Mechanistic Study of CO2 Reduction in a Metal Nanoparticle/Ligand-Based Nanoconfined Pocket

Abstract

Electrochemically reducing CO2 holds promise for producing value-added chemicals. Achieving this requires electrocatalysts with high selectivity and energy efficiency. Nanopocket engineering enhances catalytic activity by modulating interfacial reactivity and stabilizing key intermediates, especially those involved in the rate-determining step. Here, we use density functional theory to systematically evaluate the CO2 reduction reaction (CO2RR) and the competing hydrogen evolution reaction (HER) on three systems: Ag surface without confinement, double Ag confinement, and Ag surface confined by a ligand in the absence and presence of interfacial water. We find that decreasing the confinement distance from 7 to 4 Å stabilizes CO2RR intermediates over HER in the double Ag and Ag/ligand systems, due to additional secondary interactions, such as hydrogen bonding, in the latter. The hydrogen bonding network is further enhanced in the presence of interfacial water, resulting in increased *COOH stabilization over *H in Ag/ligand and double Ag systems at a 7 Å confinement distance. The increased stabilization of *COOH over *H can be attributed to the high selectivity and activity for CO2RR in Ag/ligand catalysts. These results systematically reveal how nanoconfinement can be an effective strategy for controlling reactivity at the gas–liquid–solid interfaces toward highly selective CO2RR.