Preparation and photoactivity of samarium loaded anatase, brookite and rutile catalysts

Pure and samarium loaded anatase, brookite and rutile nanopowders were synthesized by thermohydrolysis of TiCl4. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (SSA) determination, UV–vis diffuse reflectance spectroscopy (DRS), atomic force microscopy (AFM), contact angle (CA) measurements and photoluminescence (PL) spectroscopy. The photocatalytic activity of pure and Sm-loaded TiO2 polymorphs was investigated by employing the photodegradation of 4-nitrophenol as probe reaction in a liquid-solid system. Loading with Sm resulted in an improvement of the photoreactivity of the three TiO2 polymorphs. The beneficial effect was explained by an increased separation efficiency of the photogenerated electron–hole pairs. Thin films were obtained by dip coating from water dispersions of the bare and loaded samples. The addition of samarium caused a reduction of the contact angle of the films. A nearly superhydrophilic property was exhibited by the Sm-loaded brookite film.

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► Pure and samarium loaded anatase, brookite and rutile nanopowders were synthesized by thermohydrolysis of TiCl4.
► The beneficial effect of samarium on the photodegradation of 4-nitrophenol was attributed to an increased separation efficiency of the photogenerated electron–hole pairs.
► The presence of samarium reduced the intensity of the photoluminescence spectra obtained for the bare TiO2 phases.
► All films revealed low contact angles and in particular, the surface of the Sm-loaded brookite appeared highly hydrophilic.