物理化学学报 >> 2017, Vol. 33 >> Issue (12): 2532-2541.doi: 10.3866/PKU.WHXB201706153

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熔盐辅助微波法制备g-C3N4包覆MgO-Al2O3-Fe2O3异质结催化剂及其光催化制过氧化氢性能

陈鑫,胡绍争*(),李萍,李薇,马宏飞,陆光   

  • 收稿日期:2017-05-09 发布日期:2017-09-05
  • 通讯作者: 胡绍争 E-mail:hushaozhenglnpu@163.com
  • 基金资助:
    国家自然科学基金(41571464);辽宁省教育厅项目(L2014145);辽宁省自然科学基金项目(201602467)

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 E-mail:hushaozhenglnpu@163.com
  • 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)

摘要:

工业上,双氧水的生产采用的是蒽醌法。此方法采用多步加氢和氧化过程,因此能耗很大。光催化制过氧化氢技术作为可持续和环境友好的新工艺,是传统蒽醌和电化学法的优秀替代者。本文采用熔盐辅助微波法制备了g-C3N4包覆MgO-Al2O3-Fe2O3异质结催化剂。制备的异质结催化剂在可见光下表现出优异的光催化制过氧化氢性能。熔盐的引入改变催化剂形貌的同时也影响了原料三聚氰胺的缩聚度,进而影响了其能带结构。制备的包覆结构能使两组分形成最大面积的异质结和强相互作用。这种强相互作用有利于光生电子-空穴对的分离和界面迁移,进而提高了过氧化氢的生成速率。制备的异质结催化剂的双氧水平衡浓度和生成速率分别为6.3 mmol·L-1和1.42 mmol·L-1·h-1,远高于两个单组份。不仅如此,制备的异质结催化剂还能抑制过氧化氢的分解。本文通过自由基捕获实验探讨了可能的反应机理和电子转移路径。

关键词: 石墨相氮化碳, 包覆结构, 异质结, 制过氧化氢, 熔盐辅助微波法

Abstract:

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

MSC2000: 

  • O643