Electrocatalysis for CO2 Reduction: Controlling Selectivity to Oxygenates and Multicarbon Products

Abstract

Many technical challenges remain for the implementation of CO2 electrolysis as a practical means for CO2 utilization. Here, we outline strategies for improving the performance of catalysts for the electroreduction of CO2 to oxygenated and multicarbon reduction products. To this end, we will first discuss how engineering the surface structure of Cu electrocatalysts led to the discovery of active site structure-selectivity relationships. Using a combination of electrocatalysis experiments and in situ surface probe microscopy, we demonstrate that undercoordinated sites are selective motifs for oxygenates and C-C coupling. By comparing these results with state-of-the-art Cu electrocatalysts from the literature, we show that different morphologies have similar intrinsic activities for CO2 reduction. Afterwards, we will discuss a tandem catalysis approach for improving upon these normalized CO2 reduction activities, which is enabled by utilizing bimetallic electrodes consisting of Au nanoparticles on polycrystalline Cu (Au/Cu). At low overpotentials, the Au/Cu electrocatalyst has a synergistic catalytic activity superior to that of either Cu or Au, indicating that tandem catalysis mechanisms can be utilized to increase the energy efficiency for alcohol production. By comparing Au/Cu to Cu, we highlight common potential-driven trends in the selectivity to oxygenated and multicarbon products, providing insights on how to develop new electrocatalysts that can guide selectivity to valuable chemicals and fuels.