Computer simulation of the kinetic behaviour of surface reactions driven by a linear potential sweep: Part III. Monolayer formation by a nucleation and growth mechanism

The kinetic behaviour of a surface process involving the deposition of a two-dimensional surface film by a nucleation and growth mechanism is treated for the case of linear potential sweep control. Features which distinguish nucleation and growth in monolayer formation from random electrodeposition (Langmuir case) treated in previous papers are emphasized. Two main mechanisms are considered: one where the growth occurs from a fixed surface density of nuclei and the other where growth occurs from a potential-dependent density of nuclei. Computer simulations and some analytical derivations of the kinetic behaviour for these two cases are made and the characteristic kinetic features of the process are deduced, enabling the latter to be distinguished in terms of experimentally accessible criteria. The extent of reversibility of the processes can be usefully expressed in terms of a limiting sweep-rate parameter, s₀, which is related to the rate constant for nucleation or the surface density of nuclei and the rate constant for growth.