THE EFFECT OF CURRENT AND NICKEL NITRATE CONCENTRATION ON THE DEPOSITION OF NICKEL-HYDROXIDE FILMS

An electrochemical quartz crystal nanobalance (EQCN) has been utilized to measure the mass of Ni(OH)(2) films electrochemically deposited fr om Ni(NO3)(2) solutions. The objective of this work was to quantify el ectrochemical deposition as a function of deposition conditions. The c hanging mass recorded on the EQCN was demonstrated to be the result of Ni(OH)(2) deposition. Deposited mass was observed to increase proport ionally with applied charge as suggested by previous investigators. Mo st significantly, the rate of deposition was found to decrease more th an an order of magnitude as the Ni(NO3)(2) concentration increased fro m 0.2 to 2.0M. The effect of concentration is shown to be related to N i(II) concentration as opposed to solution pH or NO3- concentration. A n empirical correlation is given to predict deposition rates in soluti ons ranging from 0.1 to 3.0M Ni(NO3)(2) and at current densities rangi ng from 0.5 to 5.0 mA/cm(2). The decreased deposition rates in concent rated Ni(NO3)(2) are attributed to the formation of intermediate speci es [e.g., NiOH+ or Ni4(OH)(4)(4+)] which diffuse away from the reactio n interface before deposition can occur.