【作者】 向群；

【导师】 施利毅；

【作者基本信息】 上海大学 ， 材料学， 2008， 博士

【摘要】 纳米材料制备及应用是当今世界各国重点发展的研究领域之一。一维纳米材料由于其新颖的物理、化学和生物特性以及在纳米器件中的潜在用途成为当今纳米技术的研究热点。本文对一维氧化锌基复合纳米材料的制备及其气体敏感性能和光催化活性进行了系统研究。对传统水热/溶剂热法进行了改进,设计了一种简单的前驱物超声辅助—水热/溶剂热法,在120℃低温合成了结构均匀、分散性好、产率高的氧化锌纳米棒,发现前驱物溶液先经过超声处理,产生部分氧化锌晶核作为晶种再进行水热/溶剂热反应,能提高纳米棒的产率和均匀性。系统研究了辅助剂、反应温度和时间等影响因素对氧化锌纳米结构和形貌的影响,结果表明阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）和有机高分子表面活性剂PEG400是合成一维氧化锌的最佳辅助剂。创新性地将固体原料乙酸锌和氢氧化钠直接置于含PEG400辅剂的乙醇溶剂中,在120℃的低温中一步合成了直径约20nm的氧化锌纳米线和纳米棒,研究发现氢氧化钠的比例是控制纳米氧化锌长度的关键,从而实现了氧化锌一维纳米材料的可控合成。提出氧化锌纳米棒、纳米线的生长机理为溶解—醇解—成核—生长机制。采用静态配气法测试了不同结构纳米氧化锌的气敏性能。与零维纳米粒子相比,一维氧化锌纳米材料具有较高的气体灵敏度和较好的气敏稳定性;通过气敏元件表面分析和比表面测试分析,推断出氧化锌一维纳米结构灵敏度高于零维结构的主要原因是,气敏材料经高温烧结制成气敏元件后,一维氧化锌能够保持自身形貌并形成大量空穴,具有较高的有效表面积。独创了氧化物气敏材料的贵金属量子点修饰法,有效地提高了氧化物气敏材料的灵敏度和选择性。采用液相法合成了贵金属量子点（Pd,Pt）,研究发现贵金属量子点修饰法较之传统的浸渍煅烧掺杂法更为有效、方便。采用钯量子点修饰氧化锌纳米线后可以得到超高灵敏度和高选择性的硫化氢气体传感器,可以检测ppb级的硫化氢气体。铂量子点修饰氧化锌纳米线后的气敏性能也有明显改善,对酒精、甲醛气体的检测下限也有所降低。采用了一种简单的光化学沉积法制得了Ag负载ZnO纳米棒的新型气敏材料,气敏性能研究结果表明,这种新型的气敏材料具有优良的气敏性能,可以检测ppm级的酒精。根据氧化锌和氧化钨均能形成一维纳米材料且都具有良好地光催化性能,这两种氧化物的复合产物钨酸锌也应能形成一维纳米材料并具备良好的光催化性能这样的思路,采用了一种简单的、不加任何辅助剂的沉淀—水热法合成了直径约20nm,长度约200nm且结构均匀、分散性好、产率高的钨酸锌纳米棒。系统研究了反应温度、时间对一维纳米结构形成和结晶度的影响,提出了钨酸锌纳米棒的生长机理为成核—成棒—晶化过程。并研究了不同条件下制备的钨酸锌纳米棒的光致发光性能以及对有机染料罗丹明B的光催化降解效率。发现水热温度为200℃,反应时间为16小时得到的产品直径小、形貌均一、结晶度高、荧光发射强度高且对罗丹明B的光催化降解效率高,几乎可以和高效光催化剂TiO₂（Degussa P-25）媲美。更多还原

【Abstract】 Today the synthesis and the application of nanomaterials has become one of the key research areas for countries all over the world. One dimensional nanomaterials are now the hop spot of research of nanotechnologies because of their fresh new physical, chemical and biological properties and their potential usage in the nano-instruments. So we conducted a systematic reasearch on the synthesis of one dimensional ZnO based nanomaterials and their gas sensitivity and photocatalytic properties.The traditional hydrothermal solution method was modified and a simple precursor ultrasonic-assisted-hydrothermal solution method was designed. At the temperature of 120℃, the ZnO nanorods were synthesized with this method, the nanorods with high output were uniform in structure and well dispersed. The results show that the output and uniformity of the nanorods could be improved if the precursor solution was ultrasound treated and some ZnO crystal nucleus thus produced as crystal seeds had been reacted in hydrothermal-solution reaction. We systematically studied the influence factors like assistants, reaction temperatures and reaction time that affected the ZnO nano morphologies and structures. The results demonstrate that the cationic surfactant CTAB and the organic macromolecule surfactant PEG400 are the best assistants for control synthesis of one-dimensional ZnO.The solid ZnAc₂·2H₂O and NaOH were creatively used as raw materials, and were put into the alcoholic solution that contained PEG400 as assistants and at the low temperature of 120℃, ZnO nano wires and nanorods could be synthesized at one step, their diameters were around 20 nm. The percentage of NaOH plays a key role in controlling the length of ZnO nanomaterials. Thus we suggest that the ZnO nanorods and nanowires’ growth mechanism is dissolution-alcoholysis-nucleation mechanism.The gas sensing properties of ZnO nanomaterials with different structures were measured by mixing detected gas and air in static state. In comparison with ZnO nanoparticles, one- dimensional ZnO nanomaterials have higher gas sensitivity and better gas sensing stability. One-dimensional ZnO nanostucture was higher in gas sensitivity than zero dimensional structure. Through analysis with SEM photographs and data of specific surface area, we concluded the main reason to be that after the gas sensor had been sintered through high temperature, one dimensional ZnO may retain its morphology and form large amount of gas channels that provided relatively high effective surface area.The creative modification with Pd and Pt quantum dots （QDs） method on oxide gas sensing materials had effectively increased the sensitivity and selectivity of the sensors. Pd and Pt QDS were synthesized with solution-grown method and the study found that the modification with Pd and Pt QDS method was more effective and convenient than the traditional doped method. We used Pd QDs to modify ZnO nanowires, thus we got the highly sensitive and highly selective H₂S gas sensor. The sensor can detect H₂S gases of ppb grade. After being modified by Pt QDs, the gas sensitivity of the ZnO nanowires had improved considerably, the minimum amount of alcohol and HCHO it could detect had lowered.A simple photochemical precipitation method was used to synthesize a new gas sensitive material of Ag-doped ZnO nanorods. The results show that this new type of material had outstanding gas sensing capability and can detect alcohol at ppm grade.Since ZnO and WO3 can both be synthesized into one-dimensional nanomaterials and have good photocatalytic properties, their compound ZnWO₄ might be synthesized into one-dimensional nanomaterials and could have good photocatalytic properties. A simple precipitation-hydrothermal method was used without any assistants to synthesize the ZnWO₄ nanorods that were uniform in structures, well dispersed, of high output and had the diameter of 20 nm and length of around 200 nm. We systematically studied the influence of reaction temperature and time on the formation and degree of crystallization of one-dimensional nanostructure. And we propose the growth mechanisms of the ZnWO₄ nanorods to be nucleation-nanorods forming-crystallization. We studied the photoluminescence performance of the ZnWO₄ nanorods synthesized under different conditions and their photocatalytic degradation efficiency of the organic dye RhB. We found that at the temperature of 200℃with reaction time of 16 hours, the products we got was of small diameters, uniform in morphologies, high in fluorescence emissive power, of high crystallization and its photocatalytic degradation efficiency of RhB was so high that it was almost comparable to the highly efficient catalyst TiO₂ （Degussa P-25）.更多还原