Hydrogen peroxide (H₂O₂) is an important industrial chemical and a potential energy carrier. Photocatalytic synthesis of H₂O₂ is an attractive alternative to the traditional anthraquinone process for producing H₂O₂, but the catalyst systems that have been explored so far have many problems, including limited sunlight wavelength response, the need to sacrifice reagents, and insufficient activity.

Professor Yongfa Zhu’s team and others reported a self-assembled four (4-carboxyphenyl) porphyrin supramolecular photocatalyst that produces H₂O₂ from only H₂O and O₂, with quantum efficiencies of 14.9% and 1.1% at 420 nm and 940 nm, respectively. When simulated sunlight irradiation and heating were applied, the catalyst achieved a solar-to-chemical conversion efficiency of 1.2% at 328 K.

The results show that photo-generated electrons and holes promote H₂O₂ production by reacting at different active sites such as the pyrrole N-H ring and carboxyl groups. In particular, this paper proposes a hole-induced H₂O₂ generation process, which involves the -COOH on the catalyst being converted to -CO₃H under light, and then thermally decomposed.

The related work, titled “H₂O₂ generation from O₂ and H₂O on a near-infrared absorbing porphyrin supramolecular photocatalyst,” was published in Nature Energy."