Acta Phys. -Chim. Sin. ›› 2017, Vol. 33 ›› Issue (12): 2532-2541.doi: 10.3866/PKU.WHXB201706153

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Photocatalytic Production of Hydrogen Peroxide Using g-C3N4 Coated MgO-Al2O3-Fe2O3 Heterojunction Catalysts Prepared by a Novel Molten Salt-Assisted Microwave Process

Xin CHEN,Shao-Zheng HU*(),Ping LI,Wei LI,Hong-Fei MA,Guang LU   

  • Received:2017-05-09 Published:2017-09-05
  • Contact: Shao-Zheng HU
  • Supported by:
    the National Natural Science Foundation of China(41571464);Education Department of Liaoning Province, China(L2014145);Natural Science Foundation of Liaoning Province, China(201602467)


H2O2 is industrially produced by the anthraquinone method, in which energy consumption is high because it involves multistep hydrogenation and oxidation reactions. Photocatalytic production of H2O2 has received increasing attention as a sustainable and eco-friendly alternative to conventional anthraquinone-based and electrochemical production processes. Herein, we report a novel molten salt-assisted microwave process for the synthesis of a g-C3N4-coated MgO-Al2O3-Fe2O3 (MAFO) heterojunction photocatalyst with outstanding H2O2 production ability. The addition of a molten salt during synthesis changes the morphology of the as-prepared catalysts and influences the degree of polycondensation of melamine, leading to a change in the band gap energy. The cladding structure forms the maximum area of the heterojunction, leading to strong electronic coupling between the two components. This strong electronic coupling results in a more effective separation of the photogenerated electron-hole pairs and a faster interfacial charge transfer, leading to higher H2O2 formation rate. The equilibrium concentration and formation rate of H2O2 over the as-prepared heterojunction catalyst were 6.3 mmol·L-1 and 1.42 mmol·L-1·h-1, which are much higher than that reported for g-C3N4 and MAFO individually. In addition, the H2O2 decomposition rate also decreases over the as-prepared heterojunction catalysts. A possible mechanism and the electron transfer routes have been proposed based on a free radical trapping experiment.

Key words: g-C3N4, Cladding structure, Heterojunction, H2O2 production, Molten salt-assisted microwave process