Preparation of a silver electrode with a three-dimensional surface and its performance in the electrochemical reduction of carbon dioxide

An Ag electrode was surface-modified by ozonation and subsequent electroreduction. The modified electrode was more active and selective than its smooth-surfaced counterpart in reducing CO2 to CO. Surface modification facilitated the formation of a three-dimensional structure on the Ag surface, thereby enlarging the number of reactive species available for CO2 electroreduction. Moreover, the modified Ag electrode retained durable activity using potentiostatic pulse electrolysis. The main carbon-containing substances produced were large amounts of CO accompanied with relatively low quantities of formic acid, methanol, methane and formaldehyde. On the basis of Tafel plots and the addition of known products, it is proposed that the electroreduction of CO2 on the Ag electrode proceeds via a mechanism involving generation of CO and HCOOH. The Ag electrode deactivation was caused by CHOads and/or COHads absorbed species on the Ag surface. (C) 2016 Elsevier Ltd. All rights reserved.