纳米棒阵列电极的控制合成及其催化析氢性能研究

发布时间：2018-04-09 03:00

本文选题：析氢催化剂　切入点：纳米棒阵列　出处：《重庆大学》2015年硕士论文

【摘要】：氢能源由于资源丰富、安全清洁、性能优越,在未来极有可能替代化石燃料而受到人们的高度重视。氢气可通过多种途径制备,其中电解水制氢技术利用太阳能等可再生能源,其工艺简单,无污染,是实现氢时代的最佳制氢方法。更重要的是,水和氢气间的转变可以实现电能和化学能之间的转化。传统的高性能析氢电极材料主要为铂族贵金属,但其储量有限且价格昂贵,无法实现大规模生产。这就迫切需要研发价廉且丰富的材料来降低制氢技术的成本,以致将来实现氢能经济。此外,现有析氢催化剂的制备方法大多存在工艺过程复杂、形貌难以控制、龟裂现象难以避免等问题。因此,寻找简单清洁的新型制备方法,生产具有低成本、高催化活性和稳定性的阴极析氢材料具有重要的研究意义和使用价值。①采用简单可控的乙二醇调控水热法以及后续热处理,在泡沫Ni基底上原位生长Ru O2-Ni O纳米棒,制备出具有高催化活性和稳定性的析氢电极。乙二醇与过渡金属间较强的配位效应使得其可以与Ru Cl3或Ni Cl2络合形成金属醇化物,并以此作为成核位点逐渐组装形成规整的纳米棒阵列。SEM图显示Ru O2-Ni O纳米棒阵列垂直生长在Ni foam基底上,其长度为1-2μm。电化学测试表明,Ru O2-Ni O电极显示出优越的析氢催化活性及稳定性。Ru O2-Ni O/Ni foam电极的起始电位比Ni foam电极正移175 m V,其活性比表面积是Ni foam电极的15倍,是Ni O/Ni foam电极的23倍;Ru O2-Ni O/Ni foam电极的交换电流密度(j0)为2.24×10-3 A cm-2,比Ni foam和Ni O/Ni foam电极高两个数量级;在η=100 m V时,Ru O2-Ni O/Ni foam电极的反应电阻(Rct)为0.50Ω,显著小于Ni foam(35.93Ω)和Ni O/Ni foam(173.60Ω),说明Ru O2-Ni O/Ni foam电极具有更优的析氢催化活性。这种优越的电化学性能来源于电极材料独特的纳米结构。电极表面的氧化镍/氢氧化镍物种能有效促进水分子的离解以及吸附氢原子的形成,随后形成的吸附氢原子在附近的钌物种上脱附并快速形成氢气分子。这种直接在导电基底上水热合成纳米阵列材料的方法,为Ni-基析氢电极材料的制备及实际应用提供了有效可行的新方法。②采用高效可控的磁控溅射技术,在泡沫Ni基底上制备Ni-Mo合金纳米棒阵列析氢催化剂。Ni-Mo合金催化剂表现出非晶态结构,有利于吸附氢原子(Had)的电化学脱附;SEM表征显示,电极表面由高度规整的纳米颗粒组成,直径约为50 nm,SEM横截面图显示电极表面是垂直于基底的纳米棒阵列结构,其长度约为1μm。纳米棒阵列结构有利于气泡从电极表面快速逃逸,减弱电解质的扩散阻力;Ni-Mo/Ni foam电极的活性比表面积是Ni/Ni foam电极的5倍,表明Mo元素可以显著提高Ni电极的粗糙度,由此提高其催化活性;在η=60 m V时,Ni-Mo/Ni foam电极的反应电阻为1.59Ω,比Ni foam(65.86Ω)、Ni/Ni foam(13.03Ω)和Mo/Ni foam(22.89Ω)电极均小很多,说明Ni-Mo/Ni foam电极具有更优的析氢催化活性。由此可知,Ni-Mo合金电极表现出优越的催化活性,其原因有二:一是独特的纳米棒阵列结构为反应提供了丰富的活性位点;二是Ni和Mo元素间的协同效应增加了电极本身的催化活性。更普遍的是,这种电极结构的纳米精细设计为催化剂的发展提供了一种宝贵的方法,同时这种方法也适用于其他析气电极的设计与制备。
[Abstract]:Hydrogen energy is rich in resources, safe and clean, superior performance, in the future is likely to replace fossil fuels and attention. Hydrogen can be prepared through a variety of ways, including water electrolysis technology using renewable energy such as solar energy, has the advantages of simple process, no pollution, is to achieve the best times. More hydrogen hydrogen production method it is important that the shift of water and hydrogen can be achieved between electrical energy and chemical energy. The conversion between high performance hydrogen electrode material is the traditional main platinum group metals, but its reserves are limited and expensive, unable to achieve large-scale production. There is an urgent need to develop cheap and abundant materials to reduce the hydrogen production technology. The cost that the future hydrogen economy. In addition, the existing hydrogen catalyst preparation process are complex, difficult to control the morphology, cracking phenomenon is difficult to avoid such problems. Because of this, looking for Jane A new preparation method of single clean production, has the advantages of low cost, cathodic hydrogen material with high catalytic activity and stability and use value has important significance. The regulation of ethylene glycol by hydrothermal method is simple and controllable and the subsequent heat treatment, in situ growth of Ru O2-Ni O nanorods in foam Ni substrate prepared by analysis the hydrogen electrode has high catalytic activity and stability. Ethylene glycol and transition metal strong coordination effect makes it possible to form metal alcoholate with Ru Cl3 or Ni Cl2 complex, and as a nuclear site gradually assembled nanorods array form a regular column.SEM figure shows the Ru O2-Ni vertical O nanorod arrays grown on Ni substrate foam on that, its length is 1-2 M. Ru O2-Ni O electrochemical electrode showed initial potential electrocatalytic activity and stability of.Ru O2-Ni O/Ni foam electrode superior than the Ni foam 175 m V positive electrode, The active surface area is 15 times the Ni foam electrode, foam electrode is 23 times Ni O/Ni; Ru O2-Ni O/Ni exchange current density of foam electrode (J0) was 2.24 * 10-3 A cm-2, Ni foam and Ni O/Ni than the foam electrode is two orders of magnitude higher in =100 m; ETA V, reaction resistance Ru O2-Ni O/Ni foam electrode (Rct) is 0.50, significantly less than the Ni foam (35.93) and Ni O/Ni foam (173.60), Ru O2-Ni O/Ni foam electrode has better catalytic activity for hydrogen evolution. The superior electrochemical performance of nanostructured electrode materials derived from the unique NiO / electrode surface. The nickel hydroxide species can effectively promote the dissociation of water molecules and the formation of adsorbed hydrogen atoms, hydrogen atom in the subsequent formation of ruthenium species near the desorption and rapid formation of hydrogen molecules. This method directly in the nano conductive substrate water thermal synthesis array material, Ni- based hydrogen electrode material The material preparation and application provides a new and effective method. The magnetron sputtering technique using the highly controllable, the preparation of amorphous Ni-Mo alloy structure exhibits nanorod arrays of hydrogen catalyst.Ni-Mo catalyst in Ni alloy foam substrate, is conducive to the adsorption of hydrogen atoms (Had) electrochemical desorption; SEM characterization showed that the surface of the electrode is composed of nano particles are highly structured, is about 50 nm in diameter, SEM cross section diagram shows that the electrode surface is nanorod arrays perpendicular to the substrate, the length is about 1 m. nanorod arrays to bubble rapid escape from the electrode surface, weaken the diffusion resistance of electrolyte; Ni-Mo/Ni foam electrode surface active the area is 5 times the Ni/Ni foam electrode, showed that Mo element can significantly improve Ni electrode roughness, thereby improving its catalytic activity in M V; =60 Ni-Mo/Ni, the reaction resistance of foam electrode is 1.59 ohms, Ni foam (65.86), Ni/Ni foam (13.03) and Mo/Ni foam (22.89) electrode was much smaller, indicating that Ni-Mo/Ni foam electrode has better catalytic activity for hydrogen evolution. Therefore, Ni-Mo alloy electrodes showed superior catalytic activity, there are two reasons: one is to provide rich active sites the unique structure of the nanorod arrays for reaction; two is the synergistic effect of Ni and Mo elements increased the catalytic activity of the electrode itself. More generally, the electrode structure of Nano fine design for catalyst development provides a valuable method for design and manufacture, and this method is also applicable to other gas electrode the preparation.

【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O646.54;TQ116.2

【相似文献】