Synthesis Of ZnO-Based Composite Materials And Investigation On Their Visible-Light Photocatalytic Properties

Binary compound photocatalysts, which are formed by coupling narrow-band-gap semiconductor with wide-band-gap ZnO semiconductor, can not only effectively restrain photogenerated electron-hole pair recombination and make full use of solar energy, which could solve increasingly serious environmental pollution problem, but also ease the serious shortage of energy. Therefore, it is of great importance to prepare ZnO-based compound semiconductor photocatalysts and investigate their visible-light photocatalytic performance. Coupling with ZnO semiconductor, In2O3that is a kind of ideal sensitized materials could form heterojunction which possess a wide range of light absorption. ZnSe is also a kind of narrow-band-gap semiconductor, which possesses large exciton binding energy (21meV), and its valence and conduction band are relatively staggered to those of ZnO, which contribute to the production of diffusion potential that is advantageous to the separation of photogenerated electron-hole pairs. Based on their advantages, we successfully prepared ZnO/In2O3and ZnO/ZnSe composite photocatalysts by hydrothermal method. These catalysts were characterized by XRD, SEM, TEM, XPS and PL measurements, and rhodamine B (RhB) and methylene blue (MB) solution were regarded as the goal solutions to study the photocatalytic performance of the ZnO/In2O3and ZnO/ZnSe compound semiconductor photocatalysts and discuss their growth mechanism further. The main research conclusions are as follows: (1) ZnO nanospheres were prepared successfully with zinc acetate and triethanolamine (TEA) as precursors by ultrasonic-assisted hydrothermal method. The morphology and structure of as-prepared ZnO nanospheres were characterized, which made preparation for the next step.(2) Regared Zn(CH3COO)2, Zn(NO3)2, In(NO3)2,TEA and NH3·H2O as precursors, ZnO/In2O3heterojunction photocatalysts with different morphology were synthesized by hydrothermal method. The photocatalytic performance of pure ZnO, pure In2O3and ZnO/In2O3photocatalytsts with different morphology were characterized, and the optical properties of ZnO/In2O3photocatalystls were tested. The systematic study on the interface, band structure and photocatalytic mechanism of ZnO/In2O3photocatalytsts has been conducted.(3) Regarding the as-prepared ZnO nanospheres as templates, ZnO/ZnSe composite photocatalysts were successfully synthesized by hydrothermal method. Adjusting the volume of the reducer hydrazine hydrate, reaction temperature, reaction time and the amount of selenium source, ZnO/ZnSe nanocomposite of different selenylation degrees were synthesized by the control variate method. Then the morphology, crystal structure and photocatalytic efficiency of the nanocomposite structures have been explored. Moreover, the formation process and photocatalytic mechanism of ZnO/ZnSe nanocomposite structures have been systematically analyzed.