Decoration of nickel hydroxide nanoparticles onto polypyrrole nanotubes with enhanced electrochemical performance for supercapacitors

A facile and novel method of growing nickel hydroxide nanoparticles on polypyrrole nanotubes (Ni(OH)(2)/PNTs) is presented using methyl orange and ferric chloride formed fibrillar complex as self-degrading tubular template coupled with hydrothermal synthesis. The Ni(OH)(2)/PNT5 samples were characterized by SEM, TEM, FTIR, XRD and XPS. As pseudocapacitors, the obtained Ni(OH)(2)/PNTs in three-electrode configuration display a significantly enhanced specific capacitance (864 Fig at 1 A/g), better rate performance, lower charge-transfer resistance and higher cycling performance (91.1% of the initial capacitance retention at 5 A/g over 2000 cycles) compared to the individual Ni(OH)(2) and PNTs, and previously reported composite electrodes based on Ni(OH)(2) or PNTs. Besides, the symmetric supercapacitors of Ni(OH)(2)/PNTs in two-electrode configuration show a maximum energy density of 18.8 Wh/Kg at the power density of 414.6 W/Kg and a maximum power density of 3.4 kW/kg at the energy density of 8.4 Wh/Kg. The high electrochemical performance of Ni(OH)2/PNT5 can be attributed to the synergistic effect of both components and the unique nanostructure. These encouraging results reveal that the Ni(OH)(2)/PNTs can be used as promising electrode materials for supercapacitors in energy storage. In addition, the method described in this paper provides a generalized route for the construction of transition metal oxides (hydroxides)/PNTs-based composite nanostructures with improved electrochemical performance. (C) 2017 Elsevier B.V. All rights reserved.