A Mechanistic Approach to Enhance and Better Understand the Carbon Dioxide Reduction Reaction

While the carbon dioxide reduction reaction (CO2RR) is a promising approach to the synthesis of value-added chemical conversion, much is left unknown regarding the kinetic and mass transport mechanisms which govern product selectivity and overall reaction rate. This study investigated Ni- and Cu-based catalysts largely derived from ZIF-8 precursors with the aim of generating products with high partial current densities and faradaic efficiencies. A particular focus was put on tandem electrocatalysis, where Cu-based active sites were synthesized in the presence of Ni-N-C to achieve multi-carbon products in increased quantities. Both H-cell and rotating disk electrode (RDE) voltammetry experiments were employed to determine the mechanistic tendencies and limitations for several catalysts showing high selectivity for individual CO2RR products. Results have indicated the tunability of several catalysts towards the production of syngas with varying ratios of CO and H2. The kinetic characteristics and tendencies of tandem electrocatalysts are also inferred through the variation of active site loading and proximity, as well as the use of electrode rotation during electrochemical measurements.