三维Ni-Co羟基氧化物电极材料的原位活化及其性能研究

发布时间：2018-12-12 21:28

【摘要】：生长于柔韧基底上的三维纳米结构阵列电极在柔性电子元件的应用上显示出极大的潜力。本论文设计制备了一系列生长于碳布上的Ni-Co基氢氧化物纳米材料,并对其电容行为进行了研究。同时,考虑到Ni-Co基化合物在电催化领域的优秀表现,我们也对所合成的纳米阵列电极催化析氧反应的行为进行了探讨。首先,研究了制备高性能电极的Ni-Co氢氧化物阵列的原位转化过程。通过常用的水热手段得到在碳布上生长的Ni-Co碱式碳酸盐纳米针状阵列,其在碱液中浸泡后逐渐转变为Ni-Co羟基氧化物纳米线支撑的纳米片阵列。随着浸泡时间的增加,在1 mA·cm-2的电流密度下其容量从281 mF·cm-2显著增加到3900 mF·cm-2。并且库伦效率也可达到了100%。这种纳米线支撑纳米薄片阵列具有通畅的传质通道、大的比表面积为电解液离子的扩散和表面接触提供便利,同时其三维结构稳定性高,保证了电极具有很好的电容性能。此外,由相应电极片组装的不对称电容器在碱液中浸泡24 h后面积比电容也有增加。其次,讨论了不同Ni/Co摩尔比对电极原位转化效果的影响。发现改变Ni和Co组分的相对含量对电化学性能有明显影响。当Ni/Co= 1.5:1时,电极材料的性能最优。在6 mol·L-1 KOH中,2.0 mA·cm-2的电流密度下电容由初始的1987.6 mF·cm-2增大到4543.8 mF·cm-2。从样品浸泡前后的阻抗谱,以及单组分碱式碳酸盐的形貌变化,可以判断Co和Ni组分在形貌及电化学性能中的作用。Ni-Co碱式碳酸盐阵列纳米针阵列的形成是Co化合物的生长习惯所致,而纳米针向纳米薄片的转变是由于Ni氢氧化物的生长趋势所诱导,Co组分对浸泡过程的电容值变化影响较大。Ni组分可改善电极导电能力。最后,碳布可以作为柔性基底,形成高催化活性的OER电极。通过水热法在碳布上生长Ni-Co-Fe碱式碳酸盐纳米针阵列电极,实验结果表明,初始的Ni-Co-Fe/CC碳酸盐电极在10 mA·cm-2的电流密度下的过电势为402 mV,有最小的Tafel斜率为72 mV·dec-1,而在6 mol·L-1 KOH的溶液中浸泡10h后η10最小,为340mV。
[Abstract]:Three-dimensional nanostructured array electrodes grown on flexible substrates show great potential in the application of flexible electronic components. In this paper, a series of Ni-Co based hydroxide nanomaterials grown on carbon cloth have been designed and prepared, and their capacitance behavior has been studied. At the same time, considering the excellent performance of Ni-Co based compounds in the field of electrocatalysis, we also discussed the behavior of the synthesized nanoscale array electrodes for catalytic oxygen evolution. Firstly, the in situ conversion of Ni-Co hydroxide arrays with high performance electrodes was studied. The Ni-Co basic carbonate nanowire arrays grown on carbon cloth were prepared by hydrothermal method. After soaking in alkali solution, they were gradually transformed into Ni-Co hydroxyl oxide nanowires supported by nanowires. With the increase of soaking time, its capacity increased significantly from 281 mF cm-2 to 3900 mF cm-2. at 1 mA cm-2 current density. And Coulomb efficiency can also reach 100. The nanowire supported nanoscale array has a smooth mass transfer channel and a large specific surface area to facilitate the diffusion and surface contact of electrolyte ions. At the same time, the three-dimensional structure stability of the nanowire array is high, which ensures the electrode has good capacitance performance. In addition, the area specific capacitance of the asymmetric capacitor assembled by the corresponding electrode sheet increased after immersion in the alkaline solution for 24 hours. Secondly, the effect of different molar ratio of Ni/Co on in situ conversion of the electrode was discussed. It is found that changing the relative content of Ni and Co has a significant effect on the electrochemical performance. When Ni/Co= is 1.5: 1, the electrode material has the best performance. In 6 mol L-1 KOH, the capacitance of 2.0 mA cm-2 increased from 1987.6 mF cm-2 to 4543.8 mF cm-2. at current density. From the impedance spectrum of the sample before and after soaking, as well as the morphology change of the one-component basic carbonate, The effects of Co and Ni components on morphology and electrochemical properties can be judged. The formation of Ni-Co basic carbonate array nano-needle arrays is due to the growth habits of Co compounds. However, the transition from nano-needle to nanoscale is induced by the growth trend of Ni hydroxide, and the Co component has a great effect on the change of capacitance during soaking. The Ni component can improve the conductivity of the electrode. Finally, carbon cloth can be used as a flexible substrate to form OER electrode with high catalytic activity. Ni-Co-Fe basic carbonate nano-needle array electrodes were grown on carbon cloth by hydrothermal method. The experimental results show that the initial Ni-Co-Fe/CC carbonate electrode has an overpotential of 402 mV, at 10 mA cm-2 current density. The smallest Tafel slope was 72 mV dec-1, and the minimum 畏 10 was 340 MV after immersion in 6 mol L-1 KOH solution for 10 h.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O646;TB383.1

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