Inorganic Metal-Oxide Photocatalyst for H2O2 Production

Hydrogen peroxide (H2O2) is a mild but versatile oxidizing agent with extensive applications in bleaching, wastewater purification, medical treatment, and chemical synthesis. The state-of-art H2O2 production via anthraquinone oxidation is hardly considered a cost-efficient and environment-friendly process because it requires high energy input and generates hazardous organic wastes. Photocatalytic H2O2 production is a green, sustainable, and inexpensive process which only needs water and gaseous dioxygen as the raw materials and sunlight as the power source. Inorganic metal oxide semiconductors are good candidates for photocatalytic H2O2 production due to their abundance in nature, biocompatibility, exceptional stability, and low cost. Progress has been made to enhance the photocatalytic activity toward H2O2 production, however, H2O2 photosynthesis is still in the laboratory research phase since the productivity is far from satisfaction. To inspire innovative ideas for boosting the H2O2 yield in photocatalysis, the most well-studied metal oxide photocatalysts are selected and the modification strategies to improve their activity are listed. The mechanisms for H2O2 production over modified photocatalysts are discussed to highlight the facilitating role of the modification methods. Besides, methods for the quantification of H2O2 and associated radical intermediates are provided to guide future studies in this field.

Automated summary

Hydrogen peroxide is a versatile oxidizing agent used in various applications, with its production via anthraquinone oxidation process being considered inefficient and environmentally unfriendly. Photocatalytic production of H2O2 using inorganic metal oxide semiconductors is a green and cost-effective alternative, although productivity is still a challenge in laboratory research. Efforts are being made to enhance the photocatalytic activity for H2O2 production, with modifications and quantification methods being explored for future advancements in this field.