Controlling the C 1 /C 2+ product selectivity of electrochemical CO 2 reduction upon tuning bimetallic CuIn electrocatalyst composition and operating conditions.

Electrochemical carbon dioxide (CO 2 ) reduction (eCO 2 R) over Cu-based bimetallic catalysts is a promising technique for converting CO 2 into value-added multi-carbon products, such as fuels, chemicals, and materials. For improving the process efficiency, electrocatalyst development for the eCO 2 R must be integrated with tuning of operating conditions. For example, CuIn-based materials typically lead to preferential C 1 product selectivity, which delivers the desired C 2+ products upon varying the In/Cu ratio and operating conditions ( i.e. , in 0.1 M KHCO 3 electrolytes using an H-type cell with a cation exchange membrane vs. in 1 M KOH electrolytes using a flow cell with an anion exchange membrane). At lower Cu-loading ( i.e. , InCu 5 O x material), the maximum faradaic efficiency of HCOOH (FE HCOOH ) of 70% was achieved at -1 V versus the reversible hydrogen electrode ( vs. RHE) in an H-type cell. However, upon increasing the Cu loading, the preferential product selectivity could be altered: the InCu 73 O x material led to a high CO selectivity (maximum FE of 51%) in the H-type cell at -0.8 V vs. RHE and delivered a current density of 100 mA cm -2 with a FE C2+ of up to 37% at -0.8 V vs. RHE in the flow cell configuration. Various characterization tools were also employed to probe the catalytic materials to rationalize the electrocatalytic performance.