Tunable Charge Transfer for Electrocatalytic CO2 Reduction on Ag2CO3-Derived Nanostructured Ag

The electrochemical reduction of CO2 on nanostructured Ag catalysts with different thickness was systematically evaluated in this work. The nanostructured Ag catalysts were prepared via a rapid two-step synthesis: anodic formation of Ag₂CO₃ on Ag foil, followed by in-situ electrochemical reduction to nanoporous metallic Ag. By this simple and fast fabrication method, nanoporous Ag catalysts with different thicknesses were controllably synthesized. We show that a gradually enhanced catalytic selectivity and activity for the reduction of CO2 to CO can be achieved at low overpotenials (290 mV) upon increasing the thickness of nanoporous Ag. Additionally, the overpotentials required for achieving ~90 % Faradaic Efficiency for the conversion of CO2 into CO gradually decreased with an increase in the thickness of nanoporous Ag. Further analysis indicates that the increased catalytic selectivity and activity for electroreduction of CO2 to CO at reduced overpotentials on the thicker nanoporous Ag is unlikely to be correlated with local pH effect, but the facile charge transfer for CO2 reduction to CO by lowering the activation energy barrier.