Effects of Synthesized Silver Nanoplate Structures on the Electrochemical Reduction of CO₂.

Abstract Using a tunable electroless nanoplating reaction, different silver structures were synthesized, characterized, and tested as catalysts to improve the electrochemical reduction of CO2 towards CO and its byproducts hydrogen and formate. Relative to a planar polycrystalline silver surface, the faradaic efficiency to CO was significantly improved, from 7% to 67% at -0.6 V vs. a rotating hydrogen electrode (RHE) and from 51% to 97% at -1.0 V vs. RHE, decreasing the parasitic evolution of hydrogen and formate. By comparing the catalytic performance of three intensively characterized silver structure types, namely high aspect ratio nanoplates, particulate nanoplate clusters, and interconnected grain-like particles, in-depth insights into various effects that influence the observed reactions are presented. In particular, at low potentials and high current densities, the catalytic performance is more related to the electrochemical surface area and local transport effects. The obtained results demonstrate the relevance of structural control in electrocatalysts and the special effects of nanoplate structures. Thus, our findings provide a useful groundwork for the practical design of electrocatalysts for CO2 reduction.