Bimetallic Cu‐In Catalysts for the Electroreduction of CO to C 2+ Products

ABSTRACT Copper‐based electrodes are widely used to catalyze the electrochemical reduction of CO 2 (CO 2 RR) and CO (CORR) to multi‐carbon (C 2 + ) products. Both processes suffer from poor selectivity, yielding a mixture of products such as ethylene, ethanol, propanol, and hydrogen. Alloying copper with a second metal offers a promising strategy to steer selectivity toward desired C─C coupled products. While Cu‐In catalysts have been studied for CO 2 RR, their performance in CORR remains largely unexplored. Herein, bimetallic Cu‐In catalysts with varying molar ratios were synthesized via a one‐step flame spray pyrolysis (FSP) method and compared to physical mixtures (PM) of Cu‐ and In‐oxides as reference samples. Under CORR conditions, the Cu‐only catalyst produced H 2 and C 2 + products, whereas the In‐only catalyst predominantly formed H 2 and acetate. Notably, the Cu 0.82 In 0.18 composition exhibited contrasting C 2 + selectivity: 30% for the FSP‐derived sample and 60% for the PM counterpart. In situ wide‐angle x‐ray scattering (WAXS) revealed that FSP‐prepared catalysts formed CuxIny alloys upon reduction, while PM samples retained separate phases of metallic Cu and In 2 O 3 . The isolated In 2 O 3 in PM samples appeared inactive in CORR, whereas the Cu x In y alloys in FSP‐prepared Cu 0.82 In 0.18 were detrimental to C‐C coupling, suggesting that alloy formation may suppress selectivity toward C 2 + products.