(682f) Highly Productive and Selective CO2-to-C2+ Conversion through in-Situ Spatial CO Management

Equally important to the development of catalysts for electrochemical CO₂ reduction, gas diffusion electrodes (GDEs) design plays a vital role in achieving the selectivity, productivity, and energy efficiency of a specific C₂₊ product at the level of industrial relevance simultaneously. Along the reaction pathway for C₂₊ products formation over Cu-based catalysts, a crucial step of C-C coupling through dimerization of adsorbed *CO or coupling of *CO with its hydrogenated derivatives (e.g., *CHO) has been identified by both experimental observation and theoretical calculation. This phenomenon provides an opportunity to design cascade reactions through CO intermediate to improve the yield of C₂₊ products. Some bimetallic tandem catalysts integrating Cu with a CO-generation metal (e.g., Ag and Au) have demonstrated the tandem catalysis effect, improving C-C coupling kinetics by increasing the partial pressure of CO (P_CO) near the Cu surface. However, when the tandem catalyst is applied in the conventional GDE comprising one homogeneous catalyst layer (CL), the CO utilization efficiency for C-C coupling is low. That is because the local CO concentration throughout the CL, analogous to that in a continuous stirred tank reactor, is relatively uniform but abruptly decreases to the lowest value. In this talk, distinguished from the tandem catalysts, we introduce tandem electrodes, where the temporal and spatial CO concentration profiles is in-situ managed, to enhance the utilization of CO and thus drive cascade CO₂-->CO-->C₂₊ conversion with a yield at an industrial scale. We demonstrated that segmented tandem electrodes, even incorporating the commercial Cu nanoparticles, could reach over 90% Faradaic efficiency (FE) of C₂₊ products (60% FE for C₂H₄) at a partial current density of above 1 A cm^-2. When a surface-modified Cu catalyst was used, the FE of C₂H₄ could be further increased to 70% at a partial current density of 1 A cm^-2.