Ligand-induced surface modification of cuprous oxide improves C2+ product selectivity in electrochemical CO2 reduction

This study explores the surface modification of Cu2O cubes by the integration of a thin layer of Cu-metal-organic framework (Cu-MOF, bridging ligand = benzene dicarboxylic acid) to form Cu2O@Cu-MOF core-shell structure for the improved electrochemical CO2 reduction reaction (CO2RR) and selectivity towards C2+ products. The Cu-MOF layer helps to stabilize both Cu+ and Cu2+ species and optimizes the charge transfer through the interface of Cu-MOF and Cu2O to improve the activity and selectivity. The surface modification enhances the adsorption of CO2 and increases active sites to improve the electrocatalytic activity. The core-shell structure promotes the selective production of C-2 and C2+ products compared to that of Cu2O. Under the optimized conditions, Cu2O@Cu-MOF produced Faradaic efficiency (FE) of 30.5 % and 7.5 % for the C-2 products and n-propanol, respectively-far better than that of Cu2O (12 % C-2 products only). Cu2O@Cu-MOF achieved an FE(C1 and C2+) of 61.9 % with a major production of oxygenated products (FE = 54 %). Further, Cu2O@Cu-MOF attained an FE(C1 and C2+) of 83 % with FEC2+ = 42.4 % in flow-cell, far better than the H-cell results.