Adsorption and Photocatalytic Degradation of Methylene Blue on TiO(2) Thin Films Impregnated with Anderson-Evans Al-Polyoxometalates: Experimental and DFT Study

[Image: see text] In this work, we fabricated a TiO(2) thin film, and the same film was modified with an Anderson aluminum polyoxometalate (TiO(2)-AlPOM). Physical–chemical characterization of the catalysts showed a significant change in morphological and optical properties of the TiO(2) thin films after surface modification. We applied the kinetic and isothermal models to the methylene blue (MB) adsorption process on both catalysts. The pseudo-second order model was the best fitting model for the kinetic results; qe (mg/g) was 11.9 for TiO(2) thin films and 14.6 for TiO(2)-AlPOM thin films, and k(2) (g mg(–1) min(–1)) was 16.3 × 10(–2) for TiO(2) thin films and 28.2 × 10(–2) for TiO(2)-AlPOM thin films. Furthermore, the Freundlich model was suitable to describe the isothermal behavior of TiO(2), K(F) (5.42 mg/g), and 1/n (0.312). The kinetics of photocatalytic degradation was fitted using the Langmuir–Hinshelwood model; k(ap) was 7 × 10(–4) min(–1) for TiO(2) and 13 × 10(–4) min(–1) for TiO(2)-AlPOM. The comparative study showed that TiO(2) thin films reach a 19.6% MB degradation under UV irradiation and 9.1% MB adsorption, while the TiO(2)-AlPOM thin films reach a 32.6% MB degradation and 12.2% MB adsorption on their surface. The surface modification improves the morphological, optical, and photocatalytic properties of the thin films. Finally, the DFT study supports all the previously shown results.