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An insight toward the photocatalytic activity of S doped 1-D TiO2 nanorods prepared via novel route: As promising platform for environmental leap

   Abu Bakar, Shahzad; Ribeiro, Caue

The photocatalytic applications of the S-doped titanium dioxide (TiO2) are of great importance due to photon-to-carrier conversion ability of S-doping in the energy region below the band gap of pure TiO2. Therefore, 1D (one dimensional) S-doped TiO2 anatase nanorods were synthesized first time by facile, low temperature and template free oxidant peroxide method (OPM). The addition of thiourea as sulfur precursor favored the formation of better crystalline anatase TiO2 and S atoms favorably crystalized the anatase structure. It was found that substitution of Ti4+ by S6+ in the lattice of S doped TiO2 nanorods increased the number of adsorbed active groups (hydroxyl radical) at the surface of catalyst and also gave rise to the visible-light response. The formation of Ti-O-S bond favors the partial transfer of electrons from S to 0 atoms. It helps the electron-deficient S atoms to hold/capture electrons and thus reduce the recombination rate of photogenerated electron-hole pairs. The preferred anatase {1 0 1} facets could also act as beneficiary reservoirs to decrease the recombination probability of electron-hole pairs. Methylene blue (MB) was used as target organic molecule for evolution of photocatalytic activity by photocatalytic oxidation reaction under visible-light. The mineralization products of MB were detected using High Performance Liquid Chromatography (HPLC) and GC/MS spectroscopy that gave the pattern of possible degraded fragments from the mineralization of MB. The role of active species in the degradation process was identified with the help of Mott-Schottky measurement, addition of different scavengers and the band structure obtained from the UV-vis diffuse reflectance spectrum. It was found that holes and hydroxyl radicals played major role in the photo-degradation of MB. The fundamental mechanism for enhanced photocatalytic performance of S doped TiO2 nanorods was discussed in detail and attributed to the S doping and morphology engineering that may improve the electron-hole pair separation efficiency for enhanced photocatalytic performance under visible-light irradiation. This work may provide an insight into the synthesis of S doped TiO2 photocatalysts that showed good stability after four cycles and have great potential for environmental purification of organic pollutants. (C) 2015 Elsevier B.V. All rights reserved.

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