金属有机框架模板法制备二硫化钼复合材料及光催化分解水产氢研究

发布时间：2018-02-24 04:26

本文关键词： 金属有机框架结构模板多孔材料二硫化钼光催化产氢　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：自1972年Fujishima和Honda等人首次报道Pt-TiO_2电极上的水光解现象以来,半导体作为水分解催化剂的应用受到广泛关注,此类研究中催化剂的合成尤为重要。金属有机框架(MOFs)材料可以作为模板合成形貌可控、孔洞均匀、比表面积大的结构,在催化材料的制备方面逐渐展现出诸多优势。近年来,二硫化钼因具有超高的催化活性和低廉的造价而颇具竞争力,与其他材料的复合迅速成为研究热点。为了解决二硫化钼基材料尺寸太大和活性位点不够的问题,本文选择两个经典的MOFs结构为模板合成得到基于二硫化钼的复合材料,并将其应用于光、电催化分解水产氢的研究,证明MOFs作为模板能够实现二硫化钼基复合催化材料的可控合成,为此类材料的实际成产提供理论依据和研究基础。具体工作内容如下:(1)利用NH_2-MIL-125(Ti)为前驱体,与硫脲、钼酸钠在高温下制备出水热法得到花状的多孔MoS_2@TiO_2三维复合光催化剂,接着全面分析其结晶类型、微观结构、组成元素及价态,并对其光学性质和电学性质进行研究。在与光敏剂荧光素(Fl)和牺牲剂三乙醇胺(TEOA)共同构筑成三组分光催化体系后,考察了该催化体系的光催化产氢性能。此外,文章对影响体系产氢活性的因素进行筛选,证明在荧光素为光敏剂,10 vol%TEOA,丙酮与水1:3,p H=11,14.6 wt%Mo S2的条件下,该催化剂的产氢速率极高,可达10046μmol h~(-1)g~(-1)。同时,文章对产氢体系的稳定性和电子传输过程进行较为深入的探究:循环产氢实验表明,该复合光催化剂具有良好的产氢稳定性,经历三次共33小时的循环后,体系的产氢效率并无明显变化;一系列稳态荧光和荧光寿命测试证明,在经过可见光激发后,光敏剂通过还原猝灭将电子传递给催化剂,进行催化产氢反应。(2)利用金属(Ni,Zn,Cu)掺杂的ZIF-67(Co)前驱体与硫脲、钼酸钠合成并筛选得到孔洞结构丰富的三维Cu_(0.9)Co_(2.1)S_4@MoS_2复合光催化剂,并对其进行一系列表征。该催化剂可以在纯水相中进行稳定催化,避免了使用有机溶剂带来的二次污染。经过对产氢条件的筛选,证明掺杂金属铜(比例为Cu:Co=3:7)且二硫化钼负载量为25.8 wt%的复合光催化剂,在TEOA含量为5.3vol%、p H=13的纯水体系中,催化效果最佳,产氢量可以达到19058μmol h~(-1)g~(-1)。此外本论文中不仅对电子的传输渠道进行证明,也利用光电流响应实验和电化学阻抗实验对文中合成催化剂的成功复合进行说明验证。
[Abstract]:Since the reported water photolysis phenomenon of Pt-TiO_2 on the electrode for the first time since 1972 Fujishima and Honda et al., application of semiconductor as water decomposition catalyst has attracted wide attention, synthesis catalyst in such studies is particularly important. Metal organic frameworks (MOFs) materials can be used as a template forming pore morphology controllable, uniform, large surface area structure in catalysis material preparation has gradually showed many advantages. In recent years, because of its ultra high catalytic activity of molybdenum disulfide and low cost and competitive, and other composite materials rapidly become a research hotspot. In order to solve the problem of too large and active sites of the problem of insufficient MoS2 based material size, this paper synthesized MoS2 Composite template based on the MOFs structure of the two classic, and applied to the study of catalytic decomposition of hydrogen light, electricity, proof of MOFs as a template to The controllable synthesis of MoS2 based composite materials, such as material of actual production and provide a theoretical basis and research basis. The specific works are as follows: (1) using NH_2-MIL-125 (Ti) as precursor, and thiourea, sodium molybdate prepared at high temperature water thermal method to obtain three-dimensional composite photocatalyst porous flower like MoS_2@TiO_2 then, a comprehensive analysis of the crystallization type, microstructure, composition and valence, and Study on its optical and electrical properties. With the photosensitizer fluorescein (Fl) and sacrifice triethanolamine (TEOA) to establish the three components of the photocatalytic system, the catalytic system of photocatalytic hydrogen production performance were investigated. In addition, the factors that affect the system of hydrogen production activity screening, demonstrated in fluorescein as photosensitizer, 10 vol%TEOA acetone and water 1:3, S2 P H=11,14.6 wt%Mo under the condition of high hydrogen production rate of the catalyst can be. Up to 10046 mol h~ (-1) g~ (-1). At the same time, the stability and the electron transfer process of hydrogen production system in a more in-depth inquiry: circulating hydrogen production experiments showed that the composite photocatalyst has good stability of hydrogen production, a total of 33 hours after three cycles, no hydrogen production efficiency system the obvious change; a series of fluorescence and fluorescence lifetime test proved that after the visible light excitation, the photosensitizer electron transfer quenching catalyst reduction, hydrogen production using a catalytic reaction. (2) the use of metal (Ni, Zn, Cu) doped ZIF-67 (Co) precursor and thiourea, sodium molybdate and synthesis screened Cu_ three-dimensional structure rich hole (0.9) Co_ (2.1) S_4@MoS_2 composite photocatalyst, and a series of characterization of the catalyst. The catalytic stability can be carried out in water phase, avoid pollution two bring. After the use of organic solvents on hydrogen production conditions of the screen That election, doping copper (Cu:Co=3:7 ratio) and the load of MoS2 Composite Photocatalyst wt% 25.8, the content of TEOA is 5.3vol%, P, H=13 in water system, the best catalytic effect, hydrogen yield can reach 19058 mol h~ (-1) g~ (-1). In addition, this thesis not only for transmission the electronic channels that use the photocurrent response and electrochemical impedance experiments on the synthesis of the composite catalyst is described successfully verified.

【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ116.2

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