catalysts.