过渡金属钨（钼）酸盐的液相合成及其催化性能研究

发布时间：2018-07-14 07:54

【摘要】：钨(钼)酸盐具有良好的化学活性和相似的晶体结构,近年在催化、传感、电化学储能,光学材料等领域得到了广泛重视。目前,钨钼酸盐的合成需要苛刻的条件,常常需要高温合成或固态溶胶凝胶法获得。发展钨钼酸盐合成的新方法,对于深入系统地研究此类纳米材料的结构组成与性能的关系具有重要意义。本论文着眼于发展钨(钼)酸盐材料的液相合成技术,利用简单的一步溶剂(水)热法合成了不同纳米结构的钨钼酸盐,并探究了结构组成与其催化性能的关系。1、通过一步溶剂热法合成了三种不同形貌CoWO4,即纳米片、纳米棒和纳米长方体,借助各种测试手段对CoWO4的结构、组成和形貌进行了详细表征,研究了三种不同形貌CoWO4纳米结构在碱性介质中电催化析氧反应的性能。与另两种CoWO4纳米结构相比,CoWO4纳米片显示出相对优异的电催化性能,具有较小的超电势,较大的催化电流和良好的稳定性。当其电流密度达到10 mA·cm-2时,过电势为436 mV。通过反应前后的X射线衍射(XRD),X射线光电子能谱(XPS)和拉曼光谱分析,我们得出了CoWO4纳米结构电催化析氧反应的可能机理,认为CoWO4纳米片经历了原位电化学所致的结构组成转变,这与其弱结晶度密切相关。2、通过水热法合成了具有相同形貌的MMoO4·nH2O(M=Co,Ni)纳米棒,并对其结构、组成和形貌进行了详细表征,研究了它们在0.1 M KOH溶液中电催化析氧反应的性能。与NiMoO4·nH2O相比,CoMoO4·nH2O具有更低的起峰电位,超电势和更好的稳定性。通过反应前后的XRD和XPS分析,并结合一系列电化学测试结果,我们认为CoMoO4·nH2O的高活性的原因在于较NiMoO4·nH2O具有更为丰富的金属活性位点。3、通过一步溶剂热法合成了分级结构的FeWO4,发现其具有高效的类酶催化活性(即模拟过氧化物酶活性)。在H2O2存在下,它能够催化氧化3,3′5,5′-四甲基联苯胺二盐(TMB)和邻苯二胺(OPD)产生特定的显色反应。在此基础上,我们建立了H2O2和葡萄糖的比色检测法。这种方法操作简单、成本低、灵敏度高,具有较宽的线性范围和较低的检出限。
[Abstract]:Tungsten (molybdenum) salts have good chemical activity and similar crystal structure. In recent years, tungsten (molybdenum) salts have received extensive attention in the fields of catalysis, sensing, electrochemical energy storage, optical materials and so on. At present, the synthesis of tungsten-molybdate requires harsh conditions, and is often obtained by high temperature synthesis or solid sol-gel method. The development of a new method for the synthesis of tungsten-molybdate is of great significance for the in-depth and systematic study of the relationship between the structure composition and properties of such nanomaterials. In this paper, we focus on the development of liquid phase synthesis technology of tungsten (molybdenum) salt materials, using a simple one-step solvent (hydrothermal) method to synthesize different nanostructures of tungsten-molybdate. The relationship between structure composition and catalytic performance was investigated. Three different morphologies of CoWO4 were synthesized by one step solvothermal method, that is, nanomaterials, nanorods and nano-cuboids. The structure of CoWO4 was investigated by various testing methods. The composition and morphology of CoWO4 nanostructures were characterized in detail. The properties of electrocatalytic oxygen evolution reaction of three kinds of CoWO4 nanostructures in alkaline medium were studied. Compared with the other two kinds of CoWO _ 4 nanostructures, CoWO _ 4 nanocrystals show relatively excellent electrocatalytic performance, small superpotential, large catalytic current and good stability. When the current density is up to 10 Ma cm-2, the overpotential is 436mV. Through X-ray diffraction (XRD) X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, we obtained the possible mechanism of electrocatalytic oxygen evolution reaction of CoWO4 nanostructure. This is closely related to its weak crystallinity. MMoO4nH2O nanorods with the same morphology were synthesized by hydrothermal method. The structure, composition and morphology of the nanorods were characterized in detail. The properties of their electrocatalytic oxygen evolution reaction in 0.1 M Koh solution were studied. Compared with NiMoO _ 4nH _ 2O, CoMoO _ 4nH _ 2O has lower peak initiation potential, higher potential and better stability. XRD and XPS analysis before and after the reaction, and a series of electrochemical results, We think that the reason for the high activity of CoMoO _ 4nH _ 2O is that it has more metal active sites than NiMoO _ 4nH _ 2O. FeWO4 was synthesized by one-step solvothermal method, and it is found that it has high activity of enzymatic catalysis (that is, mimic peroxidase activity). In the presence of H _ 2O _ 2, it can catalyze the oxidation of TMB and OPD to produce a specific color reaction. On this basis, we established a colorimetric method for the detection of H _ 2O _ 2 and glucose. This method has the advantages of simple operation, low cost, high sensitivity, wide linear range and low detection limit.
【学位授予单位】：西华师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O643.36

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