Electrochemical hydrogen storage by carbon nanotubes decorated with metallic nickel

The electrochemical properties of an electrode of carbon nanotubes decorate d with metallic nickel particles were investigated. A high initial discharg e capacity of 297 mAh g(-1) of the decorated carbon nanotubes was obtained under a discharge current density of 1000 mA/g, after eliminating the capac ity of Ni-P alloy, due to the improvement of the electrocatalytic, activity and the hydrogen adsorption of the surface Ni-P alloy. However, the electr ode of decorated carbon nanotubes was found to show a poor charge/discharge cycle life owing to the dramatic increase of surface reaction resistance m easured by means of electrochemical impedance spectra, which arose probably from destruction of the structure at the interface of the carbon nanotubes and the coating layer and the passivation of nanoscale-size metallic nicke l particles during cycling. (C) 2001 The Electrochemical Society.