High-efficiency TiO2/ZnO nanocomposites photocatalysts by sol–gel and hydrothermal methods

• Published in: Journal of sol-gel science and technology 2021-07, Vol.99 (1), p.92-100
• Main Authors: Bai, Ningna, Liu, Xiangchun, Li, Zhengguang, Ke, Xinyu, Zhang, Kai, Wu, Qi
• Format: Article
• Language: English
• Subjects: Ceramics; Chemistry and Materials Science; colloids; Composites; Decoloring; Efficiency; etc.; fibers; Glass; Heterojunctions; Inorganic Chemistry; Kinetic equations; Materials Science; Methylene blue; Nanocomposites; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper: Nano-structured materials (particles; Photocatalysis; Photocatalysts; Photodegradation; Sol-gel processes; Titanium dioxide; Zinc oxide
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-021-05552-8

TiO 2 /ZnO nanocomposites with ratio of Ti/Zn of 1:0, 1:1, 2:1, 3:1 and 0:1 was synthesized by sol–gel and hydrothermal methods. The performance and the photocatalytic of the nanocomposities mechanism were studied by X-ray diffractometer (XRD), Fourier transformed infrared (FT-IR), Brunauer–Emmett–Teller method (BET), Transmission Electron Microscopy (TEM), High-Resolution Transmission Electron Microscope (HRTEM) and UV–visible diffuse reflectance spectra (UV-Vis), respectively. The results showed that TiO 2 /ZnO nanocomposites successfully prepared at different Ti/Zn rations. HRTEM results clearly heterojunction structure, and it can reduce the band gap width of the composite and improve the optical absorption intensity. Besides, the degradation rate of methylene blue (MB) of TiO 2 /ZnO nanocomposites with a Ti/Zn ratio of 2:1 was close to 100% at 80 min, which was better than the other four samples. The photocatalytic degradation reaction confirmed to the first-order kinetic equation. The kinetic constant of TiO 2 /ZnO nanocomposites with a ratio of 2:1 is 0.03748 min −1 , which is 2.8 times of pure ZnO and 4.8 times of pure TiO 2 , respectively. In addition, the major active species of the photocatalytic reaction are •OH and h + through activity capture experiments. The improvement of the catalytic performance of TiO 2 /ZnO nanocomposites is mainly due to the ability to separate holes and electrons. Highlights High efficiency TiO 2 /ZnO photocatalysts are prepared by sol–gel and hydrothermal technology. Increase in catalytic efficiency due to the separation efficiency of electrons and holes. MB decolorization is not directly related to adsorption. The degradation of MB is a first order degradation kinetics. The major reactive species for photodegradation is the •OH.