Investi Gating On Preparation And Opti Cal Properties Of Nano ZnO Porous Mat Erials

The thesis was based on the two porous materials of film and powder catalysis in the difference of practical application,and the porous structures of ZnO prepared by different templates were investigated respectively.The starting point,is scheme feasible to increase the path of light propagation and improve the utilization of photons by the interaction between porous ZnO and light.Meanwhile,are these ideas reasonable,the element dopingwas introduced to modify the crystal quality and increase the carrier concentration,the introduction of Ag substance was for the inhibition of the recombination of photo-generated carriers by plasmon resonanceeffect.Whether the final test of photocatalytic degradation of methyl orange(MO)can prove the great improvement of optical properties Themain contents are as follows:The ZnO template with porous skeleton structure was prepared by a sol-gel method with a designed mass ratio of Zn source to glucose monohydrate in the precursor.A Na-doped ZnO film was then deposited on the porous template by a chemical vapor deposition(CVD)technique Finally,the Na-doped ZnO porous film was composited with Ag nano-sheets via a photodeposition method.And the effects of template porosity,the Na doping concentration,and the composite with Ag nano-sheets on the optical properties of ZnO crystal were investigated.The optimum template porosity was determined in the sample prepared with the mass ratio of Zn source to glucose monohydrate as 8:1 in precursor according to the effective specific surface area.And the optimum carrier flow rates of Na,Zn,O sources in CVD were 75 sccm,150sccm,130sccm,respectively,in which Na doping increases the intrinsic defect concentration of ZnO.As a nano mirror,the composite with Ag nano-sheets further improved the utilization of light.The sample of Na-doped ZnO porous film composited with Ag nano-sheetsshows a significant increase in absorption spectral strength and catalytic performanceThe polystyrene(PS)nanospheres as templates were prepared by emulsion polymerization method.Theporous ZnO hollow nanospheres were prepared by sol-gel method,and then thereaction site were increased due to the increase of specific surface area.The optimum Al dopant concentration was 3%of that of Zn source,in which the dopantcontributed to the improvement of electron emission center number,and thereby increased the excited electron concentration.The interaction between Ag and ZnO hollow spheres resulted in the plasma resonance effect,which led to the formation of electron guideway and improves the transfer of excited electrons.Finally,the reaction centers were formed on Ag nanoparticles.Compared with the traditional powdercataly sts,the Al doped porous ZnO hollow spheres composited with Ag nano-sheets performed more effective photocatalytic degradation of MO solution.