Nitrogen Defects in Porous Carbons with Adjacent Silver Nanoclusters for Efficient CO₂ Reduction

Abstract

Electrochemical CO 2 reduction is an environmentally sustainable way for CO 2 conversion and utilization, the development of which needs highly efficient catalysts. Ag-based materials are one kind of electrocatalyst that are catalytically active for CO 2 reduction to CO. In this work, Ag clusters were fabricated on nitrogen-doped porous carbon nanomaterials by a hightemperature annealing method. The well-dispersion of Ag sites on nitrogen-doped carbons (Ag/NC) promoted CO production. As a result, Ag/NC showed a maximum Faradaic efficiency of 94 % at À 0.7 V versus reversible hydrogen electrode (vs RHE) at room temperature. In addition, Ag/NC showed good CO 2 reduction stability, and the CO Faradaic efficiency remained stable at about 90 % at À 0.7 V vs RHE for 12 h. Density functional theory calculation indicated that the cooperation of Ag and N-dopings effectively reduced the activation energy barrier of CO 2 reduction relative to hydrogen evolution reaction and thus effectively promoted the electrocatalytic reduction of CO 2 molecules to CO. This method provides a new idea for the synthesis of CO 2 reduction catalysts with higher activity, selectivity and stability.