Mg~(2+)-assisted hydrothermal growth of vertically-aligned Ni_3S_2 nanorod bundles on nickel foam for application as binder-free supercapacitor electrodes

摘要

Vertically-aligned Ni~(3)S~(2)nanorod bundles were grown on nickel foam through a novel hydrothermal method for application as supercapacitor electrode. In this method, Fe_(3+)ions were utilized as the etching agent for the nickel foam substrate; the nickel foam itself is both the nickel source for Ni~(3)S~(2)and the scaffold substrate. Furthermore, it was revealed that Mg_(2+)ions can act as growth modifiers and afford vertically-aligned nanorod bundles of Ni~(3)S~(2). A crystal growth mechanism was proposed and the vital roles of Fe_(3+)and Mg_(2+)were explained. Electrochemical studies of the Ni~(3)S~(2)electrodes were conducted in 3 M KOH solution, and the cyclic voltammetric tests revealed that the charge storage of the Ni~(3)S~(2)nanorod bundles involves both capacitive and charge-transfer mechanisms identified by high base currents and broad redox peaks, respectively. A specific capacitance of 230 mF cm_(−2)at a high potential scan rate of 100 mV s_(−1)with a stable performance up to 1000 cycles attests the superiority of the supercapacitor electrode.