Metal-Free Photocatalysts for Conversion of H 2 O into Hydrogen Peroxide.

Hydrogen peroxide (H 2 O 2 ) 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 H 2 O 2 production. To improve the stability and practical application value of the H 2 O 2 synthesized by photocatalysis, the H 2 O 2 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 H 2 O 2 synthesis owing to their metal-free nature to prevent H 2 O 2 decomposition by the metal ions. In this Perspective, the H 2 O 2 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 H 2 O-to-H 2 O 2 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 H 2 O-to-H 2 O 2 conversion.