Bimetallic Cu-In hybrid electrocatalysts are promising noble metal-free catalysts for selective electrochemical CO₂ reduction reaction (ECO₂RR). Most reports show Cu-In catalysts are selective towards CO evolution. However, few show similarly high selectivity towards formate. Herein we fabricated composition tunable Cu-In hydroxides (Cu_xIn_y-OH) by the hydrothermal method and studied their composition effect on electrochemical CO₂ reduction in detail. We found that the selectivity of CO₂ reduction products shifted from CO to formate when the content of In increased in the Cu_xIn_y-OH electrocatalysts. The Cu rich electrocatalyst mostly produced CO, which could achieve a Faradaic efficiency (FE) to 75.8% at −0.59 V vs. RHE (Cu₇₆In₂₄ based electrocatalysts). In comparison, the In rich electrocatalysts selectively produced formate, which possessed the FE of formate up to 85% at −1.01 V vs. RHE. Our work systematically illustrates the composition effect on hybrid catalysts, and provides insights into the design of highly selective catalysts for ECO₂RR.

双金属Cu-In杂化电催化剂是用于选择性电化学CO ₂还原反应（ECO ₂ RR）的有前途的无贵金属催化剂。大多数报告显示 Cu-In 催化剂对 CO 析出具有选择性。然而，很少有人对甲酸盐表现出类似的高选择性。在此，我们通过水热法制备了成分可调的 Cu-In 氢氧化物（Cu _x In _y -OH），并详细研究了其成分对电化学 CO ₂还原的影响。我们发现当 Cu _x In _y中 In 含量增加时，CO ₂还原产物的选择性从 CO 转移到甲酸盐-OH 电催化剂。富铜电催化剂主要产生 CO，在 -0.59 V 与 RHE（基于Cu ₇₆ In ₂₄的电催化剂）下，其法拉第效率（FE）可达到 75.8% 。相比之下，富 In 电催化剂选择性地产生甲酸盐，在 -1.01 V 与 RHE 相比，甲酸盐的 FE 高达 85%。我们的工作系统地说明了混合催化剂的组成效应，并为 ECO ₂ RR的高选择性催化剂的设计提供了见解。