催化学报

催化学报 ›› 2020, Vol. 41 ›› Issue (10): 1564-1572.DOI: 10.1016/S1872-2067(19)63518-7

• 论文 • 上一篇    下一篇

Fe(III)螯合掺杂对g-C3N4光催化性能和活性位的影响

刘桂梅a, 董国辉b, 曾玉彬a, 王传义b   

  1. a 武汉大学动力与机械学院, 湖北武汉 430072;
    b 陕西科技大学环境科学与工程学院, 陕西西安 710021
  • 收稿日期:2019-09-09 修回日期:2019-09-27 出版日期:2020-10-18 发布日期:2020-08-15
  • 通讯作者: 董国辉, 曾玉彬, 王传义
  • 基金资助:
    国家自然科学基金（21876104，21603271，U1703129）.

The photocatalytic performance and active sites of g-C3N4 effected by the coordination doping of Fe(III)

Guimei Liua, Guohui Dongb, Yubin Zenga, Chuanyi Wangb   

  1. a Hubei Key Laboratory of Accoutrement Technique in Fluid Machinery and Power Engineering, Wuhan University, Wuhan 430072, Hubei, China;
    b School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an 710021, Shaanxi, China
  • Received:2019-09-09 Revised:2019-09-27 Online:2020-10-18 Published:2020-08-15
  • Supported by:
    This work was supported by the National Nature Science Foundation of China (21876104, 21603271, U1703129) are gratefully appreciated.

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摘要： 元素掺杂是一种简单有效的光催化剂改性方法.已有诸多文献报道采用非金属元素（B、P、S）或金属元素（Na+，Ni3+，Co3+，Cu2+）对g-C3N4进行掺杂改性，但目前对金属掺杂的模型和影响机理尚不清晰.g-C3N4作为层状材料，它的表面和边缘有大量的胺基，它对光生载流子的传输起到重要作用.此外，胺基可以与金属通过配位键形成螯合物；与胺基螯合的金属由于其功函数较小，可以捕获半导体的光生电子，并有利于降低光生载流子的复合.本文选用Fe（III）对g-C3N4进行掺杂改性，SEM-EDS表明，C和N元素均匀分布在g-C3N4整个骨架上，而Fe元素主要分布在g-C3N4边缘部分；FTIR结果发现，掺杂Fe后，N-Hx伸缩振动峰强度随着掺杂量的增加而降低，证明Fe（III）与g-C3N4表面胺基之间形成配位键，即Fe（III）掺杂为螯合掺杂.Fe（III）螯合掺杂后的g-C3N4光催化氧化RhB和光催化还原Cr（VI）的性能都得到显著提升.这是因为螯合掺杂Fe（III）后，g-C3N4不仅产生了更多的光生电子，而且由于产生的Fe（II）的芬顿效应产生了更多的羟基自由基，极大地提升了g-C3N4光催化氧化还原性能.但是Fe（III）螯合掺杂后却抑制了g-C3N4光催化去除NO的性能，NO去除性能随着Fe（III）掺杂量的增加而下降，这与Fe（III）的螯合掺杂模型有密切关系.NO-TPD实验结果表明，Fe掺杂降低了g-C3N4对NO的吸附；但脱氨基实验证明胺基对NO吸附并无作用.通过EPR表征发现，掺杂Fe后C的Lorentzian线强度降低了2/3，说明C上的未成对电子减少.同时通过固体NMR（1H谱）中发现掺杂后N-H2减少、但C-H数量增多的规律.说明Fe（III）与表面胺基（N-H2）螯合后，质子占据C活性位，而C活性位却是NO在g-C3N4表面的吸附位点.所以Fe（III）的螯合掺杂会降低g-C3N4光催化去除NO的性能.
综上，Fe（III）螯合掺杂可以提高g-C3N4的氧化还原能力，但是并不适用于所有的光催化反应.同时，关注不理想的活性变化有助于进一步挖掘改性方法对材料结构的影响，指导改性材料的使用，并可能为其它相关研究带来启发.

关键词: 螯合掺杂, g-C3N4, 光催化, Fe(III), 一氧化氮去除

Abstract: Element doping is a simple and effective method to improve photocatalytic activity of g-C3N4. However, the doping model and mechanism of metal elements are still uncharacterized. In this study, we found that Fe(III) can be doped into g-C3N4 through the coordination between amidogen and Fe(III). After activity tests, it was found that this coordination doping of Fe(III) could enhance the RhB oxidation and Cr(VI) reduction activities of g-C3N4 in interesting ways, but it is not helpful for the NO-removal performance of g-C3N4. Characterization and calculation results show that the coordination of Fe(III) can not only improve the transfer of photogenerated electrons, but it also can passivate the carbon site of triazine rings, which is the active site of NO-removal. This study revealed some doping mechanisms and effect mechanisms of elemental metal in photocatalysis.

Key words: Doping, g-C3N4, Photocatalysis, Fe ion, NO removal