Positioning Cu in Templated Porous Ag for Active and Selective Electroreduction to C2+ Products

Abstract

Combining Cu with CO-producing Ag is a promising strategy to improve the selectivity of a CO2 reduction catalyst. However, the influence of the spatial distribution of the two metals is challenging to investigate. A synthesis route to deposit Cu either on top of a templated porous Ag electrode using sputter coating or inside the porous Ag structure using electrodeposition is presented. The Cu location is confirmed using advanced microscopy images, showing that for the electrodes with electrodeposited Cu, the interfacial area between Cu and Ag is higher. Catalytic testing demonstrates increased C2+ production, a lower H2 selectivity, and higher ethanol-to-ethylene ratio for all bimetallic electrodes than for monometallic Cu or Ag catalysts. This is possibly due to CO spillover from Ag to Cu, electronic interaction between the two metals, or a higher local pH inside the Ag pores. Despite a significant loss of Cu, a high production of ethylene and ethanol is maintained over 6 h of electrolysis. Thus, engineering porous bimetallic electrodes provides an effective strategy to improve the ethylene and ethanol activity and selectivity of Cu-based catalysts.