Studies on the Photochemical Reactions with Nanosized Inorganic Oxides

TiO2 is widely used in different catalytic reactions. The current work investigates the photocatalytic oxidation of MO, RB, TB and BG under UV/Visible light and different nano-sized transition metal molybdate (M = Ni, Cu, Zn) incorporated titanium dioxide/bismuth titanate (MxMoxTi1-xO6/NMBT/CMBT), NixCr1-x MoxP1-xO4 and Fe2O3/TiO2 photocatalysts. All these compounds are synthesized by chemical solution decomposition (CSD) or precursor method, except Fe2O3/TiO2 alloy. The Fe2O3/TiO2 mixed oxides is synthesized by mechanochemical method. The mechanism for oxidation of different organic dyes are following. This is probably due to generation of electron and hole through transformation of Ni(II) to Ni(III) and Fe(III) to Fe(II) ion, where electron resides in conduction band and hole is captured forming Ni3+/ Fe2+, which efficiently reacts with intermediates of dye molecules and decolorized the dyes. However, NMT , CMT, NMBT and Fe2O3/TiO2 semiconductors have smaller band gap energy (Eg = 2.66, 3.03,2.81, 2.26 eV), and high surface area (SBET;149, 101, 71.04, 58.5 m2/g) compared to TiO2. Among these catalysts NMT have smaller particle size about 15nm measured from TEM.