Facile Synthesis of TiO<inf>2</inf>/TiSi<inf>2</inf> Composite with Enhanced Visible-Light Photocatalytic Properties

Abstract

TiO2 has attracted intensive attention owning to its nontoxicity, low cost, super-hydrophilicity, long-term chemical stability and high photocatalytic activity. Various synthetic strategies for this important semiconductor have been attempted so far, usually using titanium (Ⅲ/Ⅳ) halide or alkoxide compounds as the titanium source. In this paper, urchin-like TiO2/TiSi2 composite was developed by a facile one-pot hydrothermal method, using TiSi2 and HCl as the Ti precursor and morphology control agent respectively. The hydrothermal reaction was performed by using polytetrafluoroethylene(PTFE)-lined stainless steel autoclave as reactor in an oven and kept at 180 ℃ for 18 h. The as-prepared samples were characterized systematically by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscope (XPS) and UV-visible absorption spectra (UV-vis). Results indicated that the urchin-like TiO2 assembled by nanorods grown on TiSi2 substrate was confirmed to grow along [001] orientation and exhibited uniform size and smooth surfaces. In addition, the tips of TiO2 nanorods presented pyramid tetrahedron shape and could convert to cone shape with increasing the concentration of HCl aqueous solution. Furthermore, compared with pure rutile TiO2, TiO2/TiSi2 composite showed a higher absorption in visible light. Thus, the significant enhanced photodegradation efficiency of the organic pollutants with the TiO2/TiSi2 composite under visible light irradiation was obtained. The photodegradation rates of methyl orange were measured which confirmed the highest performance of the TiO2/TiSi2 composite in comparison to pure rutile TiO2 and TiSi2.