Gold Self‐Assembly on Copper Electrodes Promotes n‐Propanol Formation in Electrochemical CO ₂ Reduction

Abstract The electrochemical CO 2 reduction reaction (CO 2 RR) offers a promising route to mitigate greenhouse gas emissions by converting CO 2 into valuable chemicals. Among multi‐carbon products, n‐propanol is particularly appealing due to its high energy density (~27 MJ/L) and broad industrial applications. However, achieving high selectivity for n‐propanol remains a formidable challenge, requiring catalysts capable of facilitating complex reaction pathways and avoiding competing side reactions. In this study, we present a Cu/Cys/Au catalyst architecture that is prepared through a self‐assembled monolayer (SAM) that significantly enhances the Faradaic efficiency for n‐propanol production. Specifically, Cu substrates are modified with cysteamine SAMs to uniformly anchor a Au 3+ ‐dimercaptosuccinate complex, which enable uniform Au electrodeposition. The resulting Cu/Cys/Au electrode achieves a Faradaic efficiency of 29.1 % for n‐propanol at −1.2 V vs. RHE, representing a significant improvement over conventional Au−Cu electrocatalysts. Control studies reveal the necessity of both Au and Cu for selective n‐propanol formation, while mixed SAMs with varying cysteamine and propanethiol ratios allow for precise tuning of Au coverage on Cu. These findings underscore the potential of SAM‐based strategies for precise surface engineering, offering a pathway for selective CO 2 RR electrocatalysts.