Sol–Gel Synthesis and Characterization of CeO _x –SiO ₂ –TiO ₂ Thin Films

Abstract

CeO x –SiO 2 –TiO 2 (CST) thin films deposited on glass are successfully prepared by sol–gel dip‐coating method and characterized using X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), ultraviolet‐visible (UV‐vis) absorption, and water contact angle measurement techniques. XPS results indicate that Ti exists mainly in the form of Ti 4+ . Ce 4+ and Ce 3+ coexist and Si exists in the form of Si 4+ on the surface of the CST films. The asymmetric O 1 s peaks fitted by Gaussian–Lorentz function are also discussed. AFM analysis reveals that no spherical particles are observed for the CST film due to its smaller particles, and it has lower surface roughness as compared with pure TiO 2 film. The UV‐vis spectra demonstrate that absorption edges for the CST film with Ce/Ti=5% exhibit obvious red shift as compared with pure TiO 2 film. Especially for Si/Ti=10% samples, band gap energy reduces to a minimum of about 2.87 eV. Moreover, CST films have much smaller water contact angle of less than 10°, while the pure TiO 2 film shows a water contact angle of 60°. The Si/Ti=20% samples reach superhydrophilicity with water contact angle of 3° after UV irradiation for 30 min.