Modeling, optimization and characterization of titanium dioxide thin film prepared by the spin-coating method using the experimental design for an application of photocatalytic degradation of methylene blue

Abstract

This work focuses on modeling and optimizing the deposition of a TiO2 film on ITO glass using the spin-coating method and experimental design. The parameters studied include the concentration of the solution, speed and duration of rotation, drying temperatures and time, and calcination temperature and time. Results show that optimal conditions are achieved at 457 g/l concentration, 1020 rpm speed, 43 s duration of rotation, 100 °C drying temperature for 30 s, and 500 °C calcination temperature for 2 h. XRD, FTIR, EDX, and SEM analyses of the TiO2/ITO film indicate crystallization in the anatase phase with a 29.3 nm crystal size and around 80% deposition quality, with good surface adhesion and a thickness of approximately 30 nm. The photocatalytic activity of the thin film for the decomposition of methylene blue (MB) in water was also studied. Results showed a 70% degradation of MB after 4.5 h, which was confirmed by absorption spectra and discoloration of MB. Additionally, the degradation reaction of MB by TiO2 followed the pseudo-first-order, with good agreement between the kinetic study and a high degradation rate constant (k1deg = 0.2919 (h−1)), indicating a rapid process. Finally, a photodegradation mechanism of MB was reported.