Effect of fluoric acid concentration on the structural, optical, and photocatalytic properties of TiO2 thin films

[Display omitted] •Fabrication of fluorine (F) doped TiO2 thin films via the sol–gel dip-coating technique.•Effect of doping concentration on the structural, optical, and photocatalytic properties of TiO2 thin films.•Shift in absorption edge toward the higher energy side.•Photocatalytic degradation of methylene blue dye under UV-light irradiation. In this work, we have successfully fabricated bare titanium oxide (TiO2) and fluorine (F) doped TiO2 thin films via the sol–gel dip-coating technique on the soda lime glass substrates. The effect of hydrofluoric acid (HF) concentration on the structural, optical, and photocatalytic properties of TiO2 thin films is investigated. The films are characterized by the X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), atomic force microscopy, and UV–visible spectrophotometer. The XRD patterns show the presence of highly crystalline anatase phase TiO2. The SEM images reveal some cracked surfaces, while the EDX reveals the absence of fluorine in all samples. The AFM images exhibit a decrease in roughness with the increase in HF concentration. UV–visible spectrometry reveals high transparency in the visible region (about 85%) and the shift in absorption edge toward the higher energy side. To evaluate the photocatalytic performance of the photocatalysts, methylene blue (MB) dye is chosen as a model pollutant. The photocatalytic test shows a decrease in the degradation rate of MB with the increase in HF concentration in the solution. This work will trigger the development of highly efficient acid-modified photocatalysts for environmental remediation.