Photocatalytic Degradation of Methylene Blue on Multilayer TiO2 Coatings Elaborated by the Sol-gel Spin-Coating Method

In this work, TiO2 thin films consisting of 1, 2, and 3 layers were prepared using the sol-gel spin-coating method with a spin speed of 1020 rpm and a spin time of 43 s. The analysis of the films by XRD and FTIR revealed that they exhibited crystallization in the form of anatase, with a crystal size of approximately 29.25 nm for all three layers. The photocatalytic activity of the TiO2 thin films and their ability to decompose methylene blue (MB) in water were investigated. The results demonstrated that after 4.5 h, the degradation of MB reached 72%, 82%, and 98% for 1, 2, and 3 spin-coating cycles, respectively. This was confirmed by the MB absorption spectra, the increase in the degradation rate constant (k(1,deg)), and the decrease in E-g as a function of the number of spin-coating cycles. Additionally, a photodegradation mechanism of MB was reported and further supported by an energy diagram constructed using the DFT method.

Automated summary

In this study, TiO2 thin films with different layers were prepared using the sol-gel spin-coating method. The films showed good photocatalytic activity and ability to degrade methylene blue. The degradation efficiency increased with the number of spin-coating cycles.