Mechanistic investigation on Ag-Cu2O in electrocatalytic CO2 to CH4 by in situ/operando spectroscopic and theoretical analysis

Abstract

Silver-copper electrocatalysts have demonstrated effectively catalytic performance in electroreduction CO2 toward CH4, yet a revealing insight into the reaction pathway and mechanism has remained elusive. Herein, we construct chemically bonded Ag-Cu2O boundaries, in which the complete reduction of Cu2O to Cu has been strongly impeded owing to the presence of surface Ag shell. The interfacial confinement effect helps to maintain Cu+ sites at the Ag-Cu2O boundaries. Using in situ/operando spectroscopy and theoretical simulations, it is revealed that CO2 is enriched at the Ag-Cu2O boundaries due to the enhanced physisorption and chemisorption to CO2, activating CO2 to form the stable intermediate *CO. The boundaries between Ag shell and the Cu2O mediate local *CO coverage and promote *CHO intermediate formation, consequently facilitating CO2-to-CH4 conversion. This work not only reveals the structure-activity relationships but also offers insights into the reaction mechanism on Ag-Cu catalysts for efficient electrocatalytic CO2 reduction.