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 CO-generating catalyst on the confined OD-Cu surface. Our research presents a strategy for constructing a productive tandem structure for the CO₂RR.