Characterization of honeycomb-like "β-Ni(OH)2" thin films synthesized by chemical bath deposition method and their supercapacitor application

Nanostructured nickel hydroxide thin films are synthesized via a simple chemical bath deposition (CBD) method using nickel nitrate Ni(NO3)(2) as the starting material. The deposition process is based on the thermal decomposition of ammonia-complexed nickel ions at 333 K. The structural, surface morphological, optical, electrical and electrochemical properties of the films are examined. The nanocrystalline "beta" phase of Ni(OH)(2) is con firmed by the X-ray diffraction analysis. Scanning electron microscopy reveals a macroporous and interconnected honeycomb-like morphology. Optical absorption studies show that "beta-Ni(OH)(2)" has a wide optical band-gap of 3.95 eV. The negative temperature coefficient of the electrical resistance of "beta-Ni(OH)(2)", is attributed to the semiconducting nature of the material. The electrochemical properties of "beta-Ni(OH)(2)" in KOH electrolyte are examined by cyclic voltammetric (CV) measurements. The scan-rate dependent voltammograms demonstrate pseudocapacitive behaviour when "beta-Ni(OH)(2)" is employed as a working electrode in a three-electrode electrochemical cell containing 2 M KOH electrolyte with a platinum counter electrode and a saturated calomel reference electrodes. A specific capacitance of similar to 398 x 10(3) F kg(-1) is obtained. (C) 2009 Published by Elsevier B.V.