Unlocking Multi-Product Selectivity in Olefin Electro-oxidation through Cooperative Cation/Oxygen Species Modulation

The selective oxidation of olefins is a cornerstone reaction in industry, as it directly creates high-value oxygen-containing building blocks for producing plastics, fine chemicals, and pharmaceuticals. A strong stoichiometric oxidant is often demanded to tailor the selectivity, while using electrons as clean reagents in electrochemical oxidation offers a promising alternative but lacks the guiding principle and tuning strategy toward each product. Herein, we developed an electrochemical olefin oxidation strategy of concerted oxygen species and cation tuning to achieve highly selective oxidation of olefins into three products of vicinal diol, aldehyde, and epoxide, all with selectivities >90%. Through systematic mechanistic analysis, we revealed that hydrophilic Li⁺ ions stabilize *OH intermediates from H₂O oxidation on dimensionally stable anodes (DSAs), promoting its coupling with olefin radicals to yield vicinal diols; hydrophobic tetraethylammonium cations enrich O₂ at the anode interface, steering olefins toward a C═C cleavage pathway toward aldehyde formation; tetrabutylammonium cations facilitate cathodic O₂ reduction into an ^•OOH radical that couples with a sacrificial Ti anode toward selective epoxide production. This work not only provides a prospective pathway for green and efficient olefin oxidation that eliminates strong stoichiometric oxidants but also emphasizes the oxygen species/cations co-tuning method for optimizing electrochemical oxidation properties.