Gold Self-Assembly on Copper Electrodes Promotes n-Propanol Formation in Electrochemical CO₂ Reduction

The electrochemical CO₂ reduction reaction (CO₂RR) offers a promising route to mitigate greenhouse gas emissions by converting CO₂ 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 Au³⁺-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 CO₂RR electrocatalysts.