Mechanistic Insights into the Electrochemical Reduction of CO2 to CO on Nanostructured Ag Surfaces

Electroreduction of CO2 in a highly selective and efficient manner is a crucial step toward CO2 utilization. Nanostructured Ag catalysts have been found to be effective candidates for CO2 to CO conversion. In this report, we combine experimental and computational efforts to explore the electrocatalytic reaction mechanism of CO2 reduction on nanostructured Ag catalyst surfaces in an aqueous electrolyte. In contrast to bulk Ag catalysts, both nanoparticle and nanoporous Ag catalysts show enhanced ability to reduce the activation energy of the CO2 to COOHads intermediate step through the low-coordinated Ag surface atoms, resulting in a reaction mechanism involving a fast first electron and proton transfer followed by a slow second proton transfer as the rate-limiting step.