化学学报 ›› 2019, Vol. 77 ›› Issue (6): 520-524.DOI: 10.6023/A19040108 上一篇    下一篇

研究论文

TiO2/石墨烯复合材料的光生电荷分离调控与光催化产氢性能研究

郭宇a, 李燕瑞b, 王成名a, 龙冉a, 熊宇杰a   

  1. a 中国科学技术大学 化学与材料科学学院 合肥微尺度物质科学国家研究中心 合肥 230026;
    b 西安交通大学 国际可再生能源研究中心动力工程多相流国家重点实验室 西安 710049
  • 收稿日期:2019-04-01 出版日期:2019-06-15 发布日期:2019-04-30
  • 通讯作者: 李燕瑞, 龙冉, 熊宇杰 E-mail:liyanrui91@mail.xjtu.edu.cn;longran@ustc.edu.cn;yjxiong@ustc.edu.cn
  • 基金资助:

    项目受国家重点研发计划(Nos.2017YFA0207301,2017YFA0207302)和国家自然科学基金(Nos.21725102,U1832156,21601173,21573212)资助.

Photogenerated Charge Separation and Photocatalytic Hydrogen Production of TiO2/Graphene Composite Materials

Guo Yua, Li Yanruib, Wang Chengminga, Long Rana, Xiong Yujiea   

  1. a School of Chemistry and Materials Science, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026;
    b International Research Centre for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049
  • Received:2019-04-01 Online:2019-06-15 Published:2019-04-30
  • Supported by:

    Project supported by the National Key Research & Development Program of China (Nos. 2017YFA0207301, 2017YFA0207302) and the National Natural Science Foundation of China (Nos. 21725102, U1832156, 21601173, 21573212).

半导体光生电荷分离是光催化过程中的关键步骤之一,其效率极大地影响了最终光催化性能.将TiO2纳米片与石墨烯复合,能够促进TiO2中光生电子和空穴的分离,从而提高其光催化活性.为了研究光生电荷的分离对TiO2/石墨烯复合材料光催化性能的影响,通过调控TiO2纳米片的尺寸来调节TiO2/石墨烯复合材料中光生电荷分离的能力,然后研究其对TiO2/石墨烯复合材料光催化性能的影响.合成了一系列不同厚度的TiO2纳米片,将其与石墨烯复合,并通过光沉积负载Pt纳米颗粒作为助催化剂,用于光催化产氢.实验结果显示,随着TiO2纳米片厚度减小,其与石墨烯形成的复合结构的光催化性能显著提高.这主要是由于TiO2纳米片厚度减小时,光生电子沿厚度方向穿过TiO2纳米片迁移到石墨烯的距离缩短,从而减少了光生电子在迁移过程中与空穴的复合;同时TiO2纳米片厚度减小使其比表面积增大,使得TiO2/石墨烯界面面积增大,从而使石墨烯更好地分离出TiO2中的光生电子,有更多的光生电子到达石墨烯参与催化反应,提高TiO2/石墨烯复合材料的光催化性能.此研究表明通过控制TiO2纳米片的尺寸来调控TiO2/石墨烯复合材料中光生电子和空穴的分离,是显著提高其光催化性能的有效途径.

关键词: TiO2纳米片/石墨烯, 光生电荷分离, 纳米片尺寸, 电子迁移, 界面

Separation of photogenerated charges is one of the key steps in photocatalysis, whose efficiency largely determines the overall photocatalytic performance in water splitting. It is known that the formation of hybrid nanostructures is a promising solution to improve photocatalytic performance. However, the chemical environment difference during the synthesis of hybrid nanostructures may bring additional influencing factors to material systems. In this case, the design and synthesis of well-defined and clean samples are highly important to fundamental investigations. Integrating TiO2 nanosheets with graphene can enhance the photocatalytic activity of TiO2 through the effective separation of the photogenerated electrons and holes across the interface formed by C-O bonds. To investigate the influence of photogenerated charge separation on the photocatalytic performance of TiO2/graphene composites, we modulate the separation of the photogenerated charges by controlling the size and thickness of TiO2 nanosheets with the same chemical environment, which helps investigate its effect on the photocatalytic performance of TiO2/graphene composites. Specifically, a series of TiO2 nanosheets with different thickness are synthesized by controlling the amount of hydrofluoric acid and combined with graphene for photocatalytic hydrogen production. The hybrid nanostructures are formed through a simple and clean process so as to possess a reliable platform for evaluating the relationship between structural parameters and performance in photocatalytic hydrogen production. The experiment results show that the photocatalytic activity of TiO2/rGO composites increases with the reduction in the thickness of TiO2 nanosheets. As the thickness of TiO2 nanosheets decreases, the migration distance of the photo-excited electrons is reduced so as to effectively suppress the recombination of the photo-excited charges. In the meanwhile, the TiO2/graphene interface is enlarged to promote the separation of the photogenerated charges in TiO2. As a result, the utilization efficiency of the photogenerated charges has been substantially enhanced. This work demonstrates that modulating the separation of photogenerated charges in TiO2/graphene composites by controlling the size of TiO2 nanosheets is an effective strategy for improving the photocatalytic performance of TiO2/graphene composites.

Key words: TiO2 nanosheet/graphene, photogenerated charge separation, nanosheet size, electron migration, interface