title: Tuning the surface structure of nitrogen-doped TiO2 nanofibres--an effective method to enhance photocatalytic activities of visible-light-driven green synthesis and degradation.
abstract: Nitrogen-doped TiO2 nanofibres of anatase and TiO2(B) phases were synthesised by a reaction between titanate nanofibres of a layered structure and gaseous NH3 at 400-700 °C, following a different mechanism than that for the direct nitrogen doping from TiO2. The surface of the N-doped TiO2 nanofibres can be tuned by facial calcination in air to remove the surface-bonded N species, whereas the core remains N doped. N-Doped TiO2 nanofibres, only after calcination in air, became effective photocatalysts for the decomposition of sulforhodamine B under visible-light irradiation. The surface-oxidised surface layer was proven to be very effective for organic molecule adsorption, and the activation of oxygen molecules, whereas the remaining N-doped interior of the fibres strongly absorbed visible light, resulting in the generation of electrons and holes. The N-doped nanofibres were also used as supports of gold nanoparticle (Au NP) photocatalysts for visible-light-driven hydroamination of phenylacetylene with aniline. Phenylacetylene was activated on the N-doped surface of the nanofibres and aniline on the Au NPs. The Au NPs adsorbed on N-doped TiO2(B) nanofibres exhibited much better conversion (80 % of phenylacetylene) than when adsorbed on undoped fibres (46 %) at 40 °C and 95 % of the product is the desired imine. The surface N species can prevent the adsorption of O2 that is unfavourable for the hydroamination reaction, and thus, improve the photocatalytic activity. Removal of the surface N species resulted in a sharp decrease of the photocatalytic activity. These photocatalysts are feasible for practical applications, because they can be easily dispersed into solution and separated from a liquid by filtration, sedimentation or centrifugation due to their fibril morphology.
authors: School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Qld 4001, Australia.
authors: Zhanfeng
authors: Z
authors: Zheng
authors: Jian
authors: J
authors: Zhao
authors: Yong
authors: Y
authors: Yuan
authors: Hongwei
authors: H
authors: Liu
authors: Dongjiang
authors: D
authors: Yang
authors: Sarina
authors: S
authors: Sarina
authors: Hongjie
authors: H
authors: Zhang
authors: Eric R
authors: ER
authors: Waclawika
authors: Huaiyong
authors: H
authors: Zhu