【作者】 刘海瑞；

【导师】 贾虎生；

【作者基本信息】 太原理工大学 ， 材料科学与工程， 2013， 博士

【摘要】 21世纪,环境污染和能源危机以严重影响人类生存与社会发展,光催化氧化技术被认为是解决这一难题的最有效的途径之一。光催化技术由于耗能低、易操作、无二次污染等,已成为催化领域中的研究热点之一。ZnO作为一种高效、廉价、无毒、易制备的光催化剂,已受到国内外的广泛关注。本论文针对如何提高ZnO材料的光催化效率,有效利用太阳能以及对一些恶劣环境中的使用,分别制备了二元,三元ZnO基复合光催化剂以及一些InGaN纳米材料,对其结构、形貌、光吸收特性和表面物理化学性质进行了详细的表征,研究了其光催化行为,探讨了光催化效率提高的原因。取得的主要研究结果如下：1.采用微波辅助多元醇方法,制备出Ag纳米颗粒、纳米立方体、纳米线。掌握了添加剂Na2S和PVP的浓度、微波功率、反应时间对Ag纳米产物形貌影响规律。发现Na2S浓度是影响Ag纳米形貌的主要因素,当添加Na2S浓度为0.25mM时,得到的是Ag纳米颗粒；当Na2S浓度增加到0.25-1mM时,可以制备尺寸可控的Ag纳内米立方体；而当Na2S浓度增大到1.5mM时,可得到分布比较均匀的Ag纳米线。通过分析反应过程,建立了Ag纳米产物随着S2-浓度变化的生长模型。2：通过超声辅助方法,在醋酸锌的水溶液中添加TEA,成功制备了不同粒径的ZnO微米球。对不同反应时间所制备的ZnO相关产物的形貌、结构、光学及光催化性能进行了表征,结果表明：随着反应时间的增加,反应产物由层基醋酸锌(LABZ:Zn5(OH)8Ac2·2H2O)纳米片自组装而成的花状结构逐渐分解为六方纤锌矿结构的ZnO纳米球,纳米ZnO球自组装逐渐变成粒径较大的ZnO微米球。随着反应时间的增加,ZnO球的紫外可见吸收光谱吸收峰的峰位从422nm蓝移到364nm,而且吸收峰强逐渐增强；而PL发射峰则不随反应时间的增加而变化,都在364nm,只是峰强逐渐增强。随着ZnO粒径的增加,ZnO微米球对罗丹明B的催化效率依次减小,这主要是由于ZnO微米球粒径的增加,使比表面积逐渐减小,导致在催化过程中和有机染料的接触面减小,降低了催化效率。3：通过在醋酸锌和TEA的混合水溶液中添加Ag纳米线,然后在超声辐射的条件下,合成了蠕虫状的Ag/ZnO异质结。通过改变Ag纳米线的添加量来控制合成的异质结中的Ag含量。比较制得的Ag/ZnO的形貌、晶体结构、光学和光催化性能,结果表明：面心立方结构的Ag纳米线和六方纤锌矿结构的ZnO构成的Ag/ZnO异质结,随着Ag含量的增加,蠕虫状异质结的量不断增加,团聚的颗粒物质减少,而且,Ag/ZnO异质结的的荧光发光峰位于370nm处,光强先减小后增大。Ag/ZnO异质结对若丹明B的光催化效率随Ag含量先增大后减小,在Ag含量为2.8%时,Ag/ZnO异质结的光催化效率达到最大。4：通过选择性地在硝酸铟的水合三乙醇胺(TEA)混合溶液中添加醋酸锌和Ag纳米线乙醇溶液,利用水热法和退火处理制得到了In2O3/ZnO/Ag三元异质结。通过对产物的形貌、晶体结构、可见光催化性能进行了表征,结果表明：In2O3/ZnO/Ag三元异质结是以面心立方结构的Ag纳米线为轴、由六方纤锌矿结构ZnO和体心立方结构In2O3包覆形成。在可见光催化作用下,对罗丹明B的降解反应活性依次为：Ag<ZnO/Ag<In2O3/Ag<In2O3/ZnO<In2O3/ZnO/Ag, In2O3/ZnO/Ag三元异质结表现出最强的可见光催化活性。随着Ag含量的增加,In2O3/ZnO/Ag三元异质结的荧光发光峰在370nm处和540nm的光强先减小后增大,对若丹明B的光催化效率却是先增大后减小,在Ag含量为3.8%时,制备的In2O3/ZnO/Ag三元异质结的光催化效率达到最大值。5：采用简单的APCVD法,成功制备了InGaN纳米材料。在Au催化作用下,InxGa1-xN形貌随In含量的增加由花状结构转变成塔形结构,晶体结构均为六方纤锌矿,其发光性能有所增强,而且同时出现了GaN和InxGa1-xN (x>0)两个本征峰。塔形结构的InGaN对有机染料酸性橙的降解效果最好,在pH值为3时,降解效率可达到95%。更多还原

【Abstract】 In the21st century, the globle environmental pollution and energy crisis is becoming more and more serious, and they have been serious affected the survival and development to human being. Photocatalytic oxidation technology is considered to be one of the most effective ways to solve this difficult problem. Photocatalytic technology has become an international hot spot in the field of catalysis due to low consumption easy operation, no secondary pollution, etc. ZnO, as a kind of low efficient non-toxic easy preparation of photocatalyst, has received extensive attention in the world. In this thesis, we focus on how to improve photocatalytic efficiency and effectively utilize solar energy as well as the use of some of the bad environment for ZnO materials, then we fabricated ZnO-base binary, ternary composite photocatalyst and some InGaN nano materials.Finally, the morphology, crystal structure, surface physical chemistry properties and photocatalytic behavior were characterized, the causes of enhance photocatalytic efficiency were discussed. Some new and interesting results are as following:1. The silver nanoparticles, nanocubes and nanowires were synthesized via microwave condensing reflux method. The different morphologies of silver nano-products were obtained through changing the concentration of Na2S, heating power, reaction time, and surfactant concentration. The results show that the silver nanoproducts have gone through a spherical-cube-linear evolution in the morphology with gradually increasing Na2S concentration from0to1to1.5mM. In addition, the effect of S2" on the morphology and the formation mechanism of silver nanoproducts are further discussed in this study.2. Mono-dispersed ZnO microspheres were synthesized through ultrasonic irradiation using zinc acetate, and triethanolamine. The results indicate that the the products was changed from Zn5(OH)8Ac2·2H2O to ZnO nanoparticles, simultaneously, ZnO nanoparticles assemble into spherical structure under ultrasonic irradiation with the increase of reactin time. UV-vis absorption measurement of as-prepared products at different stages shows that the absorption peaks became sharper and blue-shifted from422to364nm with the change of composition and morphology. Photoluminescence (PL) measurement show that the intensity of the UV emission increased with the increase of reaction time. Photocatalytic tests show that photocatalytic activity will decrease with increasing for size of ZnO particles, which may be related to the size and crystallinity of ZnO particles.3. Novel worm-like Ag/ZnO core-shell heterostructural composites were fabricated using a two-step chemical method. As-prepared silver nanowires were soaked in a solution of zinc acetate and triethanolamine to form worm-like Ag/ZnO core-shell composites under ultrasonic irradiation. The results show that the core-shell composites are composed of single crystal Ag nanowires served as the core, on which dense ZnO particles grow as the shell. The PL intensity of Ag/ZnO heterostructural composites varies and appears the minimum intensity for the sample prepared with Ag of2.8at.%. Moreover, photocatalytic tests show that the Ag/ZnO composites exhibit higher photocatalytic activity compared to pure ZnO particles.4. One-dimensional In2O3/ZnO/Ag heteroarchitectures with high visible-light photocatalytic activity have been successfully obtained by a simple combination of solvothermal process and annealing. The results revealed that the Ag nanowires were encapsulated by In2O3and ZnO nanostructures. By compared with Ag, ZnO/Ag, In2O3/Ag and In2O3/ZnO, the obtained In2O3/ZnO/Ag heteroarchitectures showed strongest the visible-light photocatalytic activity to degrade rhodamine B (RB). With the increase of Ag nanowires, the PL intensity of In2O3/ZnO/Ag heteroarchitectures first decrease and then increase, however, for In2O3/ZnO/Ag heteroarchitectures with higher Ag content (3.8wt%), an even better performance in MB photodegradation was attained.5. Different morphologies of InxGa1-xN nanomaterials were prepared upon Si substrates by APCVD. The results shown that all samples were wurtzite structure, however, the morphology changed from flower to pagoda with the effect of Au catalyst; with the inceeaseing of In content, the intensity of PL for InxGa1-xN nano-crystals increases and blue light zone appears. The pagoda InxGa1-xN show best photocatalytic efficency to degrade acid orange, and has highest efficiency for pH at3.更多还原