Roughness Effect of Cu on Electrocatalytic CO 2 Reduction towards C 2 H 4 .

Electrochemical reduction of CO 2 to produce valuable multi-carbon products is a promising avenue for promoting CO 2 conversion and achieving renewable energy storage, and it has also attracted considerable attention recently. However, the synthesis of Cu electrode with a controllable electrochemical active surface area (ECSA) to understand its role in CO 2 reduction to C 2 H 4 remains challenging. Herein, a series of Cu electrodes with different ECSA is synthesized through a simple oxidation-reduction approach. We reveal that the improved selectivity of C 2 H 4 is proportional to the ECSA of Cu in the low ECSA range, and a further increase in ECSA has a negligible effect on its selectivity. The enlarged surface area could strengthen the local pH effect near the surface of Cu electrode and suppress the generation of C 1 products as well as H 2 . The study provides a feasible strategy to rationally design electrocatalysts with high electrochemical CO 2 reduction performances.