Ziya Wang

Enhanced UV-Visible Light Photocatalytic Activity by Constructing Appropriate Heterostructures between Mesopore TiO2 Nanospheres and Sn3O4 Nanoparticles

Novel TiO2/Sn3O4 heterostructure photocatalysts were ingeniously synthesized via a scalable two-step method. The impressive photocatalytic abilities of the TiO2/Sn3O4 sphere nanocomposites were validated by the degradation test of methyl orange and •OH trapping photoluminescence experiments under ultraviolet (UV) and visible light irradiation, respectively. Especially under the visible light, the TiO2/Sn3O4 nanocomposites demonstrated a superb photocatalytic activity, with 81.2% of methyl orange (MO) decomposed at 30 min after irradiation, which greatly exceeded that of the P25 (13.4%), TiO2 (0.5%) and pure Sn3O4 (59.1%) nanostructures. This enhanced photocatalytic performance could be attributed to the mesopore induced by the monodispersed TiO2 cores that supply sufficient surface areas and accessibility to reactant molecules. This exquisite hetero-architecture facilitates extended UV-visible absorption and efficient photoexcited charge carrier separation.

Induction of zinc particles on the morphology and photoluminescent property of globular Zn/ZnO core/shell nanorod heterojunction array architectures

Zn/ZnO metal/semiconductor nanostructures were successfully synthesised by a facile zinc-rich chemistry liquid-phase approach with zinc microspheres as sacrificial templates at ambient temperature. A series of globular Zn/ZnO core/shell structures and hollow microsphere architectures self-assembled by Zn/ZnO nanorod heterojunction arrays were obtained by controlling the amount of zinc particles. The structure, morphology, composition and optical properties of the products have been characterised by X-ray diffraction, scanning electron microscopy, Raman spectroscopy and photoluminescent spectroscopy. A possible growth mechanism of the Zn/ZnO nanostructures has been proposed based on the structural analysis. The growth mechanism of Zn/ZnO hollow microspheres is ascribed to Kirkendall effect. A new strong blue emission at 440 nm and a green emission around 500 nm with an enhancement over one order of magnitude compared with the pure ZnO sample have been observed. These emission bands are attributed to two kinds of mechanisms that have been discussed in detail.

The resonant, near-resonant, and off-resonant plasmon coupling effects for the bonding modes in two types of asymmetric dimer

The resonant, near-resonant, and off-resonant plasmon coupling effects for the bonding modes in asymmetric dimers are illustrated by two types of configuration, one formed by a gold nanoparticle and a TiO2–Ag core–shell nanoparticle and the other formed by two TiO2–Ag core–shell nanoparticles with suitable sizes. The redshift and blueshift behaviours of the coupled bonding modes with decreasing gap are found under longitudinal and transverse polarization of light for these dimers in the resonant situation, respectively. Under the near-resonant situation, the redshift behaviours of the coupled bonding modes still remain under longitudinal polarization, whereas the two separated modes of monomers after coupling under transverse polarization exhibit no obvious peak-shift behaviours, and the one on the lower frequency side shows an apparent attenuation in the strength. Under the off-resonant situation, the redshift behaviours not only occur in the coupled modes under longitudinal polarization, but also occur in two separated modes under transverse polarization.