Zhengshu Wang

Facile synthesis of ZnS-ZnO nanocomposites for enhanced photocatalytic activity

Novel ZnS–ZnO nanocomposites were successfully synthesised via a facile thermal treatment of ZnS microstructure spheres. Microstructure, morphological and photocatalytic activity were fully investigated. X-ray diffraction patterns indicated that the ZnO was successfully decorated on the surface of ZnS. The microstructure of ZnS was transformed into nanocomposites after the formation of ZnO. The value of band gap decreased from 3.37 to 3.00 eV, which enhanced the light utilise efficiency. The ZnS–ZnO nanocomposites exhibited enhanced photocatalytic activity, compared with pristine ZnS. The enhancement of photocatalytic performance was attributed to the increased light absorption and effective separation of photogenerated electrons–holes.

Solution self-assembly of flower-like ZnO nanostructures with nanosheets and their optical properties

A uniform flower-like ZnO materials assembled by nanosheets have been synthesised on a large scale by a facile, cost efficient and room temperature solution route without the assistance of any substrate, template or seed layers. X-ray diffraction and field emission scanning electron microscopy were employed to characterise the phase composition and morphology of the samples, and ultraviolet–visible (UV-vis) diffuse reflectance spectrum and photoluminescence (PL) spectrum were used to analyse the optical properties of the samples. The flower-like ZnO materials with an average diameter of ∼2 μm are composed of interacted nanosheets with an average thickness of ∼5 nm. A reasonable growth mechanism that the formation of this kind of flower-like ZnO structures experienced a two-stage nucleation growth process was discussed. Based on the UV-vis diffuse reflectance spectrum, the band gap of hierarchical flower-like ZnO materials was calculated to be 3·27 eV. The PL spectrum suggests that flower-like ZnO materials only emit UV light and possess good optical properties.