Enhancement of photocatalytic properties of TiO₂ nanoparticles doped with CeO₂ and supported on SiO₂ for phenol degradation

Highlights: • CeO₂-TiO₂/SiO₂ composites were prepared via a facile co-precipitation method. • Introduction of SiO₂ support increases the dispersion of CeO₂-TiO₂. • CeO₂-TiO₂/SiO₂ exhibits an enhanced photocatalytic efficiency for phenol degradation. • Ce³⁺/Ce⁴⁺ pair coexisting in CeO₂ improves electron–hole pairs separation efficiency. - Abstract: A series of CeO₂-TiO₂ and CeO₂-TiO₂/SiO₂ composites were prepared with TiCl₄ and Ce (NO₃)₃·6H₂O as precursors via a facile co-precipitation method. The obtained samples were characterized by various techniques such as X-ray diffraction (XRD), nitrogen adsorption (N₂-BET), Fourier transformation infrared spectrum (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–Vis spectroscopy measurements. The results indicated that TiO₂ doped with CeO₂ and supported on SiO₂ could reduce the crystallite size, inhibit the phase transformation, enhance the thermal stability, and effectively extend the spectral response from UV to visible range. When applied to the phenol photodegradation on a homemade batch reactor with an external cooling jacket, the CeO₂-TiO₂/SiO₂ catalysts exhibited significantly enhanced photodegradation efficiency in comparison with commercial Degussa P25 and CeO₂-TiO₂. The unique catalytic properties of CeO₂-TiO₂/SiO₂ were ascribed to improved electron–hole pairs separation efficiency and formation of more reactive oxygen species owing to the presence of Ce³⁺/Ce⁴⁺, as well as high dispersion of active component of CeO₂-TiO₂ as a result of the introduction of SiO₂ support. Furthermore, the catalysts can be easily recovered from the reaction solution by centrifugation and reused for four cycles without significant loss of activity