Scalable preparation of defect-rich free-standing TiO2 sheets with visible-light photocatalytic activity

• Published in: Applied catalysis. B, Environmental Environmental, 2018-06, Vol.226, p.337-345
• Main Authors: Gao, Hanyang, Hu, Guoxin, Sui, Juan, Mu, Chao, Shangguan, Wenfeng, Kong, Min, Shentu, Wei
• Format: Article
• Language: English
• Subjects: Defect-rich; Flexible substrate; Free-standing; Hydrogenation; Self-assembled sheets; Visible-light responsible
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2017.12.055

[Display omitted] •A method for scalable preparing free-standing defective-rich TiO2 sheets was proposed.•Two-dimensional tiny defect-rich Ti□xO2-xδ− nanoplates were prepared by a simple method.•Ti□xO2-xδ+ nanoplates were self-assembled into free-standing sheets with aid of linker in freeze-drying process.•Self-assembled sheets were crystallized in free-standing defect-rich anatase sheets in hydrogenation process.•Anatase sheets were dispersed in water and coated on flexible substrate to form a visible-light-driven photocatalytic film. In this research, two interesting phenomena were reported and analyzed: First, two-dimensional tiny titania nanoplates (4–5 nm lateral size, 0.4–0.5 nm thickness) with rich edge-defects were found to self-assemble into free-standing thin sheets with large lateral size in a freeze-drying process with the aid of linker; Second, when subjected to a moderate hydrogenation treatment, these self-assembled sheets could be crystallized into integral anatase sheets while the edge-defects of the building blocks were maintained on the surface or inside the body of the crystal and the flexible sheet-like shape were also maintained. Based on these observations, a method for scalable preparing free-standing defect-rich TiO2 with a two-dimensional sheet-like morphology was proposed. The defects (oxygen vacancies) endowed the TiO2 a grayish-black color and visible-light responsibility. By using the dispersion of these defect-rich anatase sheets, a film could be densely deposited on flexible substrates in a layered structure and showed an efficient performance in acetaldehyde decomposition under the irradiation of visible light. Since it has always been a technical challenge to prepare crystallized visible-light-driven TiO2 films on plastic substrates with a low heat tolerance, this work may also provide a new approach to this problem.