Cc. Streinz et al., THE EFFECT OF CURRENT AND NICKEL NITRATE CONCENTRATION ON THE DEPOSITION OF NICKEL-HYDROXIDE FILMS, Journal of the Electrochemical Society, 142(4), 1995, pp. 1084-1089
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.