ZnO微纳米材料及其复合结构的可控合成和性质研究

发布时间：2018-04-13 23:41

本文选题：ZnO + 复合物　；参考：《济南大学》2017年硕士论文

【摘要】：本论文采用水热及溶剂热法,利用不同的表面活性剂控制合成了不同形貌的Zn O微纳米材料,主要包括纳米棒、蝴蝶花、介晶微球等,探究了不同微结构的形成机理。在此基础上,本文进一步研究了在不引入外加还原剂的条件下,通过简单搅拌和超声化学法制备了ZnO/Au复合物,并探索了上述条件下Au3+还原为Au0的机理。对于合成的ZnO及ZnO/Au复合结构进行了光催化降解有机染料的性能研究,并讨论了其光催化机理。此外,基于金属有机框架结构(MOF)的广泛应用,本文以此为前驱体制备了分级ZnO/NiO复合材料并研究其超级电容器的性能。本文的具体研究内容如下:1.蝴蝶状ZnO微纳结构的制备以及利用其自还原能力合成ZnO/Au复合物,该复合物表现出增强的光催化活性。以酒石酸作为表面活性剂,采用水热法和后续的煅烧过程,制备得到形貌各异的ZnO微纳米结构,特别是形貌新颖的蝴蝶状ZnO结构。蝴蝶状ZnO结构的形成机理解释为:在纳米颗粒与重建纳米片之间静电相互作用的诱导下,晶体的成核-生长-自组装过程。在蝴蝶状Zn O表面沉积Au纳米颗粒的过程中没有引入外加还原剂,仅仅通过室温搅拌含有HAuCl4·4H2O的ZnO溶液即可获得ZnO/Au复合物。研究表明:低温煅烧制备ZnO的过程中,ZnO表面的酒石酸分子结晶成为晶体,使得所得样品对Au3+表现出还原性。光催化研究结果显示:ZnO-Au复合物比纯的ZnO样品具有明显增强的光催化活性。2.采用超声化学法在ZnO纳米棒表面原位生长Au纳米颗粒,所得复合物表现出优异的光催化能力。超声体系中不添加任何外加还原剂,在ZnO纳米棒表面实现Au的原位沉积,主要原因是:在超声处理过程中,体系中会产生具有还原性的H原子和自由电子。所得的Au/ZnO异质结在光催化降解过程中表现出优异的光催化活性。特别地,当Au的理论负载量达到4%时,Au/ZnO复合物可以在12 min内完全降解RhB染料。光催化活性增强的原因是复合物中Au可以作为电子捕获剂,加强光生电子-空穴的分离。上述Au/ZnO复合物可以循环应用5次而没有明显的活性衰弱,表明该催化剂具有较好的循环稳定性。此外,CO氧化的研究结果表明:Au的引入极大地增强了ZnO材料的催化活性,主要原因是复合物中Au纳米颗粒可以为催化CO过程提供更多的反应活性位点。3.纳米片基线团状ZnO微球的制备及光催化应用研究。以酒石酸作为结构导向剂,采用水热法合成了由ZnO纳米片组装而成的线团状Zn O介晶。实验研究表明六亚甲基四胺(HMT)的浓度对ZnO产物的尺寸分布及纳米片的堆叠程度起到非常重要的影响。结合系统时间依赖实验的结果,可以推测纳米片基ZnO介晶的形成原因可能是纳米片间偶极相互作用和预形成内核产生的电场作用的协同效应。在不同HMT浓度下制备所得样品的光催化研究结果表明:产物的暗处理吸附能力和光降解能力随HMT浓度的增加而增强,可能的原因是ZnO样品比表面积的增加促进了光生载流子在催化剂和染料分子之间的迁移。4.MOF驱动合成分级ZnO/NiO微结构及超级电容器性质研究。以对苯二甲酸作为有机连接剂,采用溶剂热法和随后N2/O2气氛下的煅烧过程合成纳米片基分级ZnO/NiO微米结构。实验探究表明:Zn~(2+)与Ni~(2+)的摩尔比对产物的微观结构和超级电容器性能均有重要的影响。特别地,当Zn~(2+)和Ni~(2+)的摩尔比分别控制为1:2和1:1时,我们可以分别获得由纳米片组装而成的分级ZnO/NiO中空微球和微米花。当样品用作超级电容器的电极时,相比于中空微球,花状ZnO/NiO表现出更大的比电容和更高的比容量。在电流密度为1 A g-1时,所得微米花的比电容可以达到435.1 F g-1。该微米花状复合物表现出优异的电化学性能主要是因为该微结构为具有更小的本征电阻和电荷迁移阻抗。
[Abstract]:This paper adopts the hydrothermal and solvothermal method by controlling the different morphologies of Zn synthesis of O micro nano materials of different surfactants, including nanorods, butterfly, mesomorphous microspheres, explores different microstructure formation mechanism. On this basis, this paper further studies without introducing external reducing agent under the condition, through simple stirring and ultrasonic chemical preparation of ZnO/Au composites, and explores the conditions for reducing Au3+ Au0 and ZnO/Au ZnO. The mechanism for the synthesis of composite structure is studied the performance of photocatalytic degradation of organic dye, the photocatalytic mechanism was discussed. In addition, metal organic frameworks (based on MOF) has been widely used, based on the performance of a precursor for the preparation of graded ZnO/NiO composites and study the supercapacitor. The specific contents of this paper are as follows: 1. butterfly shaped ZnO micro nano structure and preparation Use the reduction ability of synthesis of ZnO/Au complexes, the complexes exhibited enhanced photocatalytic activity. Using tartaric acid as surfactant by hydrothermal method and subsequent calcination process, prepared with various morphologies ZnO micro nano structure, especially the structure and morphology of butterfly shaped ZnO novel butterfly shaped ZnO structure. The formation mechanism is explained as follows: in between nanoparticles and nano film induced reconstruction of electrostatic interactions, crystal nucleation and growth and self-assembly process. Without introducing external reducing agent in the process of butterfly shaped Zn O Au surface deposition of nanoparticles, only by stirring at room temperature, ZnO solution containing HAuCl4 to 4H2O ZnO/Au complex was obtained. The results show that: the low temperature calcination process of preparing ZnO, tartaric acid molecules on the surface of ZnO crystal as crystal, the samples showed a reduction of Au3+. The photocatalytic results show that the ZnO-Au composite With the photocatalytic activity of.2. was significantly enhanced by ultrasonic chemical method of Au nanoparticles in the in situ growth of ZnO nanorods than pure ZnO samples, the composites show excellent photocatalytic ability. The ultrasonic system does not add any external reducing agent, in situ deposition of Au ZnO nanorods, the main reason is: the ultrasonic treatment process, system will produce a reduction of H atoms and free electrons. The Au/ZnO heterojunction exhibited excellent photocatalytic activity in photocatalytic degradation process. Especially, when the theory of Au load reached 4%, Au/ZnO complexes can be completely degraded within 12 min RhB dye. The enhanced photocatalytic activity of compound Au can be used as electron capture agent, strengthen the separation of photoinduced electron hole. The Au/ZnO complex can be recycled 5 times without application of activity weakened obviously, show that the The catalyst has good cycle stability. In addition, the research of CO oxidation results show that the addition of Au greatly enhanced the catalytic activity of ZnO materials, the main reason is the preparation and photocatalytic application of Au nano particle composites can provide more reactive sites of nano.3. baseline ball like ZnO microspheres as catalyst for CO process. Using tartaric acid as a structure directing agent were synthesized by hydrothermal method by ZnO nanosheets assembled Zn O coil like mesomorphous. Experimental research shows that six of four methylene amine (HMT) concentration on ZnO product size distribution and nano sheet stack level play a very important influence binding. Time dependent experimental results, the formation of reasons to suspect that ZnO nanosheet based dielectric crystal may be a synergistic effect between Nano dipole interaction and pre forming electric field generated by the kernel. Prepared under different HMT concentrations The results of photocatalytic samples show that the product of the dark adsorption ability and photocatalytic ability increases with the increase of HMT concentration, the possible reason is that ZnO promotes the migration of.4.MOF samples of photogenerated carriers between catalyst and dye molecules driven synthesis of hierarchical ZnO/NiO microstructures and properties of super capacitor on the increase of specific surface area. Using terephthalic acid as organic linkers by solvothermal method and then N2/O2 atmosphere calcination process of synthesis of nano film grade ZnO/NiO micron structure. The experimental research shows: Zn~ (2+) and Ni~ (2+) have an important effect on the microstructure of the molar ratio of products and super capacitor properties were. Especially, when Zn~ (2+) and Ni~ (2+) molar ratio respectively control for 1:2 and 1:1, we can respectively obtain assembled by nanoplates grade ZnO/NiO hollow microspheres and microflowers. As the sample with super capacitor The electrode, compared with hollow microspheres, flower like ZnO/NiO showed greater capacitance and higher capacity. At a current density of 1 A g-1, the microflowers capacitance can reach 435.1 F g-1. the micron flower complexes exhibit excellent electrochemical performance is mainly due to the micro structure has smaller intrinsic resistance and charge transfer impedance.

【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33;TM53

【参考文献】