INSTABILITY OF NONEQUILIBRIUM FLUCTUATION IN ELECTROCHEMICAL NUCLEATION .2. DETERMINATION OF THE CRITICAL CONDITION

摘要

In the foregoing paper, part I, the mechanism of the fluctuations which are necessarily induced by the breakdown of the electrostatic equilibrium was examined. Consequently, it was found that nonspecific adsorption of ions onto electrode surface is essential to the progress of nucleation. It was also deduced that the critical condition for the unstable growth corresponds to the flat potential distribution in the diffuse layer within the electric double layer. Therefore, using the facts that at the stable region of the fluctuations, the electrode is kept in the electrostatic equilibrium and apparently behaves as an ideal polarized electrode, a method to determine the critical potential by the extrapolation from the stable region was theoretically developed. As a result, the critical potential equations corresponding to the hat distribution of the potential in the diffuse layer were obtained for various experimental conditions. By applying these equations to actual systems, the adsorbed states of ions at the interface can be examined. Therefore, the critical potential for silver nucleation onto platinum electrode in AgNO3+NaNO3 solution were measured. Consequently, no intense specific adsorption of ions was observed, and it was concluded that a pair of Ag+ ion and NO3- ion are simultaneously adsorbed by the electrostatic interaction. (C) 1995 American Institute of Physics. [References: 6]