Preparation of WO3-modified TiO2 thin film by peroxo sol–gel method and its photocatalytic activity in degradation of methylene blue

• Published in: Research on chemical intermediates 2020-10, Vol.46 (10), p.4627-4643
• Main Authors: Wu, Jia-Ying, Chen, Yu-Wen
• Format: Article
• Language: English
• Subjects: Anatase; Catalysis; Catalytic activity; Chemistry; Chemistry and Materials Science; Conduction bands; Electron states; Film thickness; Glass substrates; Hydrogen peroxide; Inorganic Chemistry; Light; Methylene blue; Oxidation; Photocatalysis; Photodegradation; Physical Chemistry; Sol-gel processes; Surface structure; Synthesis; Thin films; Titanium dioxide; Tungsten oxides; Ultraviolet radiation
• ISSN: 0922-6168; 1568-5675
• DOI: 10.1007/s11164-020-04225-5

A series of WO 3 -modified TiO 2 sols with various WO 3 contents were synthesized by peroxo sol–gel method using H 2 O 2 as the agent. The as-synthesized WO 3 -TiO 2 sols were light yellow in color. The maximum amount of WO 3 which could be incorporated into the TiO 2 sol was 4 wt.%. The pH values of the as-prepared sols were near neutral. These sols were very stable even after 2 years in stock. The sols were used to coat on glass substrate. The XRD patterns and the SAED patterns indicated that the phase of TiO 2 was anatase. There were no characteristic XRD peaks of WO 3 in the WO 3 -modified TiO 2 sol, possibly due to low WO 3 loading. The particles were rhombus shaped with the major axis and minor axis of 30–77 nm and 15–31 nm, respectively. WO 3 was incorporated into the surface structure of TiO 2 and modified the electronic state of Ti. The film coated onto glass substrate was very uniform, and the film thickness was ~ 160 nm. The XPS results exhibited that W existed as 5 + and 6 + oxidation states and Ti existed in Ti 3+ and Ti 4+ . These four chemical states play a role of gathering the photogenerated holes and capturing the photogenerated electrons in the lower conduction band of WO 3 , respectively. This can effectively enhance the separation rate of photogenerated electron–hole pairs and increase the photoactivity. WO 3 /TiO 2 samples had high photocatalytic activity under UV light illumination to degrade methylene blue, because it had high OH and O 2− group contents.