Single-atom mediated crystal facet engineering for the exceptional production of acetate in CO electrolysis†

The production of value-added liquid fuels via the electroreduction of CO has received widespread attention. Although copper (Cu) has demonstrated promising activity in producing multi-carbon products, the yield of a specific product like acetate remains limited, resulting in low resource utilization efficiency. Here, we present a Co single-atom mediated Cu(111) (CuCo₁) triangular sheet, in which the Co single atom was specifically modified on the exposed Cu(111) crystal face. Importantly, CuCo₁ sheets achieve an exceptional acetate faradaic efficiency of 72% at a high current density of 600 mA cm⁻², along with the topmost acetate formation rate of 1.11 μmol s⁻¹ cm⁻², surpassing most state-of-the-art Cu-type catalysts. Moreover, the CuCo₁-based membrane electrode assembly (MEA) enables a stable production of acetate at 600 mA cm⁻² for over 500 h, demonstrating the exceptional stability of CuCo₁. In situ spectroscopic and computational investigations suggest that Co single atoms can significantly modulate the CO activation step to form *CO adsorption on both the top and bridge sites of Cu sheets, triggering asymmetric C–C coupling to facilitate the *OCCOH intermediate. Furthermore, a Co single atom reduces the energy barrier for the second hydrogenation step over Cu(111), thereby stabilizing ethenone production and enhancing acetate yield. This work provides an avenue to design highly efficient and stable Cu catalysts via the combination of crystal facet design and a single atom promoter.