Acta Chim. Sinica ›› 2019, Vol. 77 ›› Issue (6): 520-524.DOI: 10.6023/A19040108 Previous Articles     Next Articles

Article

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).

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