Enhanced photocatalytic degradation of methylene blue using DEA-modified TiO₂ thin films

Abstract In this study, TiO 2 thin films were successfully fabricated on silicon substrates using the spin coating method, with varying volumes of diethanolamine (DEA) added to the precursor solution. The objective was to evaluate the effect of DEA concentration on the structural and photocatalytic properties of the films for methylene blue (MB) wastewater treatment. X-ray diffraction analysis confirmed the formation of the anatase phase in all samples, which is well-known for its high photocatalytic activity. Photocatalytic performance was assessed through the degradation of MB under UV irradiation, with photolysis control confirming negligible dye degradation in the absence of the films. The results demonstrated that the film with optimized DEA content achieved the highest degradation efficiency of 80.03%. Reusability tests showed decreasing performance over repeated cycles (80.03%, 54.74%, 39.60%, 39.77%, and 39.93%), indicating surface fouling and active site loss. This study highlights the influence of DEA on film formation and photocatalytic behavior, and suggests the potential of spin-coated TiO 2 thin films for effective application in organic wastewater treatment.