Abstract
In the theoretical treatment of heterogeneous electron transfer rate constant, k(o), the expression for the rate constant is considered as a composite of two parts: a dynamical pre-exponential one, the other the activation barrier (exponential) part. The pre-exponential part has been treated through several models: the collision frequency, the precursor- equilibrium and the Khan models. In this work, a simple alternative approach based on random walk model is proposed. The advantage of this random walk model is that all the parameters in it are either experimentally measurable or can be easily calculated. The result of calculation shows it to be far superior to collision frequency model, even better than precursor-equilibrium model and comparable to Khan model.