Metal-Free Photocatalysts for Conversion of H₂ O into Hydrogen Peroxide

Hydrogen peroxide (H₂ O₂ ) is an important green oxidizing agent for environmental protection and chemical production. In comparison to the traditional anthraquinone method, photosynthesis is a green and energy-saving process for H₂ O₂ production. To improve the stability and practical application value of the H₂ O₂ synthesized by photocatalysis, the H₂ O₂ photosynthesis should be conducted in pure water without involving any sacrificial reagents. In this regard, organic semiconducting catalysts pose as a suitable candidate for photocatalytic H₂ O₂ synthesis owing to their metal-free nature to prevent H₂ O₂ decomposition by the metal ions. In this Perspective, the H₂ O₂ photosynthesis history is firstly introduced, followed by a review of the organic semiconductor photocatalysts reported to date. Finally, the main problems to thwart the advances of current pure H₂ O-to-H₂ O₂ photosynthesis are discussed, followed by proposed solutions to address these issues in order to pave new ways for the development of highly efficient metal-free organic photocatalysts for sustainable pure H₂ O-to-H₂ O₂ conversion.