Solar-Driven Generation of Hydrogen Peroxide on Phenol–Resorcinol–Formaldehyde Resin Photocatalysts

Photocatalytic generation of H2O2 from water and O2 under sunlight is a promising artificial photosynthesis reaction to generate renewable fuel. We previously found that resorcinol–formaldehyde resin powders prepared with a high-temperature hydrothermal method become semiconductors comprising π-conjugated/π-stacked benzenoid–quinoid donor–acceptor resorcinol units and are active for photocatalytic H2O2 generation. Here, we have prepared phenol–resorcinol–formaldehyde resins with small amounts of phenol (∼5 mol % relative to resorcinol), which show enhanced photocatalytic activity. Incorporating phenol bearing a single −OH group in the resin matrices relaxes the restriction on the arrangement of the aromatic rings originating from the H-bonding interactions between the resorcinol −OH groups. This creates stronger donor–acceptor π-stacking and increases the electron conductivity of the resins. We have demonstrated that simulated sunlight illumination of the resins in water under an atmospheric pressure of O2 stably generated H2O2 with more than 0.9% solar-to-chemical conversion efficiency.