Tandem gold/copper catalysis and morphological tuning via wrinkling to boost CO2 electroreduction into C2+ products

Powered by renewable electricity, electrochemical CO2 reduction (CO2R) offers a sustainable route for the production of fuels and chemicals that are traditionally produced from fossil fuels. However, designing and developing an efficient electrocatalyst for CO2-to-C2+ product conversion remains challenging. Here, a gold-copper tandem catalyst electrode design is introduced that leverages the structural effects of a wrinkled morphology to improve the CO2R selectivity and activity in a three-electrode electrochemical cell. The wrinkled electrode structure significantly increases the electrochemical active surface area, resulting in enhanced CO2R current density for both the singular wrinkled gold and wrinkled copper electrodes. Specifically, there is a 130 % increase in partial current density towards CO for a wrinkled gold electrode versus planar gold electrode at −0.7 V versus the reversible hydrogen electrode (VRHE), and a 50 % increase in partial current density for C2+ products for a wrinkled copper electrode at −1.05 VRHE compared to a planar copper electrode. A wrinkled gold-copper tandem electrode further enhances the partial current density of C2+ products by an additional 60 % beyond that of the wrinkled copper electrode (at −1.05 VRHE), illustrating the synergistic effect of the three-dimensional wrinkled morphology combined with tandem catalysis. Tafel plot analysis revealed effective mass transport for C2+ product generation on the optimized wrinkled gold-copper tandem electrode, attributed to the local *CO production by the tandem catalyst, facilitating enhanced C-C coupling on the copper catalyst compared to a purely copper based electrode. Experimental results show that the design and manipulation of the morphology of the tandem catalyst electrode achieved via step-by-step optimization can significantly enhance the selectivity and activity of the catalyst in converting CO2 to desired fuels and chemicals.