Selective and Scalable Aldehyde Production via Partial Oxidation of Alcohols in Acidic Media

While challenging, scalable partial electro-oxidation of alcohols to aldehydes presents a sustainable pathway for producing value-added chemicals along with green hydrogen. Here, we first pinpoint the optimal electrolyte environment for selective partial oxidation of alcohols, <i>i.e.</i>, acidic media, and then develop a CoO-Co₃O₄ catalyst integrated into an asymmetric proton-exchange membrane electrolyzer, enabling selective and stable alcohol partial oxidation. Furthermore, separation of the pure alcohol anolyte from the aqueous catholyte minimizes competing oxygen evolution and mitigates metal dissolution. Detailed mechanistic investigations reveal that the CoO/Co₃O₄ interface promotes the rate-limiting first proton-coupled electron transfer step, enabling >95% aldehyde selectivity and >90% Faradaic efficiency for a broad scope of alcohols. Encouragingly, the system maintains high selectivity (>90%) toward aldehyde over other overoxidized products, even at industrially relevant current densities up to 200 mA cm^-2, highlighting a promising improvement over the conventional aqueous system. Overall, this strategy provides an effective platform for selective alcohol oxidation and offers a promising path toward scalable electrosynthetic technology.