催化学报 ›› 2021, Vol. 42 ›› Issue (1): 97-106.DOI: 10.1016/S1872-2067(20)63602-6

• 论文 • 上一篇    下一篇

具有高效电荷分离的2D/2D α-Fe2O3/Bi2WO6 S型异质结增强光-芬顿催化活性

王文亮a, 赵稳立a, 张灏纯a, 窦新城a, 史海峰a,b,*()   

  1. a江南大学理学院, 江苏无锡214122
    b江南大学江苏省轻工光电工程技术研究中心, 江苏无锡214122
  • 收稿日期:2020-02-28 接受日期:2020-04-08 出版日期:2021-01-18 发布日期:2021-01-18
  • 通讯作者: 史海峰
  • 基金资助:
    国家自然科学基金(21203077);国家自然科学基金(21773099);中央高校基本科研业务费(JUSRP51716A);江苏省青蓝工程项目

2D/2D step-scheme α-Fe2O3/Bi2WO6 photocatalyst with efficient charge transfer for enhanced photo-Fenton catalytic activity

Wenliang Wanga, Wenli Zhaoa, Haochun Zhanga, Xincheng Doua, Haifeng Shia,b,*()   

  1. aSchool of Science, Jiangnan University, Wuxi 214122, Jiangsu, China
    bJiangsu Provincial Research Center of Light Industrial Optoelectronic Engineering and Technology, Jiangnan University, Wuxi 214122, Jiangsu, China
  • Received:2020-02-28 Accepted:2020-04-08 Online:2021-01-18 Published:2021-01-18
  • Contact: Haifeng Shi
  • About author:*Tel: +86-15052262655; E-mail: hfshi@jiangnan.edu.cn
  • Supported by:
    National Natural Science Foundation of China(21203077);TNational Natural Science Foundation of China(21773099);Fundamental Research Funds for the Central Universities(JUSRP51716A);Qing Lan Project of Jiangsu Province

摘要:

近年来, Fenton反应由于其成本低, 反应速度快, 操作简单等优势受到了广泛的研究. 传统的均相Fenton反应可通过H2O2氧化Fe2+产生具有强氧化性的羟基自由基, 用于处理难降解的有机物. 然而, Fenton反应存在两个主要问题, 首先, 在Fenton反应中需要加入大量的酸来维持酸性环境, 以保证反应的最佳活性. 其次, Fenton反应中铁离子不断流失并形成固体污泥, 这严重影响了Fenton反应产生•OH的效率. 目前, 将光催化反应与非均相芬顿反应相结合是改善这些问题的有效方案. 非均相光芬顿反应不仅能提高有机物降解的活性, 而且通过光催化剂导带上的电子有效减少Fe3+的浸出和铁氢氧化物沉淀的产生.
最近, 作为一种可见光Fenton催化剂, α-Fe2O3可以在几乎中性的条件下发生光芬顿反应, 这解决了在反应过程中需要随时调整PH值的问题. 此外, 光照条件下α-Fe2O3价带上的电子能跃迁至导带并将Fe 3+还原成Fe2+, 从而减少铁离子的损耗. 然而, 由于光生载流子复合率较高等问题, 单一α-Fe2O3光催化剂的催化活性仍不理想. 构建具有2D/2D结构的S型异质结可以缩短电子在界面间的传输距离, 增大材料的活性位点, 将光生电子-空穴在空间上分离, 从而有效增强光生载流子的分离效率. 因此, 构建2D/2D α-Fe2O3/Bi2WO6 S型异质结, 并用于光芬顿反应有望进一步提高对有机污染物的降解效率.
本文通过简易的水热法制备了具有2D/2D结构的α-Fe2O3/Bi2WO6 S型异质结光芬顿催化剂, 并通过XRD、BET、TEM、XPS和UV-Vis等手段对催化剂的晶体结构、元素状态、微观结构、光学性质和化学组分进行了表征. 通过在可见光照射下降解甲基蓝(MB), 考察了α-Fe2O3/Bi2WO6的光芬顿催化活性. 结果表明, 由于光催化反应与Fenton反应的协同作用, α-Fe2O3/Bi2WO6表现出了明显增强的光-Fenton催化活性, 最佳比例的α-Fe2O3/Bi2WO6的活性分别是单一α-Fe2O3和Bi2WO6的11.06倍和3.29倍. 本文将光催化反应与Fenton反应相结合, 一方面, 光催化反应对Fe3+的还原有促进作用,提高了Fe2+的浓度, 从而提升羟基自由基的产量; 另一方面, Fenton反应对α-Fe2O3/Bi2WO6中电子的利用阻止了光生载流子的复合,进一步提高了光催化降解效率. 此外, 由于二维纳米片之间具有更大的接触面积, 2D/2D异质结可以缩短电荷传输时间和距离, 促进了光生电子-空穴的分离. 同时, 具有较大比表面积的2D/2D材料可以在催化剂表面提供大量用于有机物氧化分解的活性位点. 而S型异质结的构建不但促进了界面电荷的转移和分离, 还能维持最佳的电荷氧化还原电位, 这都提升了催化剂的光芬顿催化活性. 总之, 本文为合成可高效降解有机污染物的非均相光-芬顿催化剂提供了新的思路.

关键词: Bi2WO6, α-Fe2O3, S型异质结, 光芬顿, 2D光催化剂

Abstract:

Although the traditional Fenton reaction is considered an effective strategy for solving problems caused by environmental pollution, construction of an efficient photocatalytic system by coordinating the Fenton reaction is challenging. In this study, 2D/2D step-scheme α-Fe2O3/Bi2WO6 (FO/BWO) heterostructure photo-Fenton catalysts were successfully fabricated by a facile hydrothermal method. The as-prepared materials were characterized by XRD, FT-IR, TEM, XPS, UV-vis DRS, PL, I-t, EIS, and BET analyses. Under visible light irradiation, FO/BWO exhibited remarkably high and stable photo-Fenton catalytic activity for the degradation of methyl blue (MB) at low concentrations of H2O2. It was noted that FO/BWO (0.5) displayed a significantly enhanced photo-Fenton catalytic activity, which was 11.06 and 3.29 times those of FO nanosheets and BWO nanosheets, respectively. The notably improved photo-Fenton catalytic activity of FO/BWO was mainly due to the combination of H2O2 and FO under light illumination and the presence of the 2D/2D S-scheme heterostructure, with the large contact surface, abundant active sites, and efficient separation rate of photogenerated carriers playing contributory roles. Additionally, a possible catalytic mechanism for the FO/BWO composite was preliminarily proposed via active species trapping experiments. In summary, this study provided new insights into the synthesis of an effectively heterogeneous 2D/2D S-scheme photo-Fenton catalyst for degradation of organic pollutants in wastewater.

Key words: Bi2WO6, α-Fe2O3, S-scheme, Photo-Fenton, 2D photocatalyst