Nanoscale morphology dependent pseudocapacitance of NiO: Influence of intercalating anions during synthesis.
Nanoscale morphology dependent pseudocapacitance of NiO: Influence of intercalating anions during synthesis.
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DOI：
10.1039/c0nr00555j
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发表时间：
2011-02
期刊：
影响因子：
6.7
通讯作者：
S. Meher;P. Justin;G. R. Rao
中科院分区：
文献类型：
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作者：
S. Meher;P. Justin;G. R. Rao
以十六烷基三甲基溴化铵（CTAB）为模板剂，尿素为水解控制剂，采用水热法在均匀沉淀条件下制备了3种高比表面积的纳米多孔NiO样品。本研究是为了确定不同的阴离子（乙酸根，硝酸根和氯离子）存在于前体盐的NiO的形态和赝电容行为的影响。采用热重分析（TG）、差示扫描量热分析（DSC）、粉末X射线衍射（PXRD）、BET和场发射扫描电子显微镜（FESEM）对样品进行了表征。通过循环伏安法、恒电流充放电循环（计时电位法）和交流阻抗谱技术，研究了不同层次的NiO表面形貌及其对电化学赝电容行为的影响。通过NO3-离子插层法制备的NiO样品具有较高的比表面积、中等的孔隙率和表面附着有纳米线的新型松果状形貌。该样品在5 mV s（-1）的扫描速率下表现出最高的赝电容279 F g（-1），由循环伏安法测量计算。Cl-插层法制备的样品具有较低的比表面积、孔隙率和赝电容行为，呈纳米花状形貌。在CH 3COO-离子存在下制备的NiO样品显示出蜂窝型表面形貌，具有中等的赝电容值，但具有较高的可逆性。这些NiO电极上的恒电流充放电和阻抗谱测量与CV结果一致。在100次恒电流充放电循环后，发现所有三种NiO样品的库仑效率都很高（85%至99%）。研究表明，前驱体盐中的阴离子对NiO的表面形貌和孔隙率有很大的影响，进而对NiO粉体的赝电容行为和功率性能有很大的影响。
Three nano-porous NiO samples with high specific surface area were prepared by a simple hydrothermal method under homogeneous precipitation conditions using CTAB as a template and urea as the hydrolysis controlling agent. This study was done to determine the effect of different anions (acetate, nitrate and chloride) present in the precursor salts on the morphology and pseudocapacitance behavior of NiO. The samples were characterized by thermogravimetry (TG), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), Brunauer-Emmet-Teller (BET) isotherm and field emission scanning electron microscopy (FESEM). The final NiO samples showed different hierarchical surface morphologies and their effect on the electrochemical pseudocapacitance behavior was carefully studied by cyclic voltammetry, galvanostatic charge-discharge cycles (chronopotentiometry) and impedance spectroscopic techniques. The specific capacitance of NiO sample synthesized by NO3- ion intercalation showed higher surface area, intermediate porosity and a novel pine-cone morphology with nano-wire surface attachments. This sample exhibits the highest pseudocapacitance of 279 F g(-1) at a scan rate of 5 mV s(-1), calculated from the cyclic voltammetry measurements. The sample synthesized by Cl- intercalation shows a nano-flower morphology with lower surface area, porosity and pseudocapacitance behaviour. The NiO sample prepared in the presence of CH3COO- ions showed a honeycomb type surface morphology with an intermediate pseudocapacitance value but higher reversibility. The galvanostatic charge-discharge and impedance spectroscopic measurements on these NiO electrodes were consistent with CV results. The Coulombic efficiency of all the three NiO samples was found to be high (∼85 to ∼99%) after 100 galvanostatic charge-discharge cycles. This study shows that the surface morphology and porosity of NiO are strongly influenced by the anions in the precursor salts, and in turn affect significantly the pseudocapacitance behavior and the power performance of NiO powders.