Influence of calcination temperature on photocatalytic H₂O₂ productivity of hierarchical porous ZnO microspheres

Abstract

Photocatalytic production of H 2 O 2 from water and atmospheric oxygen has been recognized as a green and sustainable chemical process, due to the abundance of raw materials and sustainable solar energy. Herein, flower-like hierarchical ZnO microspheres were prepared by hydrothermal method followed by calcination at different temperatures, and their photocatalytic performance in H 2 O 2 production was examined under simulated sunlight irradiation. The calcination temperature plays a vital role in the structure, morphology, and surface area of the final ZnO products as well as their optical and electrochemical properties, which are determining factors in their photocatalytic activity. The ZnO calcined at 300 °C (Zn-300) exhibits the highest activity and optimal stability, showing productivity of 2793 μmol l −1 within 60 min of irradiation, which was 6.5 times higher than that of uncalcined ZnO precursor. The remarkable photocatalytic activity is attributed to enhanced light utilization, large surface area, abundant exposed active sites, improved separation efficiency, and prolonged carrier lifespan. Moreover, the results from cycling experiments indicate the as-prepared ZnO samples exhibit good stability and long-time performance. This work provides useful information for the preparation of hierarchical ZnO photocatalysts.

Hierarchically Porous ZnO/g-C3N4 S-Scheme Heterojunction Photocatalyst for Efficient H2O2 Production

“…Photocatalytic H 2 O 2 production is a low-cost and sustainable pathway where H 2 O 2 is produced by the reduction of O 2 (eq ) on the surfaces of photocatalysts . Generally, the holes (h + ) in the valence band (VB) of the photocatalyst are used to oxidize H 2 O to H + and O 2 (eq ), while the electrons (e – ) in the conduction band (CB) participate in the O 2 reduction reaction (ORR).…”

“…Photocatalytic H 2 O 2 production is a low-cost and sustainable pathway where H 2 O 2 is produced by the reduction of O 2 (eq 1) on the surfaces of photocatalysts. 7 Generally, the holes (h + ) in the valence band (VB) of the photocatalyst are used to oxidize H 2 O to H + and O 2 (eq 2), while the electrons (e − ) in the conduction band (CB) participate in the O 2 reduction reaction (ORR). There are two types of ORRs that generate H 2 O 2 : the first is the single-step two-electron reduction of O 2 (eq 3), and the other is the stepwise single-electron reduction of O 2 (eqs 4 and 5).…”

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

“…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 . Among them, ZnO, featured with non-toxicity, stability and earth-abundance, has attracted much interest 33 , but it still suffers from poor absorption of sunlight and fast recombination of photoinduced charge carriers 34 .…”

Review of S-Scheme Heterojunction Photocatalyst for H₂O₂ Production

“…As an effective, multifunctional and green oxidizer, hydrogen peroxide (H2O2) is used in lots of applications, such as pollutant purification, medical disinfection and chemical synthesis. In addition, H2O2 can also be utilized as the high-density energy carrier for fuel cells [42][43][44] . Currently, commercial H2O2 is mainly achieved by conventional anthraquinone oxidation, which is not only costly and energy intensive, but also produces the toxic byproducts.…”