Metal Nanowires Subjected to Relavant Hydrated Metal Ions

Abstract

The hcp-Co and fcc-Ni nanowires with the diameter of ~ 50nm were successfully prepared at different overpotentials by using potentiostatic electrochemical deposition in the pores of AAO templates. The prepared nanowires were characterized by X-ray diffraction, and the morphology of the nanowires was investigated by scanning electron microscope. In this study a new way is established to understand the growth rate of nanowires. The effect of work function on the growth rate of Co and Ni nanowires having same electrolyte’s concentration, same pH value, and same overpotentials, has been discussed. The growth rate of metal nanowires in ECD is determined by the tunneling current between a metal and hydrated metal ions. The higher the tunneling current, the higher will be the growth rate. The tunneling current probably relates to the work function of metal. The larger is the value of work function the lower is the probability of electron tunneling. Lowering the work function causes increase in the current density. The hydrated Co and Ni ions are of octahedral structure with M-O distance of 2.08 A and 2.05 A, respectively. The work function of Co is smaller, this lead to higher tunneling current density. Therefore, the measured current density is higher for Co than for Ni and the Co nanowires grow faster than that of the Ni nanowires.