NONEQUILIBRIUM FLUCTUATION THEORY IN ELECTROCHEMICAL NUCLEATION .2. EXPERIMENTAL-DETERMINATION OF CRITICAL FLUCTUATION IN SILVER NUCLEATIONONTO PLATINUM-ELECTRODE
A. Tadano et R. Aogaki, NONEQUILIBRIUM FLUCTUATION THEORY IN ELECTROCHEMICAL NUCLEATION .2. EXPERIMENTAL-DETERMINATION OF CRITICAL FLUCTUATION IN SILVER NUCLEATIONONTO PLATINUM-ELECTRODE, The Journal of chemical physics, 106(14), 1997, pp. 6138-6145
Following part I, in this paper, the experiments for silver nucleation
onto platinum electrode in AgNO3+NaNO3 solution were carried out to c
ompare the theoretical equations with experimental data. The theoretic
al examination predicted that after double layer charging current a mi
nimum current emerges, accompanied with rapid monolayer nucleus format
ion. Since the monolayer nuclei prepare the substrates for the followi
ng extensive nucleation, the stage when the nuclei are formed is of mu
ch importance. From the experiments for double layer charging current,
it was decided that the nucleus formation is activated at the final s
tage of the charging. This result reinforces the theoretical predictio
n that the monolayer nuclei are formed by the minimum current. Extrapo
lation of the minimum current to the critical state gave the critical
autocorrelation distance and the average critical concentration fluctu
ation on the completely active surface. The autocorrelation distance w
as determined as (a) over tilde(cr) = 7.82 x 10(-4) m at 300 K, which
is quite large in comparison with the scale of the fluctuation and in
good agreement with the value obtained in nickel pitting dissolution.
On the other hand, as discussed in the previous paper, since there is
no intense specific adsorption of ions onto the electrode surface, the
electrostatic interaction between the ions accelerates the simultaneo
us adsorption of Ag+ ion and NO3- ion. Therefore, it was concluded tha
t the concentration of the supporting electrolyte NaNO3 also fluctuate
s with the Ag+ ionic concentration. (C) 1997 American Institute of Phy
sics.