Tuning Stark effect by defect engineering on black titanium dioxide mesoporous spheres for enhanced hydrogen evolution

• Published in: Chinese chemical letters Vol. 35; no. 11; pp. 110254 - 259
• Main Authors: Zhang, Bingke, Wang, Dongbo, Cao, Jiamu, He, Wen, Liu, Gang, Liu, Donghao, Zhao, Chenchen, Pan, Jingwen, Liu, Sihang, Zhang, Weifeng, Fang, Xuan, Zhao, Liancheng, Wang, Jinzhong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2024; School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001,China%School of Astronautics,Harbin Institute of Technology,Harbin 150001,China%Center for High Pressure Science and Technology Advanced Research,Shanghai 201203,China%Qingdao University of Science and Technology,Qingdao 266061,China%State Key Laboratory of High Power Semiconductor Lasers,School of Physics,Changchun University of Science and Technology,Changchun 130022,China
• Subjects: Carrier localization; Defect; Photocatalysis; Stark effect; TiO2−X; Defect; Carrier localization; TiO2−X; Stark effect; Photocatalysis; TiO2-X
• DOI: 10.1016/j.cclet.2024.110254
• ISSN: 1001-8417

Defects can strongly affect the lattice, strain, and electronic structures of nanomaterials photocatalysts, like a double-edged sword of both positive significance and negative influence on photocatalytic performances. To date, most studies into defects only partially elucidated their beneficial or detrimental roles in photocatalysis. However, a quantitative understanding of the photocatalytic performances modulated by defect concentration still needs to be discovered. Here, a series of TiO2−X mesoporous spheres (MS) with different oxygen vacancy concentrations for photocatalytic applications were prepared by high-temperature chemical reduction. The link between oxygen vacancy concentration and photocatalytic performance was successfully established. The localization of carriers dominated by the Stark effect is first enhanced and then weakened with increasing oxygen vacancy concentration, which is a crucial factor in explaining the double-edged sword role of defect concentration in photocatalysis. As the reduction temperature rises to 300 °C, carrier localization dominated by the quantum-confined Stark effect maximizes the separation ability of photo generated electron hole pairs, thus exhibiting the best catalytic performance for photocatalytic hydrogen production and the degradation of organic pollutants, as demonstrated by a hydrogen evolution rate of 523.7 µmol g-1 h-1 and a ninefold higher RhB photodegradation rate compared to TiO2 MS. The work offers excellent flexibility for precisely constructing high-performance photocatalysts by understanding vacancy engineering. We propose an optimal defect doping level to enhance the Stark effect, promoting the separation of electron-hole pairs and thereby improving photocatalytic performance. [Display omitted]