A Highly Porous Copper Electrocatalyst for Carbon Dioxide Reduction

Abstract Electrochemical reduction of carbon dioxide (CO 2 ) is an appealing approach toward tackling climate change associated with atmospheric CO 2 emissions. This approach uses CO 2 as the carbon feedstock to produce value‐added chemicals, resulting in a carbon‐neutral (or even carbon‐negative) process for chemical production. Many efforts have been devoted to the development of CO 2 electrolysis devices that can be operated at industrially relevant rates; however, limited progress has been made, especially for valuable C 2+ products. Herein, a nanoporous copper CO 2 reduction catalyst is synthesized and integrated into a microfluidic CO 2 flow cell electrolyzer. The CO 2 electrolyzer exhibits a current density of 653 mA cm −2 with a C 2+ product selectivity of ≈62% at an applied potential of −0.67 V (vs reversible hydrogen electrode). The highly porous electrode structure facilitates rapid gas transport across the electrode–electrolyte interface at high current densities. Further investigations on electrolyte effects reveal that the surface pH value is substantially different from the pH of bulk electrolyte, especially for nonbuffering near‐neutral electrolytes when operating at high currents.