Homogeneous and Heterogeneous Nucleation in Electrocrystallization

The belief amongst most electrochemists that the appropriate models, representing “homogeneous” and “heterogeneous” nucleation in the context of electrocrystallization, are spherical and spherical-cap shapes, respectively, is challenged. A proper foundation for modelling heterogeneous nucleation is introduced. The free energy required for the formation of a nucleus within an indent is derived and compared with that required for the formation of a nucleus onto a flat surface of an electrode. It is shown for the first time, using the classical theory of nucleation, that a much smaller free energy is required for nucleating within an indent on the surface of an electrode than nucleating onto a flat electrode surface. The applicability of the model, with the corresponding equations, to nucleation in the context of electrocrystallization is established.