水热法制备ZnO和性能研究
通过对其XRD衍射图、SEM图和光催化降解图的系统实验分析和讨论，得出以下结论：
（1）所有样品衍射峰与ZnO标准卡片（65-3411）上的数值基本吻合，所制得的产物为六角结构的ZnO，空间群为P63mc（186），且没有其他杂质的衍射峰存在。尖锐的衍射峰说明水热法所制备的ZnO粉体的结晶度很高。
（2）添加不同的分散剂，样品的形貌发生了变化。当分散剂为PVP时，所制备的样品为海绵状的结构，颗粒粒径较小，还有团聚的现象，一个大的团聚颗粒表面附着许多小颗粒。当分散剂为CTAB时，所制备的样品为颗粒状，颗粒的分散性较好。不同分散剂的添加，引起ZnO的形貌发生显著变化。
（3）ZnO具有很好的光催化效果。以PVP作分散剂时，水热时间为3h的样品50min降解完全；水热时间为6h的样品90min降解完全；水热时间为9h的样品120min降解完全，由此得出，水热时间比较短时制备的ZnO催化活性比水热时间较长时制备的ZnO催化活性高；以CTAB作分散剂时，水热时间为6h所制备的样品催化活性最好，完全降解只需40min。因此，对于不同的分散剂制备出来的样品，水热时间越短，催化效果不一定越好，ZnO样品的催化效率还受到其他因素的影响。而对于水热温度来说，温度越低，得到的样品催化效果越好。
毕业论文关键词:ZnO粉末，水热法，XRD衍射图，SEM图，光催化
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。