Uncovering Self-Optimization of Single-Atom Alloy for Active CO₂ Electrochemical Reduction Reaction

Renewable electricity-driven CO evolution from CO₂ offers a promising route for sustainable chemical production. Single-atom alloy (SAA) catalysts are emerging as promising candidates for electrochemical CO₂ reduction. However, the dynamic nature of SAAs within their local microenvironment often complicates our understanding of the underlying mechanisms that contribute to their enhanced performance. In this study, we introduce a single-atom Co-modified Au nanoparticle catalyst (Co₁O_x@Au) for the electrocatalytic reduction of CO₂ to CO. Using operando X-ray absorption spectroscopy (XAS), we observe the dynamic transformation of Co₁O_x@Au into a low-valence Co₁Au SAA, driven by the applied voltages. This behavior strengthens the atomic interaction between Au and Co, thus ensuring a reinforced adsorption of the crucial *COOH intermediate, which is corroborated by operando synchrotron-radiation Fourier transform infrared spectroscopy (SR-FTIR). Furthermore, the strengthened Au-Co interaction facilitates the subsequent desorption of the *CO intermediate, allowing for efficient CO formation and release. These insights highlight the self-optimization behavior of SAAs towards improving CO₂ reduction selectivity.