In Situ Fabrication and Reactivation of Highly Selective and Stable Ag Catalysts for Electrochemical CO₂ Conversion

In this work, the highly selective and stable electrocatalytic reduction of CO₂ to CO on nanostructured Ag electrocatalysts is presented. The Ag electrocatalysts are synthesized by the electroreduction of Ag₂CO₃ formed by in situ anodic-etching of Ag foil in a KHCO₃ electrolyte. After 3 min of this etching treatment, the Ag₂CO₃-derived nanostructured Ag electrocatalysts are capable of producing CO with up to 92% Faradaic efficiency at an overpotential as low as 290 mV, which surpasses all of the reported Ag catalysts at identical conditions to date. In addition, the anodic-etched Ag retained ∼90% catalytic selectivity in the electroreduction of CO₂ to CO for more than 100 h. The Ag₂CO₃-derived Ag is able to facilitate the activation of CO₂ via reduction of the activation energy barrier of the initial electron transfer and provide an increased number of active sites, resulting in the dramatically improved catalytic activity for the reduction of CO₂ to CO.