Synergistic effect of Pt-0 and M2+ (Cu2+, Ni2+, Co2+) on photo(electro) catalytic activity of TiO2 nanorod array thin films

M2+ (Cu2+, Ni2+, Co2+) and Pt-0-M2+ loaded TiO2 nanorod film samples were prepared on transparent conducting oxide glass (FTO/F:SnO2). Two step method was used consisting a hydrothermal method to grow TiO2 nanorods on the surface and an ultrasonic-assisted sequential cation adsorption method to modify the nanorods. The samples were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (DRS), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy. The photoelectrochemical properties of the samples were evaluated by linear sweep voltammetry, photocatalytic activities were tested by methylene blue degradation under visible light. M2+-TiO2/FTO samples were compared with Pt-0-M2+-TiO2/FTO samples; the synergistic effect of Pt-0 and M2+ was discussed. Pt-0-Ni2+-TiO2/FTO showed superior photoelectrocatalytic activity with 1.358 mA cm(-2) and 78.3% methylene blue degradation under visible light. Quantum yields were calculated separately as a sign for H-2 generation rate and as a conversion of methylene blue molecule per absorbed light. (C) 2015 Elsevier B.V. All rights reserved

A comparative study for removal of different dyes over M/TiO2 (M = Cu, Ni, Co, Fe, Mn and Cr) photocatalysts under visible light irradiation

The purpose of this work is to design and develop a series of stable and effective TiO2 photocatalysts prepared by a modified precipitation method. In order to improve the photo response of the TiO2 to the visible region, the effect of addition of six successive transition metal elements of fourth period, namely chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu) was studied. Two different types of dyes, methyl orange (MO, azo dye) and methylene blue (MB, thiazine dye group), were used to investigate the influence of structure of dyes on the photocatalytic degradation rates. The results showed that loading titania with 0.3 wt.% of different transition metal elements was found to have significant influences on the crystallographic structure, physical properties and optical absorption properties of titania based catalysts, as well as catalytic activity during dye degradation reactions. The optical reflection edge was obviously shifted to the visible light range with the transition metal additives. The band gap energies of the doped TiO2 samples were considerably narrower than that of plain TiO2. The different activity levels of the catalysts for both dyes clearly show that the photocatalytic activity of samples strongly depended on the metal dopant used. Among all the catalysts, Cu/TiO2 sample exhibited the highest photocatalytic activity under visible light for both of the dyes owing to the low band gap energy and delayed electron-hole recombination. (C) 2015 Elsevier B.V. All rights reserved