Electrochemical capacitive studies of cadmium hydroxide nanowires grown on nickel foam

Cd(OH)2 nanowires have been synthesized on nickel foam by a simple template-free growth method. Structural characterization by SEM and TEM indicated that the Cd(OH)2 formed a porous film on the surface of the nickel foam skeletons. The thickness of the film reached approximately 25 μm and the nanowires have diameters of around ∼100 nm. The nanowires is confirmed to be pure phase hexagonal Cd(OH)2 by X-ray diffraction. The electrochemical capacitance behaviors of the Cd(OH)2 nanowires electrode are investigated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy tests. The Cd(OH)2 electrode performed in different electrolyte demonstrates that nanowires possess supercapacitance properties in the presence of high concentration OH− ion. The specific capacitances as high as 1164.8 F g−1 at 1 A g−1 and 257.6 F g−1 at 10 A g−1 are obtained in 6 mol dm−3 KOH solution. The remarkably high capacitance of the Cd(OH)2 nanowire electrode might be attributed to its unique 3D open structure for easy access of electrolyte ions, large surface area and high electrochemical activity. This work demonstrates that Cd(OH)2 nanowires electrode has potential application in electrochemical capacitors.