催化学报 ›› 2019, Vol. 40 ›› Issue (1): 60-69.DOI: 10.1016/S1872-2067(18)63170-5

• 论文 • 上一篇    下一篇

构建2D-2D TiO2纳米片/层状WS2异质结用以增强可见光响应光催化活性

吴勇川a, 刘中敏b, 李亚茹a, 陈继涛a, 主曦曦c, 那平a   

  1. a 天津大学化工学院, 天津 300350;
    b 德州大学化学与化学工程学院, 山东德州 253023;
    c 山东科技大学化学与环境工程学院, 山东青岛 266590
  • 收稿日期:2018-07-21 修回日期:2018-09-21 出版日期:2019-01-18 发布日期:2018-11-09
  • 通讯作者: 那平
  • 基金资助:

    国家高技术研究发展计划(863计划,2012AA063504);国家自然科学基金(U1407116,21511130020,21276193);天津市自然科学基金(13JCZDJC35600).

Construction of 2D-2D TiO2 nanosheet/layered WS2 heterojunctions with enhanced visible-light-responsive photocatalytic activity

Yongchuan Wua, Zhongmin liub, Yaru Lia, Jitao Chena, Xixi Zhuc, Ping Naa   

  1. a School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China;
    b College of Chemistry and Chemical Engineering, Dezhou University, Dezhou 253023, Shandong, China;
    c College of Chemistry and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, Shandong, China
  • Received:2018-07-21 Revised:2018-09-21 Online:2019-01-18 Published:2018-11-09
  • Contact: 10.1016/S1872-2067(18)63170-5
  • Supported by:

    This work was supported by the National High Technology Research and Development Program of China (863 Program, 2012AA063504), the National Natural Science Foundation of China (U1407116, 21511130020, 21276193), and the Tianjin Municipal Natural Science Foundation (13JCZDJC35600).

摘要:

自Fujishima等首次报道以来,TiO2作为一种重要的光催化剂引起了人们的广泛关注.迄今为止,研究人员已经开发出了各种形貌的具有不同晶型结构的TiO2,并用于光催化降解有机污染物.然而,TiO2的宽禁带(3.2eV)使其难以被可见光激活,导致对太阳光的利用效率低下.而且,在光催化反应中,低的量子效率无法满足实际应用.因此,开发具有可见光响应的高催化活性的TiO2基催化剂具有重要意义.集成复合材料、纳米材料和界面的优势构建纳米复合材料已成为提高TiO2光催化活性的重要策略.WS2具有典型的类石墨烯层状结构和窄的带隙(1.35eV),且其导带高于TiO2的导带,适合作为助催化剂修饰TiO2,使其具备可见光响应光催化活性.
本文采用一步水热法,以二维(2D)TiO2纳米片作基质材料,直接在其表面原位生长WS2层,制得了2D-2D TiO2纳米片/层状WS2(TNS/WS2)异质结.XRD及Raman结果表明,层状WS2与TiO2纳米片紧密结合在一起,且两者之间形成了W=O键.TEM结果显示,层状WS2以面-面堆叠方式均匀地包覆在TiO2纳米片表面,包覆层数约为4层.光催化性能测试结果表明,可见光照射下,TNS/WS2异质结对RhB的光催化降解能力高于原始TiO2纳米片和层状WS2,光催化活性得到明显增强.
紫外可见光谱试验结果显示,层状WS2的引入极大地增强了异质结的光吸收性能.PL光谱测试表明,TNS/WS2异质结具有更高效的载流子分离效率.为了进一步证实是光吸收性能的提升还是载流子分离效率的增强对光催化性能提起其主要作用,本文还研究了3D-2D TiO2空心微球/层状WS2(THS/WS2)复合材料.结果表明,TNS/WS2异质结比THS/WS2复合材料具有更高效的光生电子和空穴的分离能力.从而证明了TiO2纳米片与层状WS2之间完美的2D-2D纳米界面和紧密的界面结合,显著增加了载流子分离效率,因此光催化活性得到明显提高.
为了研究TNS/WS2异质结光催化剂的光催化机理,采用重铬酸钾、草酸铵、叔丁醇和对苯醌作自由基猝灭剂进行了自由基捕捉剂实验.结果表明,空穴在RhB降解过程中起主要作用,超氧自由基起次要作用.基于自由基猝灭实验结果和带隙结构分析,提出了TNS/WS2异质结对RhB的光催化机理为双转移光催化机理.可见,界面异质结工程化可能是制备高效和环境稳定的光催化剂的新思路.

关键词: WS2, TiO2, 纳米片, 异质结, 光催化, 可见光响应

Abstract:

Constructing nanocomposites that combine the advantages of composite materials, nanomaterials, and interfaces has been regarded as an important strategy to improve the photocatalytic activity of TiO2. In this study, 2D-2D TiO2 nanosheet/layered WS2 (TNS/WS2) heterojunctions were prepared via a hydrothermal method. The structure and morphology of the photocatalysts were systematically characterized. Layered WS2 (~4 layers) was wrapped on the surface of TiO2 nanosheets with a plate-to-plate stacked structure and connected with each other by W=O bonds. The as-prepared TNS/WS2 heterojunctions showed higher photocatalytic activity for the degradation of RhB under visible-light irradiation, than pristine TiO2 nanosheets and layered WS2. The improvement of photocatalytic activity was primarily attributed to enhanced charge separation efficiency, which originated from the perfect 2D-2D nanointerfaces and intimate interfacial contacts between TiO2 nanosheets and layered WS2. Based on experimental results, a double-transfer photocatalytic mechanism for the TNS/WS2 heterojunctions was proposed and discussed. This work provides new insights for synthesizing highly efficient and environmentally stable photocatalysts by engineering the surface heterojunctions.

Key words: WS2, TiO2, Nanosheet, Heterojunction, Photocatalysis, Visible-light responsive