Direct H 2 O 2 Synthesis, without H 2 Gas.

We report here the direct hydrogenation of O 2 gas to form hydrogen peroxide (H 2 O 2 ) using a membrane reactor without H 2 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 O 2 to form H 2 O 2 . Our results show that the concentration of H 2 O 2 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 H 2 O 2 is acutely sensitive to the H 2 O 2 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 H 2 O 2 using water electrolysis without ever using H 2 gas.