Solar‐Driven Production of Hydrogen Peroxide from Water and Dioxygen

Hydrogen peroxide, which is a green oxidant and fuel, is produced by a two‐electron/two‐proton reduction of dioxygen, two‐electron/two‐proton oxidation of water, or a combination of four‐electron/four‐proton or/and two‐electron/two‐proton oxidation of water and two‐electron/two‐proton reduction of dioxygen. There are many reports on electrocatalysts for selective two‐electron/two‐proton reduction of dioxygen to produce hydrogen peroxide instead of four‐electron/four‐proton reduction of dioxygen to produce water. As compared with the two‐electron/two‐proton reduction of dioxygen to produce hydrogen peroxide, fewer catalysts are known for the selective two‐electron/two‐proton oxidation of water to produce hydrogen peroxide instead of four‐electron/four‐proton oxidation of water to evolve dioxygen. Thus, solar‐driven production of hydrogen peroxide mainly consists of the catalytic four‐electron/four‐proton oxidation of water and the catalytic two‐electron/two‐proton reduction of dioxygen. The overall reaction is the solar‐driven oxidation of water by dioxygen to produce hydrogen peroxide. Either or both the four‐electron/four‐proton or/and the two‐electron/two‐proton oxidation of water and the two‐electron/two‐proton reduction of dioxygen requires photocatalysts. The yield of hydrogen peroxide is improved when the compartment for the photocatalytic four‐electron/four‐proton or/and two‐electron/two‐proton oxidation of water is separated from that for the catalytic two‐electron/two‐proton reduction of dioxygen using a two‐compartment cell separated by a membrane. The overall solar‐driven oxidation of water by dioxygen, which is the greenest oxidant, to produce hydrogen peroxide can be combined with catalytic oxidation of various substrates by hydrogen peroxide Sunny side up! This review focuses on the solar‐driven production of hydrogen peroxide by means of two‐electron/two‐proton or/and four‐electron/four‐proton oxidation of water and two‐electron/two‐proton reduction of dioxygen.