介孔镍钴催化剂的制备及其在微生物电解池阴极反应中的应用

发布时间：2018-03-15 19:38

本文选题：SBA-15　切入点：硬模板　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：在能源枯竭、环境恶化的时代背景下,寻求新型绿色能源迫在眉睫。绿色氢能能够在很大程度上解决能源危机等问题。众多制氢方式中,微生物电解池(MEC)由于自身的诸多优势脱颖而出,赢得科研学者的重视。本论文以MEC阴极镍钴氧化物催化材料为研究重心,以介孔硅为硬模板,进行了一系列实验,探讨了不同浸渍方法,不同镍、钴硝酸盐前驱体比例,不同焙烧温度以及焙烧环境对介孔镍钴氧化物的影响,并对比了所制备样品的电化学及MEC阴极析氢性能,主要实验与结论如下:(1)考查浸渍方法对微-介孔Ni O催化剂以及MEC阴极析氢量的影响。以SBA-15为硬模板,硝酸镍为浸渍前体制得短程有序的介孔Ni O,其中双溶剂法制备的介孔Ni O在疏水性溶剂正己烷作用下,对孔道的填充较为完全,较好的复制了SBA-15的有序介孔结构,所得介孔Ni O比表面积(123m2/g),以及微孔面积(169 m2/g)均远远高于其他几种浸渍方法(介孔80m2/g,微孔107 m2/g)。双溶剂合成法相对于其他方法更有利于金属前体进入SBA-15的微孔孔道,因此双溶剂法电极材料具有丰富的微孔,进而导致活性位点增多,与此同时,该电极材料丰富的介孔孔道还便于电解液离子的传输,促进了材料倍率性能的改善。相对比其他几种方法,由双溶剂法制得的富含微孔的介孔结构Ni O在MEC析氢实验中的氢气选择性最好。(2)采用硬模板法,利用双溶剂法浸渍,以不同摩尔比的镍钴硝酸盐为前体,制备得到微-介孔镍钴氧化物。通过XRD和N_2吸附等分析手段可知:随着镍掺杂比例的增加,晶胞参数a0值逐渐增大,Ni O的峰出现并逐渐增强,Co3O4的峰减弱消失,当镍钴摩尔比为1:2时,镍离子进入钴尖晶石的晶格,生成了镍钴尖晶石结构。介孔Ni Co_2O_4的介孔比表面积为100m2/g,微孔比表面积78 m2/g。高的微介孔比表面积和有序介孔孔道结构导致Ni Co_2O_4电极较优的电化学性能。究其原因,可能是由于尖晶石的特殊结构,导致Ni Co_2O_4析氢催化效果优于其他比例样品,氢气含量达到68.96%,析氢总量达到8.5 ml。(3)采用不同焙烧温度制备微-介孔镍钴氧化物。低温焙烧(300℃)时,可得到较为纯净的Ni Co_2O_4单相,而温度升高至400℃以上时,Ni Co_2O_4尖晶石开始分解形成Ni O,形成有缺陷的尖晶石结构。当温度达到800℃,出现Co O结构衍射峰。500℃焙烧温度时,介孔表面积(129 m2/g),微孔面积(166 m2/g)最为丰富,此时带有Ni O缺陷的镍钴尖晶石的CV曲线面积明显高于单纯的镍氧化物或者钴氧化物。由于受到比表面积与结晶度的双重影响,在焙烧温度为500℃,镍钴摩尔比为1:2时,得到的微-介孔镍钴氧化物具有最高的比表面积和较好的孔径分布,在自组装的单室MEC装置中得到较好的析氢效果。(4)探究带盖坩埚与开放坩埚在煅烧过程中对材料的晶体生长行为的影响。带盖坩埚中的Ni Co(C)样品的BET比表面积(118 m2/g),微孔面积(58 m2/g),均高于无盖坩埚中样品Ni Co(O),获得了较高有序度的介孔金属氧化物。将最优实验方案:双溶剂浸渍法、镍钴前体摩尔比1:2、500℃带盖坩埚焙烧,推广至硬模板KIT-6,同样得到了有序度较好的镍钴Ni Co_2O_4,样品比表面积的达到101 m2/g。
[Abstract]:In the energy depletion, deterioration of the environment under the background of the times, seeking new green energy imminent. Green hydrogen can solve the problem of energy crisis in a large extent. Many hydrogen production methods, microbial electrolysis cell (MEC) because of its many advantages in science research scholars talent shows itself, to win attention. This thesis MEC cathode nickel cobalt oxide catalyst materials for research, using mesoporous silica as a hard template, conducted a series of experiments on different impregnation methods, different nickel, cobalt nitrate precursor ratio, the influence of different calcination temperature and calcination conditions on Mesoporous Nickel Cobalt oxide, and compared the electrochemical cathodic hydrogen and MEC prepared the main results and conclusions are as follows: (1) to examine the impregnation method of micro - mesoporous Ni O MEC catalyst and the amount of cathodic hydrogen. The effect of using SBA-15 as hard template for impregnating nickel nitrate precursor to short-range order The mesoporous Ni O, the double solvent method for preparing mesoporous Ni O in hydrophobic solvent hexane under the action of pore filling is complete, the mesoporous structure of a good copy of SBA-15, the specific surface area of mesoporous Ni O (123m2/g), and the surface area (169 m2/g) were far much higher than other types of impregnation method (mesoporous 80m2/g, microporous m2/g 107). The double solvent method compared to other methods is more conducive to the pore pore into the metal body before SBA-15, so the double solvent extraction electrode material has rich pores, resulting in increased active sites, and at the same time, the transmission of mesopores rich the electrode material also for electrolyte ions, promoted the rate performance of the material improved. Compared to other methods, the double solvent prepared rich microporous mesoporous structure of Ni O MEC in the best hydrogen selectivity of hydrogen evolution experiment. (2) by hard template method, and Impregnated with double solvent method using nickel cobalt nitrate with different molar ratios were prepared by micro - mesoporous nickel cobalt oxide. By XRD and N_2 adsorption analysis method shows that with increasing Ni doping ratio, the lattice parameter A0 increases, the peak of Ni O and Co3O4 gradually increased. The peak weakened and disappeared, when the Ni / co molar ratio is 1:2, nickel ions into the cobalt spinel lattice generated nickel cobalt spinel structure. The mesoporous Ni Co_2O_4 mediated 100m2/g specific surface area, micropore surface area of 78 m2/g. high dielectric micro pore surface area and ordered mesoporous channel structure leads to the electrochemical properties of Ni Co_2O_4 the electrode is better. The reason may be due to the special structure of Ni Co_2O_4 spinel, leading to hydrogen evolution is better than other proportion of samples, the hydrogen content reached 68.96%, the hydrogen evolution volume reached 8.5 ml. (3) with different calcination temperature for preparing micro - and Mesoporous Nickel Cobalt Oxide. Roasting at low temperature (300 DEG C), can obtain more pure single-phase Ni Co_2O_4, while the temperature rises to 400 degrees above, Ni Co_2O_4 Ni O began to form spinel decomposition, the formation of spinel structure defects. When the temperature reaches 800 DEG C, Co O diffraction peak of.500 DEG C calcination temperature, mesoporous the surface area (129 m2/g), surface area (166 m2/g) is the most abundant, the area of CV curve at Ni O with nickel cobalt spinel defect was obviously higher than that of pure nickel oxide or cobalt oxide. Due to the double influence than the surface area and the crystallinity of the calcination temperature at 500 DEG C, Ni / CO molar ratio is 1:2 when the micro - and mesoporous nickel cobalt oxide has the highest specific surface area and good pore size distribution, obtained good effect in a single hydrogen chamber MEC self-assembly device. (4) explore with crucible cover and open crucible in the calcination process of materials for crystal growth Effect of long behavior. With a cover in the crucible of Ni Co (C) BET of the sample surface area (118 m2/g), surface area (58 m2/g), were higher than those without cover in the crucible samples of Ni Co (O), obtained mesoporous metal oxides have high degree of order. The optimal experimental scheme: double solvent the impregnation method, nickel cobalt precursor 1:2500 molar ratio of C with crucible cover roasting, extended to the hard template KIT-6, are also well ordered nickel cobalt Ni Co_2O_4 sample surface area up to 101 m2/g.

【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;O646.5

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