Abstract By hydrothermal method in this paper,using zinc nitrate hexahydrate as solute and water as solvent,sodium hydroxide as mineralizer,PVP and CTAB for dispersing agent to prepare different morphologies of ZnO nano powders。Rhodamine B as the object to discuss the effects of different hydrothermal temperature and hydrothermal time on the photocatalytic properties of ZnO。
The following conclusions are drawn through the experimental analysis and discussion of the XRD diffraction and SEM figure and the effect of Photocatalytic degradation rate。
(1)The diffraction peaks of all samples are in agreement with the numerical values of ZnO standard cards(65-3411)。The obtained product is ZnO with six angular structure,the space group is P63mc(186),and there is no other impurity diffraction peak。The sharp diffraction peak shows that the crystallinity of ZnO powder prepared by hydrothermal method is very high。
(2)Add different dispersing agents, the morphology of the samples changed。 When the dispersant is PVP,the prepared sample is spongy structure,the particle size is small,as well as the phenomenon of agglomeration,a large aggregated particles attached to the surface of many small particles。When the dispersant was CTAB,the sample prepared was granular and the dispersion of the particles was better。The addition of different dispersing agents caused significant changes in the morphology of ZnO,which would have a certain effect on the performance of ZnO photocatalysis。
(3)ZnO has a very good photocatalytic effect。When PVP was used as dispersing agent,the hydrothermal time was 3h,the sample 50min was completely degraded;the hydrothermal time was 6h,the sample 90min was completely degraded;and the hydrothermal time was 9h,the 120min was completely degraded。It indicate that hydrothermal time low when compared with the prepared ZnO photocatalytic activity than higher hydrothermal time of ZnO catalytic activity high。Using CTAB as dispersant, hydrothermal time is 6h of samples prepared by catalytic activity best and it only need 40min。As a result,the hydrothermal time is shorter and the catalytic effect is not better than that of the samples prepared by different dispersing agents。The catalytic efficiency of ZnO is also affected by other factors。And for the hydrothermal temperature,the lower the temperature,the better the catalytic effect of the samples obtained。