Nucleation in electrochemical growth of the Ag(100) crystal face: determining the nucleus size via the nucleation theorem.
We employ the nucleation theorem for a model-independent determination of the size of the two-dimensional (2D) Ag nucleus with the aid of experimental data for the nucleation-mediated electrochemical growth of the Ag(100) crystal face in aqueous solution of AgNO(3) at 318 K. These data are for the stationary rate of 2D nucleation, for the initial portion of the potentiostatic current transient pertaining to atomically smooth face, and for the galvanostatic current corresponding to stationary growth of the face. It turns out that the 2D nucleus is constituted of 17-64 Ag atoms when the overpotential is in the range of 12-22.4 mV. Upon expressing the overpotential in terms of supersaturation, it is found that the experimental data for the size of the 2D Ag nucleus are in conformity with existing simulation data for the size of the 2D nucleus on the (100) face of Kossel crystal (the simulation nucleus contains 1-30 atoms). It is found as well that the Gibbs-Thomson equation of the classical theory of 2D nucleation describes very well the supersaturation dependence of the size of both the Ag and the simulation nucleus.
Kashchiev
Dimo
D
Institute of Physical Chemistry, Bulgarian Academy of Sciences , ul. Acad. G. Bonchev 11, Sofia 1113, Bulgaria. kash@ipc.bas.bg
Bostanov
Vesselin
V