pH-controlled morphological structure and electrochemical performances of polyaniline/nickel hexacyanoferrate nanogranules during electrochemical deposition |
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Authors: | Yonghong Wang Yujiao Yang Xiaogang Hao Xinru Zhang Zhonglin Zhang Guozhang Ma |
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Affiliation: | 1. Department of Chemical Engineering, Taiyuan University of Technology, Taiyuan, 030024, China 2. Shanxi Institute of Applied Chemistry, Taiyuan, 030024, China
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Abstract: | To explore the dependences of morphology and electrochemical performance of polyaniline/nickel hexacyanoferrate (PANI/NiHCF) nanogranules on pH value of the reaction system, electrodeposition of PANI/NiHCF nanogranules was performed across a pH range from 0 to 7 on carbon nanotubes (CNTs)-modified platinum substrate by cyclic voltammetry in a mixture of 0.002 mol L?1 NiSO4, 0.25 mol L?1 Na2SO4, 0.002 mol L?1 K3Fe(CN)6, and 0.01 mol L?1 aniline solutions. The morphology and structure of PANI/NiHCF nanogranules were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively. The supercapacitive performances of the nanogranules were investigated with cyclic voltammetry (CV), charge/discharge tests, and electrochemical impedance spectroscopy (EIS). The results showed that the nanogranules with different morphology and sizes were obtained with the change of pH values from 0 to 7, which could control the mechanism of homogeneous or heterogeneous nucleation directly. The nanogranules were dispersed in matrix uniformly at pH 0 and pH 1, while the size of which decreased with the increase of pH values. The smooth cross-linking network structure was found from pH 2 to 7. The structure of PANI/NiHCF nanogranules had slightly changed from pH 0 to 7. PANI/NiHCF nanogranules had good electrochemical performance from pH 0 to 7 in a mixture of 0.5 mol L?1 H2SO4 and 0.5 mol L?1 KNO3 solutions, and the highest specific capacitance value of 274 F g?1 was obtained at current densities of 2 mA cm?2 in neutral medium. PANI/NiHCF nanogranules had high stability in neutral medium after 2,000 cycles by CV. |
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