| Nano-crystalline ZnO films were prepared onto glass substrates using sol-gel method combined with dip-coating technique and then annealed.The heat treatment temperature and duration were varied,and the correlation between the heat treatment and photoactivities was investigated.The structure variations were traced and investigated by their optical properties and their relations with the photocatalylic abilities were studied.An increase in the applied heat treatment,either by increasing the temperature or increasing the heat treatment duration,led to the increase in decomposition ratio of organics in precursor and the particle size.The films treated with high temperature for short time(HTST)proposed in this paper performed better. It is because HTST process can provide not only purity and small crystalline but also widen crystal size distribution.Corrosion during the catalyzing process would shorten the lifetime of the photocatalysts as well as cause the metal ions pollution.This paper focused on the corrosion of this type.Nano-crytalline ZnO film was prepared by sol-gel method and the film was modified with silver by photo-reduction of AgNO3 in solution.Methyl orange were used as pollutant.The mechanism was studied and the correlation between with solution components including pH and salinity was discussed.The results showed the corrosion was mainly caused by dark corrosion and it was the particles which released into the solution rather than the ions themselves.Its rate was pH and salinity dependent with the lowest value near pH=9 and no salinity.Samples modified with silver had much lower corrosion speed than that of the original.2 types of nickel modified ZnO thin films on soda glass substrates were prepared by sol-gel dip coating process.There are Ni-doped ZnO,ZnO/NiO/(glass)bilayer. Effects of modifying on the structural and optical properties of ZnO films were investigated by XRD,optical transmittance,SEM and PL spectroscopy.It reveals that doping of Ni ions formed the substitution in the ZnO lattice,while in the bilayer structure Ni existed in free NiO.Both of them slightly change the band structures.The photo-catalytic activity was characterized by photo degradation of aqueous methyl orange under UV radiation.It is found that,the Ni dopant decreased the photo-catalytic activity of ZnO films,but the activity of ZnO/NiO/(glass)was increased.The mechanism can be attributed to these processes:(1)Ni doping formed the substitution defects in lattice and reduces the oxygen vacancies.(2) ZnO/NiO/(glass)bilayer structure enhancing the electron-hole pair separation and inhibiting their recombination by adsorbing the charges in the p-n junction.A novel Ag/ZnO/NiO film was deposited on glass slide using a sol-gel method combined with photo-induced reduction technique.SEM,PL,XRD and UV-vis were applied to observe the surface morphology,analyze the composition and show their optical properties,The results of XRD and UV-vis spectroscopy showed that there was a hetero-junction structure composed of NiO and ZnO;FESEM figures implied that the layers of silver and zinc oxide were formed and covered incompletely;PL spectra demonstrated that the photoluminescence intensity of the tri-layer film was weaker than those of bilayer or monolayer film.Photocatalyze test in which methyl orange and low pressure mercury lamp were served as model pollutant and irritation source separately showed that the trilayer film Ag/ZnO/NiO was possessed of a much more strong activity than the monolayer film.Since the outer layers can not covered inner ones,there were many micro-electrodes on the surface of the film. Micro-electrodes make it easier for exitons to separate and result in the higher activity.
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