Direct conversion of water to hydrogen peroxide on single electrode towards partial oxidation of propylene

We report an approach of direct production of H2O2 from water by applying altering potential in the electrocatalysis. By switching potentials periodically between positive to negative, oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) occurs sequentially on a single electrode loaded catalysts, which leads to the reduction of the newly-formed OER active species, forming H2O2 directly. The H2O2 production is dependent on the time and potentials of OER and ORR, which is optimized in this study. Besides, a waiting time is set after each period to let H2O2 diffusion from the catalyst surface. Different catalysts are employed to test the feasibility of this approach, including glassy carbon, graphene oxide, nickel particles, nickel foam, and palladium particles. All these catalysts result in the production of H2O2 at various reaction rates. Ni offers the highest H2O2 productivity. With the prolonging of the reaction time, the decomposition of H2O2 occurs on the surface of Ni catalysts, which is inhibited by the addition of Zn into the catalysts. The in-situ generated H2O2 is used for partial oxidation of propylene by passing propylene into the porous electrode during the reaction, which lead to the formation of dimethyl ether and adipic acid. This study shows a new route of the direct synthesis and utilization of H2O2 for the generation of valuable chemicals.