The asymmetric model has previously been used to explain deviations from the symmetric MH model observed for solution-phase redox systems [E. Laborda, M.C. Henstridge, R.G. Compton, J. Electroanal. Chem. 667 (2012) 48-53] by taking into account inner-shell differences between the oxidised and reduced species. We extend the theory to the description of electron transfer reactions of surface-bound species and examine several experimental features for both cyclic and square wave voltammetry, as well as Tafel plots, using both symmetric and asymmetric Marcus-Hush models and the phenomenological Butler-Volmer model.
The asymmetric MH model is seen to outperform the other models in terms of the quantitative description of the full voltammetric waveshape and is able to reproduce all of the experimental trends examined, as such its use for the analysis of surface-bound redox couples is highly recommended.