Controlled Preparation And Photocatalytic Performance Of Micro-nano Zinc Oxide And Tin Materials

Micro-nano materials because of its unique physical and chemical properties in catalysis,sensing,optoelectronics has a wide range of applications,Therefore,preparation of novel metal oxide nanomaterials,controlling their morphology,size and dimension,and studying their growth mechanisms have become the hot topics in this field.In this dissertation,novel micro-nano materials were prepared by using micro-nano materials of semiconductor metal oxides(ZnO and SnO2)and their doped micro-nano materials,furture the possible formation mechanism was discussed.The application of these three kinds of micro-nano materials as photocatalysts to degrade organic pollutants was studied.(1)The hierarchical flower-like Zn-doped SnO2(FLZn-SnO2)architectures composed of curved sheets are synthesized by a hydrothermal method at 180℃ for 8 h.We can obtain the morphological evolution of FLZn-Sn02 by a series of control experiments.Based on the nucleation and self-assembly process,a possible formation mechanism is proposed.Zinc nitrate and Sodium oxalate in the control experiments affected the morphology of FLZn-SnO2.Moreover,aqueous photocatalytic activity tests with RhB revealed that FLZn-SnO2 architectures possesses an excellent photocatalytic performance.With the addition of appropriate amount of zinc nitrate,the photodegradation rate of RhB with tin dioxide increased from 72.7%to 88.7%within 60 min.It has been found that the introduction of zinc ions can inhibit the rapid recombination of photogenerated electron-hole pairs,resulting in greatly enhanced photocatalytic activity.(2)The novel hierarchical flower-like SnO2 nanostructures with the diameter of about 1～2 μm,which are composed of regular-shaped nanosheets,are synthesized with a solvothermal method in the presence of 0.183 g of sodium citrate at 160 ℃ for 6 h.Based on the nucleation and self-assembly process,possible formation process of the new hierarchical flower-like nanostructures can be presented.The effects of sodium citrate and time on the product are also studied.Moreover,the obtained SnO2 nanostructures exhibit higher photocatalytic activity towards the degradation of RhB under visible-light irradiation,up to 91.7%within 60 min.In short,this study provides an effective way to control and design the shape of Sn02.These nanosheet-assembled SnO2 has excellent photocatalytic properties and can be further used for other applications such as gas sensing and electrocatalysis.(3)The novel lower-shaped ZnO nanomaterial have been successfully prepared via a facile hydrothermal metod.The product was characterized and analyzed by XRD,SEM,DRS and XPS.The photocatalytic activity of ZnO was evaluated by photodegradation of rhodamine B(RhB)under simulated ultraviolet light.We can obtain the morphological evolution of the ZnO by a series of time-depended tests have been listed.A possible growth mechanism is proposed as nucleation and growth of small primary nanoparticles through an oriented attachment mechanism.After 120 minutes of UV irradiation,the photodegradation rate of ZnO to RhB aqueous solution reached 93.6%,showing good photocatalytic performance.