Inorganic Metal‐Oxide Photocatalyst for H₂O₂ Production

Abstract

Hydrogen peroxide (H 2 O 2 ) is a mild but versatile oxidizing agent with extensive applications in bleaching, wastewater purification, medical treatment, and chemical synthesis. The state-of-art H 2 O 2 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 H 2 O 2 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 H 2 O 2 production due to their abundance in nature, biocompatibility, exceptional stability, and low cost. Progress has been made to enhance the photocatalytic activity toward H 2 O 2 production, however, H 2 O 2 photosynthesis is still in the laboratory research phase since the productivity is far from satisfaction. To inspire innovative ideas for boosting the H 2 O 2 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 H 2 O 2 production over modified photocatalysts are discussed to highlight the facilitating role of the modification methods. Besides, methods for the quantification of H 2 O 2 and associated radical intermediates are provided to guide future studies in this field.

Enhanced Photocatalytic H₂O₂ Production over Inverse Opal ZnO@ Polydopamine S-scheme Heterojunctions

“…Currently, H2O2 is produced via anthraquinone (AQ) process [8][9][10] , direct hydrogen-oxygen reaction 11,12 and oxidation of alcohols 13,14 . These methods either demand high energy input or cause environmental pollution, which significantly hinder their largescale application [15][16][17] . Thus, it is urgent to develop an economic, efficient and eco-friendly method.…”

“…Photocatalysis is a green and sustainable method to produce H2O2 since it is powered by inexhaustible sunlight 18 . Moreover, it also reduces our energy reliance on unsustainable fossil fuels and alleviates environmental pollution 15,19,20 . To date, various semiconductors have been developed for photocatalytic H2O2 production, including TiO2 13,16,21 , ZnO [22][23][24] , g-C3N4 [25][26][27] , CdS 28,29 , graphene 30,31 and BiVO4 32 .…”

Direct synthesis of triphenylamine-based ordered mesoporous polymers for metal-free photocatalytic aerobic oxidation

“…As speculated, the precursor TPA1, which mainly absorbed UV light, almost showed no photocatalytic reactivity (Table 2, entry 7). Moreover, control experiments revealed that in the absence of TPA-MPs, visible-light, air or citric acid, the reaction proceeded rather sluggishly and only a small amount of the product was obtained (Table 2, entries [8][9][10][11]. These control experiments demonstrated that the TPA-MP catalyst, visible-light, air and citric acid decisively contribute to the photocatalytic reaction.…”

“…4 Thus, it is still highly desirable to develop efficient heterogeneous photocatalysts that are free of precious metals, inexpensive, stable, and recyclable, to decrease the processing costs in large-scale synthesis. 5 To this end, nonprecious metal-based semiconductors (such as bismuth-based nanomaterials, 6 metal sulfides, 7 metal oxides, 8 transition metal dichalcogenides, 9 etc. ) have emerged as promising candidates for replacing expensive and toxic precious metal-based complexes and organic dyes, which, however, are facing problems such as limited visible-light absorption and photocorrosion.…”

Self-reporting of damage in underwater hierarchical ionic skinsviacascade reaction-regulated chemiluminescence

“…The water-induced H 2 O 2 production and the H 2 O 2 -induced luminescence were experimentally studied using single-layered ionogel films (size: 13 mm  7 mm  0.5 mm). An ionogel film containing CaO 2 was placed in deionized water and the H 2 O 2 production was monitored by the cerium sulfate titration method 43,44 using a previously established calibration curve (Fig. S5, ESI †).…”