The site pair matching of a tandem Au/CuO-CuO nanocatalyst for promoting the selective electrolysis of CO 2 to C 2 products.

Tandem catalysis, in which a CO 2 -to-C 2 process is divided into a CO 2 -to-CO/*CO step and a CO/*CO-to-C 2 step, is promising for enhancing the C 2 product selectivity when using Cu-based electrochemical CO 2 reduction catalysts. In this work, a nanoporous hollow Au/CuO-CuO tandem catalyst was used for catalyzing the eCO 2 RR, which exhibited a C 2 product FE of 52.8% at -1.0 V vs. RHE and a C 2 product partial current density of 78.77 mA cm -2 at -1.5 V vs. RHE. In addition, the C 2 product FE stably remained at over 40% over a wide potential range, from -1.0 V to -1.5 V. This superior performance was attributed to good matching in terms of the optimal working potential and charge-transfer resistance between CO/*CO-production sites (Au/CuO) and CO/*CO-reduction sites (CuO). This site pair matching effect ensured sufficient supplies of CO/*CO and electrons at CuO sites at the working potentials, thus dramatically enhancing the formation rate of C 2 products.