催化学报

催化学报 ›› 2019, Vol. 40 ›› Issue (5): 776-785.DOI: 10.1016/S1872-2067(19)63300-0

• 论文 • 上一篇    下一篇

Mg/O共同修饰无定形氮化碳的独特电子结构增强光催化对四环素盐酸盐的降解

吴晓璐, 傅敏, 卢鹏, 任秋燕, 汪成   

  1. 重庆工商大学环境与资源学院, 重庆市催化与环境新材料重点实验室, 重庆 400067
  • 收稿日期:2018-12-10 修回日期:2019-01-09 出版日期:2019-05-18 发布日期:2019-03-30
  • 通讯作者: 傅敏
  • 基金资助:

    重庆市社会民生科技创新专项（cstc2016shmszx20012）；重庆市高校优秀成果转化资助项目（KJZH17122）；国家自然科学基金（5160080705）；重庆工商大学重点实验室开放项目（1556036）；重庆市教委科学技术研究项目（KJ130704）；重庆工商大学创新型科研项目（yjscxx2016-060-34）.

Unique electronic structure of Mg/O co-decorated amorphous carbon nitride enhances the photocatalytic tetracycline hydrochloride degradation

Xiaolu Wu, Min Fu, Peng Lu, Qiuyan Ren, Cheng Wang   

  1. College of Environment and Resources, Chongqing Key Laboratory of Catalysis and New Environmental Materials, Chongqing Technology and Business University, Chongqing 400067, China
  • Received:2018-12-10 Revised:2019-01-09 Online:2019-05-18 Published:2019-03-30
  • Contact: S1872-2067(19)63300-0
  • Supported by:

    This work was supported by the Specialized Innovation of Social and People's Livelihood in Chongqing (cstc2016shmszx20012), Converting Outstanding Achievements of University-Funded Projects of Chongqing (KJZH17122), the National Natural Science Foundation of China (5160080705), the Key Laboratory Open Project from Chongqing Technology and Business University (1556036), the Scientific and Technological Research Program of Chongqing Municipal Education Commission (KJ130704), and Innovative Research Project from Chongqing Technology and Business University (yjscxx2016-060-34)

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摘要：

近年来，光催化技术被广泛应用于环境和能源领域.其中，g-C3N4因化学稳定性和热稳定性好、能带结构易调控而成为一种有前景的可见光光催化剂.然而，g-C3N4的电子-空穴对易复合，导致其不能充分利用太阳光，光催化效率并不理想.本文通过实验与理论结合的方法设计并制备了具有独特电子结构的Mg/O共同修饰的无定形氮化碳（记为MgO-CN），以30 mg/L的四环素盐酸溶液（TC）作为目标污染物评价了其光催化性能.经X射线衍射、扫描电镜、透射电镜、N2物理吸附、紫外-可见光谱等表征手段分析表明，MgO-CN样品（002）晶面的衍射峰强度随着MgO含量增加而减弱，CN趋向于无定形化.同时，MgO-CN样品的可见光吸收边带发生红移，呈现出更强的可见光吸收能力.此外，Mg原子和O原子共同修饰的独特电子结构可以通过C→O←Mg的电子传递路线在O原子周围产生局域电子，从而抑制电子-空穴的复合.
光催化降解TC的实验结果表明，在可见光照射后，含有1.2 wt% MgO的复合样品MgO-CN-1.2具有最佳光催化活性，TC降解效率为82.0%，比g-C3N4的光催化效率（23.5%）高出58.5%，且光催化降解过程符合准一级动力学，MgO-CN-1.2的反应速率常数（0.01018 min-1）是g-C3N4（0.00205 min-1）的5倍.自由基捕获测试实验表明，g-C3N4和MgO-CN-1.2样品均可以产生·O2-自由基和·OH自由基，但是MgO-CN-1.2样品的·O2-和·OH信号更强.这是由于MgO-CN-1.2样品可以吸收更大范围的可见光用于激发电子，同时结合理论计算证明，MgO-CN内部电子在O原子周围汇集，形成的电子定向传输通道对催化剂表面的电子-空穴复合有抑制作用，更加有利于电子的迁移而诱导O2生成·O2-.由于MgO-CN-1.2和g-C3N4的价带位置分别位于1.47和1.60 eV，此价带上的h+不能与H2O和OH-直接反应生成·OH，而是由生成的·O2-再与H+和e-按照O2→·O2 → H2O2→·OH的反应途径生成·OH.本文最后分析，MgO-CN复合物参与反应的主要活性物种为·O2-，·OH和h+光催化降解污染物的反应机理.其中，·O2-对光催化降解TC的贡献最大，为最主要的活性物质.本文工作提供了一种新的策略来改变氮化碳的电子结构，对提高其催化性能具有积极意义.

关键词: 氮化硅, 电子结构, 可见光光催化, 四环素盐酸盐降解, 环境修复

Abstract:

g-C3N4 is a hot visible light photocatalyst. However, the fast recombination of photogenerated electron-hole pairs leads to unsatisfactory photocatalytic efficiencies. In this study, Mg/O co-decorated amorphous carbon nitride (labeled as MgO-CN) with a unique electronic structure was designed and prepared via a combined experimental and theoretical approach. The results showed that the MgO-CN exhibited an increased light absorption ability and promoted charge separation efficiency. The Mg and O co-decoration created a unique structure that could generate localized electrons around O atoms and enhance the reactant activation capacities via the C→O←Mg route. This could dramatically promote the O2 molecule activation on the catalyst surface to generate reactive species (·O2-/·OH). The optimized MgO-CN exhibited a high photocatalytic activity for the degradation of tetracycline hydrochloride in water, which was five times higher than that of pristine g-C3N4. The present work could provide a new strategy for modifying the electronic structure of g-C3N4 and enhancing its performance for environmental applications.

Key words: g-C3N4, Electronic structure, Visible light photocatalysis, Tetracycline hydrochloride degradation, Environmental remediation