铁、锰三元硫化物的制备及电化学性能研究

发布时间：2018-03-15 01:25

本文选题：三元金属硫化物　切入点：超级电容器　出处：《大连理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：超级电容器、金属-空气电池、电解水制氢等新型电化学储能技术亟需能够提供更大比容量、更高析氢催化活性和更优氧还原／析氧反应双效催化活性的廉价电极材料。Fe基、Mn基功能化材料长期以来受到众多研究者们的关注。而现有研究方法大多致力于调控材料的形貌和结构,对催化剂组成的考察鲜有报道。因此,本文采用纳米二氧化硅为模板制备了不同元素组成的6类含Fe、Mn三元硫化物,并研究了它们的电容性能和电化学催化性能。在热碱溶液中利用不同物系反应速率差异产生的竞争效果,在同一反应体系中先后实现了二氧化硅模板剂对目标材料的支撑和模板剂的去除,氢氧根离子对金属离子的沉淀及后续硫离子对氢氧根的置换,制备方法简便,易分离。本文通过此牺牲模板-竞争硫化法得到形貌均一的硫化钴纳米片。其中,在金属离子浓度为6mmol·ml/1,硫单质用量为30mg·mL-1的反应条件下,加入模板剂后产物的电化学活性表面积相比于未使用模板剂增加了60%,进一步调节模板剂加入量和金属离子总浓度,得到较优的反应条件为金属离子总浓度0.3mmol·mL-1,硫单质用量为10mg·mL-1。在较优的制备条件下得到纳米片层结构的(Cu2Fe)Sx并考察其电容性能,在1mol·L-1 Na2SO3电解液中1A·g-1的电流密度下比容量达437F·g-1,该容量性能在硫化铜的容量报道值中处于较高水平。同时材料在1000W·kg-1的功率密度下显示出具有28Wh·kg-1的较大能量密度。含Fe三元硫化物中Ni-Fe-S、Cu-Fe-S用于析氢反应具有较好电化学催化性能,其中(Ni2Fe)Sx在高过电势区具有最小的Tafel斜率175mV·dec-1,进一步考察不同温度下(Ni2Fe)Sx的析氢催化性能,根据阿伦尼乌斯方程计算得到该材料具有析氢反应活化能12kJ·mol-1。使用断电流法和循环伏安法考察析氢机理,得出该材料表面的析氢反应过程为电化学脱附控制。含Mn三元硫化物Cu-Mn-S、Co-Mn-S、Ni-Mn-S均具有一定的氧还原催化活性,其中(Co2Mn)Sx显示出较优的氧还原/析氧反应双效催化活性和优越的抗一氧化碳、甲醇毒害能力。该材料具有0.59V的氧还原/析氧总体起始电势差,小于商业化20%Pt/C的0.68V。在500mV的析氧过电势下,样品(Co2Mn)Sx的析氧极化电流为Pt/C的6.3倍。
[Abstract]:New electrochemical energy storage technologies, such as supercapacitors, metal-air batteries and electrolytic water for hydrogen production, urgently need to be able to provide greater specific capacity. Low cost electrode materials with higher catalytic activity for hydrogen evolution and double catalytic activity for better oxygen reduction / oxygen evolution reaction. Fe-based mn based functionalized materials have long been concerned by many researchers. However, most of the existing research methods are devoted to regulating. The morphology and structure of the controlled materials, There are few reports on the composition of the catalyst. Therefore, six kinds of Feumn-containing ternary sulfides with different elements have been prepared by using nano-silica as template. Their capacitive properties and electrochemical catalytic properties were also studied. The competitive effects of different reaction rates in hot alkali solution were studied. In the same reaction system, the support of silica template to the target material and the removal of template agent, the precipitation of hydroxide ion to metal ion and the replacement of hydrogen and oxygen radical by subsequent sulfur ion have been realized successively, and the preparation method is simple and convenient. It is easy to separate. In this paper, a uniform cobalt sulfide nanocrystalline was obtained by sacrificial template-competitive vulcanization, in which the concentration of metal ions was 6mmol 路ml / 1, and the amount of sulfur was 30mg 路mL-1. The electrochemical active surface area of the product was increased by 60% compared with that of the unused template, and the addition of template agent and the total concentration of metal ions were further regulated. The optimum reaction conditions were obtained as follows: the total concentration of metal ions was 0.3 mmol 路mL -1, and the amount of sulfur was 10 mg 路mL -1. Under the optimum preparation conditions, the Cu _ 2Fe _ 2O _ x nanolamellae was obtained and its capacitive properties were investigated. The specific capacity of 1A 路g-1 in 1mol 路L ~ (-1) Na2SO3 electrolyte was 437F 路g ~ (-1), which was higher than the reported capacity of copper sulphide. At the power density of 1000W 路kg-1, the material showed a high energy density of 28Wh 路kg-1. Ni-Fe-Sn-Cu-Fe-S in ternary sulfides has good electrochemical catalytic performance for hydrogen evolution. Among them, Ni2FeSx has the smallest Tafel slope of 175mV 路dec-1 in the high over-potential region. The catalytic performance of Ni _ 2FeN _ (Sx) for hydrogen evolution at different temperatures is further investigated. According to Arrhenius equation, the activation energy of hydrogen evolution reaction was calculated by 12 kJ 路mol -1. The mechanism of hydrogen evolution was investigated by means of cut-current method and cyclic voltammetry. It is concluded that the process of hydrogen evolution on the surface of this material is controlled by electrochemical desorption. Co2MnSx showed excellent catalytic activity for oxygen reduction / oxygen evolution and excellent ability to resist carbon monoxide and methanol toxicity. The material has a 0.59 V initial potential difference in oxygen reduction / oxygen evolution. It is less than 0.68 V of commercial PT / C. At 500mV oxygen evolution overpotential, the polarization current of oxygen evolution of sample Co _ 2MnN _ x is 6.3 times that of Pt/C.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ125.12;O646.54

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