Direct H₂O₂ Synthesis, without H₂ Gas

We report here the direct hydrogenation of O₂ gas to form hydrogen peroxide (H₂O₂) using a membrane reactor without H₂ gas. Hydrogen is sourced from water, and the reactor is driven by electricity. Hydrogenation chemistry is achieved using a hydrogen-permeable Pd foil that separates an electrolysis chamber that generates reactive H atoms, from a hydrogenation chamber where H atoms react with O₂ to form H₂O₂. Our results show that the concentration of H₂O₂ can be increased ∼8 times (from 56.5 to 443 mg/L) by optimizing the ratio of methanol-to-water in the chemical chamber, and through catalyst design. We demonstrate that the concentration of H₂O₂ is acutely sensitive to the H₂O₂ decomposition rate. This decomposition rate can be minimized by using AuPd alloy catalysts instead of pure Pd. This study presents a new pathway to directly synthesize H₂O₂ using water electrolysis without ever using H₂ gas.