Delicate control of a gold-copper oxide tandem structure enables the efficient production of high-value chemicals by electrochemical carbon dioxide reduction

The electrochemical carbon dioxide reduction reaction (CO2RR) has substantial potential for carbon capture and utilization (CCU), aiming to produce carbon-neutral fuels and valuable chemical feedstocks. Copper (Cu) is recognized as the primary metal catalyst capable of facilitating C-C coupling and producing multi-carbon compounds. The tandem catalyst approach, particularly the oxide-derived Cu (OD-Cu)-based tandem catalyst, has been reported to improve the selectivity for multicarbon compounds such as ethylene and ethanol. However, the impact of the loading structure of the CO-producing catalyst in the tandem catalyst on CO2RR performance has not been thoroughly investigated. In this study, we developed Au nanoparticles with different sizes and loading densities on Cu2O and investigated their CO2RR properties. Tandem catalysts featuring smaller Au nanoparticles exhibited increased activity in the electrochemical CO2RR, resulting in an anodic shift in the potential. Improved Faradaic efficiencies (FEs) and partial current densities (PCDs) of C2+ were also observed for tandem catalysts with smaller Au nanoparticles. Remarkably, the FE and PCD of n-propanol increased as the coverage of Au nanoparticles increased, in contrast to those of C2 products such as ethylene and ethanol. The effectiveness of the tandem effect depends on the increase in local CO concentration facilitated by the COgenerating catalyst on the confined OD-Cu surface. Our research presents a strategy for constructing a productive tandem structure for the CO2RR.