Abstract
In this work, MnO2 was electrodeposited onto arrayed carbon nanotubes (CNTs), and the morphology and electrochemical properties of as-formed MnO2/CNT nanocomposite materials were systematically investigated. The experiments began with atmospheric chemical vapor deposition of aligned CNTs onto a Ti current collector, followed by hydrophilic treatment in HNO3 solution and anodic galvanostatic deposition of MnO2 from 0.01 M Mn(CH3COO)2．4H2O under pH = 2.0 and pH = 7.0. With different deposition times (60-7200 s) and plating currents (0.1 mA, 1.0 mA, 5.0 mA), the microstructure, morphology and supercapacitive performance of nanocomposite electrodes were characterized using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy. Electrochemical measurements reveal two optimum deposition conditions, namely, pH = 2.0, I = 1.0 mA, t = 120 s and pH = 7.0, I = 0.1 mA, t = 1200 s. The resulting nanocomposite electrodes have achieved an overall specific capacitance (SC) of 198 and 190 F/g at 10 mV/s, and 86 and 95 F/g at 1000 mV/s, respectively, and operation stability (3000 cycles). The results indicate arrayed CNT-MnO2 nanocomposites are promising electrode materials for supercapacitors.