Scalable synthesis of Cu(-Ag) oxide clusters via spark ablation for the highly selective electrochemical conversion of CO2 to acetaldehyde

Abstract The electrochemical conversion of CO2 into the base chemical acetaldehyde offers a sustainable and green alternative to the Wacker process. However, current electrocatalysts cannot effectively compete with heterogeneous processes due to their limited selectivity towards acetaldehyde, resulting in low energy efficiencies. Herein, we report a theory-guided synthesis of a series of Cu(-Ag) oxide cluster catalysts (~ 1.5 nm) immobilized on various hetero-atom doped carbonaceous supports, produced via spark ablation of Cu (and Ag) electrodes. These catalysts achieved an impressive acetaldehyde selectivity of up to 92% at only 600 mV from the equilibrium potential. Further, the catalyst exhibited exceptional catalytic stability during a rigorous 30-hour stress test involving 3 repeated start-stop cycles. In situ X-ray absorption spectroscopy showed that the initial oxide clusters were completely reduced under cathodic potential and maintained their metallic nature even after exposure to air, explaining the stable performance of the catalyst. First-principles simulations further elucidated the possible mechanism of CO2 conversion to acetaldehyde.