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

Powered by renewable electricity, electrochemical CO 2 reduction (CO 2 R) 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 CO 2 -to-C 2+ 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 CO 2 R selectivity and activity in a three-electrode electrochemical cell. The wrinkled electrode structure significantly increases the electrochemical active surface area, resulting in enhanced CO 2 R 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 (V RHE ), and a 50% increase in partial current density for C 2+ products for a wrinkled copper electrode at -1.05 V RHE compared to a planar copper electrode. A wrinkled gold-copper tandem electrode further enhances the partial current density of C 2+ products by an additional 60% beyond that of the wrinkled copper electrode (at -1.05 V RHE ), illustrating the synergistic effect of the three-dimensional wrinkled morphology combined with tandem catalysis. Tafel plot analysis revealed effective mass transport for C 2+ 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 CO 2 to desired fuels and chemicals. • Wrinkling increases the electrochemical active surface area by at least 5 times • Local production of *CO enhances C 2+ product formation compared to pure copper • Wrinkled tandem catalyst showed 60% higher C 2+ partial current density. • Wrinkled tandem catalyst enabled effective mass transport for C 2+ product generation