The mass transfer during the nanowire formation by the metal electrodeposition into the pores with a high aspect ratio from a binary electrolyte is studied theoretically. The application of quasi-steady-state approximation is justified. The equations for the ion concentration and electric potential at the bottom and in the mouth of the pores, the reaction overpotential, and the variation of the current density with time are obtained. The problem of time dependence of unfilled pore part length is solved numerically. The distinctions between the results obtained under the potentiostatic and galvanostatic conditions are demonstrated.
A simple model of electrochemical growth of nanowires in the pores of anodic aluminum oxide (AAO) template is developed. The metal deposition is considered at various overpotentials. The model takes into consideration the ionic transfer both in the varying diffusion layer in the pores and in the diffusion layer above the template, which is determined by the external hydrodynamic conditions. The model takes into account the kinetics of electrochemical reaction by means of the Tafel equation and the diffusion transfer of metal cations both in the pores and in the outer diffusion layer. The analytical solution of the problem with several simplifications yields the equations for calculating the time dependence of current, the pore filling time, and other parameters of the process. An example of the application of the model for the analysis of nanowire growth in the template pores is compared with the experimental data showing good agreement.