硫化钼及其复合材料的光催化产氢研究

发布时间：2018-04-29 02:23

本文选题：硫化钼 + 非晶相　；参考：《郑州大学》2017年硕士论文

【摘要】：近年来,太阳能光催化分解水制氢成为研究的热点之一。硫化钼类材料由于优异的析氢活性、价格低廉、无毒等优点被广泛认为是最具潜力的能取代贵金属的催化剂。然而,硫化钼类材料的光生载流子易于复合,迁移率低,导电性差等缺点限制了其光催化活性。针对以上问题,本文从增大暴露的活性位点的数目、扩展光谱响应范围、促进载流子分离等方面展开研究,具体工作内容如下:(1)通过简单的一步反应法在低温环境下利用盐酸羟胺还原(NH4)2MoS_4合成非晶相MoS_3,并利用X光电子能谱(XPS)、X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等手段对其进行表征;进而以藻红B钠盐(Erythrosin B,简写为EB)为光敏剂,三乙醇胺(Triethanolamine,简写为TEOA)为牺牲剂,测得非晶相MoS_3在最优条件下(10 vol%TEOA,5.0 mM EB,0.1 g MoS_3,pH 9.0)的最大产氢速率高达1190.0μmol·h-1。另外还深入探究了影响体系稳定性的原因,结果表明:在光照过程中,非晶相MoS_3先转变为非晶相MoS_2,然后非晶相MoS_2再转变为晶相MoS_2;并证实了产氢的活性成分是生成的非晶相MoS_2;产氢活性下降的主要原因是光敏剂EB的快速降解和催化剂MoS_3表面活性位点被占据。(2)利用非晶相MoS_3为前驱体合成T-MoS_2+x(T为煅烧温度),并对其作了全面的表征;进而以EB为光敏剂,TEOA为牺牲剂构建了基于MoS_2+x的光催化产氢体系。结果表明:随着煅烧温度的改变,催化剂的组成、形貌、结晶性、比表面积等均发生了改变;煅烧温度对催化剂的产氢性能具有显著影响;在相同测试条件下,300-MoS_2+x表现出极高的产氢活性;在10 vol%TEOA,7.5 mM EB,pH 9.0的最优条件下,300-MoS_2+x的最大产氢速率为1923.5μmol/h,达到煅烧前非晶相MoS_3活性的近1.6倍;循环产氢测试表明催化剂活性的下降同样归因于光敏剂EB的快速降解和催化剂表面活性位点被占据。(3)通过三步水热法成功制备了MoS_2-NiS/CdS三元复合光催化剂,并对其进行一系列表征;利用CdS为固体光敏剂,MoS_2和NiS为双助催化剂实现了可见光下的光催化产氢,详细研究了MoS_2-NiS/CdS在乳酸溶液中的产氢性能和稳定性。实验结果表明:MoS_2-NiS/CdS在最佳条件下(MoS_2的含量为7 wt%,NiS负载量为2 wt%,pH 3.0,乳酸体积为40%)的最大产氢速率可达2525.2μmol·h-1,达到纯CdS的11.3倍;随着循环次数的增加,产氢效率没有出现显著下降,说明所制备的MoS_2-NiS/CdS复合光催化剂具有良好的稳定性。
[Abstract]:In recent years, photocatalytic decomposition of water for hydrogen production by solar energy has become one of the hotspots. Molybdenum sulphide is widely regarded as the most potential catalyst to replace precious metals because of its excellent hydrogen evolution activity, low price and non-toxicity. However, the photocatalytic activity of molybdenum sulfide materials is limited by the disadvantages of easy recombination of photogenerated carriers, low mobility and poor electrical conductivity. In order to solve the above problems, this paper studies on increasing the number of active sites exposed, expanding the spectral response range, promoting carrier separation, etc. The specific work is as follows: (1) Synthesis of amorphous MoS3 by a simple one-step reaction method using hydroxylamine hydrochloride to reduce NH _ 4N _ 2MoS _ 4 at low temperature, and X-ray photoelectron spectroscopy (XPS) X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Tem) was used to characterize it. The maximum hydrogen production rate of amorphous MoS_3 was determined to be as high as 1190.0 渭 mol h-1 under the optimum conditions by using Erythrosin B (EB3) as Guang Min agent and triethanolamine as sacrificial agent. Under the optimum conditions, the maximum hydrogen production rate was 1190.0 渭 mol h-1.The maximum hydrogen production rate was as high as 1190.0 渭 mol h-1. In addition, the reasons that affect the stability of the system are also deeply explored. The results show that: in the process of illumination, The amorphous phase MoS_3 was transformed into amorphous phase MoS _ 2, and then amorphous phase MoS_2 was transformed to crystalline phase MoS _ 2. It was confirmed that the active component of hydrogen production was formed amorphous phase MoS _ 2; the main reason for the decrease of hydrogen-producing activity was the rapid degradation of Guang Min agent EB and the catalyst MoS_3. The surface active site was occupied. (2) the amorphous phase MoS_3 was used as the precursor to synthesize T-MoS_2 XT as calcining temperature, and it was characterized comprehensively. Furthermore, the photocatalytic hydrogen production system based on MoS_2 x was constructed with EB as Guang Min agent and TEOA as sacrificial agent. The results showed that the composition, morphology, crystallinity and specific surface area of the catalyst changed with the change of calcination temperature, and the calcination temperature had a significant effect on the hydrogen production performance of the catalyst. The maximum hydrogen production rate of 300-MoS2x is 1923.5 渭 mol / h under the optimum conditions of 10 vola 7.5 mm EBN pH 9.0, which is about 1.6 times of the MoS_3 activity of the amorphous phase before calcination, and the maximum hydrogen production rate of 300-MoS2x is about 1923.5 渭 mol / h under the same test conditions, and the maximum hydrogen production rate of 300-MoS2x is 1923.5 渭 mol / h under the optimum conditions of 10 volta 7.5 mm EBN pH 9.0. Cyclic hydrogen production test showed that the decrease of catalyst activity was also attributed to the rapid degradation of Guang Min agent EB and the occupation of catalyst surface activity sites. The MoS_2-NiS/CdS ternary photocatalyst was successfully prepared by three-step hydrothermal method and characterized by a series of characteristics. Photocatalytic hydrogen production under visible light was realized by using CdS as solid Guang Min agent MoS _ 2 and NiS as double catalyst. The hydrogen production performance and stability of MoS_2-NiS/CdS in lactic acid solution were studied in detail. The results showed that under the optimum conditions, the maximum hydrogen production rate of mol / CDs reached 2525.2 渭 mol h-1, 11.3 times higher than that of pure CdS, with the maximum hydrogen production rate of 2525.2 渭 mol h-1, which was 11.3 times higher than that of pure CdS, when the load of NiS was 7 wtand the load of NiS was 3.0, and the efficiency of hydrogen production did not decrease significantly with the increase of cycle times. The results show that the prepared MoS_2-NiS/CdS composite photocatalyst has good stability.
【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

【相似文献】