Tandem Electrodes for Carbon Dioxide Reduction into C2+ Products at Simultaneously High Production Efficiency and Rate

Electrochemical reduction of CO2 to multi-carbon chemicals over Cu-derived catalysts is currently restricted by the low faradaic efficiency (FE) and production rate of C2+ products. Here, we report tandem gas diffusion electrodes yielding C2+ products at simultaneously high FE and production rate via sequential CO2 reduction on two independent, selective, and adjacent catalyst layers. The tandem electrodes possess the intrinsic benefits of lower onset potential and higher partial current densities of C2+ products compared to bare copper electrodes. Through balancing the CO generation and consumption rates, the FEs of both C2+ products and C2H4 for tandem electrodes can be maximized to exceed those for bare copper electrodes. The optimized Cu/Ni-N-C tandem electrode, which comprises sequential Cu and Ni-N-C catalyst layers, reaches FE of 62% and partial current density of 415 mA cm(-2) for C2H4 at -0.70 V versus RHE.