Electrode kinetic measurements with square-wave voltammetry at a constant scan rate

Measuring the Electrode Kinetics of Surface Confined Electrode Reactions at a Constant Scan Rate

“…The corresponding peak potentials for alizarin, vitamin K2 and vitamin B12 are: E p,c = À0.291 V, E p,a = À0.322 V; E p,c = À0.366 V, E p,a = À0.377 V; and E p,c = À0.954 V, E p,a = À0.957 V, respectively. The relative position of voltammetric curves observed under conditions of SWV is opposite compared to the typical cyclic voltammetric pattern of these compounds; the origin of this peculiarity that is typical for surface electrode processes was explained in our previous study [42]. For the experimental conditions corresponding to Figure 1, the forward-to-backward peak current ratio (j I p,c /I p,a j), expressed in absolute current values, is 1.08, 1.35, and 2.08 for alizarin, vitamin K2, and vitamin B12, respectively, reflecting the quasireversible nature of the electrode reactions.…”

“…As previously mentioned, we have recently proposed several strategies for kinetic analysis of electrode processes at a constant scan rate, i.e., at a constant frequency of the potential modulation, by virtue of the amplitude variation only [42]. Here, it is worth recalling that the theory in [42] was developed on the basis of phenomenological ButlerÀVolmer kinetic model.…”

“…Here, it is worth recalling that the theory in [42] was developed on the basis of phenomenological ButlerÀVolmer kinetic model. Recently, Compton et al analyzed surface electrode mechanism by means of asymmetric Marcus-Hush model, demonstrating that the latter can provide kinetic parameters with more clear physical meaning over the phenomenological ButlerÀVolmer model [59].…”

“…On the contrary, we have developed recently a novel electrokinetic methodology [42,43] by utilizing the power of the amplitude of the potential modulation (E sw ), i.e., the height of SW pulses, at a constant scan rate (constant frequency). Taking into account that the amplitude determines the exact potential of the current measurements one realizes that the amplitude is an intrinsic electrokinetic parameter.…”

“…Hence, it has been theoretically predicted that kinetic measurements are possible by alteration of the SW amplitude only, while keeping constant the scan rate of the experiment, which seems to be rather unique approach in voltammetry in general. In this strategy, several experimental approaches are possible, ranging from the analysis of peak potential separation of the split net SW peak in the case of fast surface confined electrode processes [44], through a more general approach in which the peak potential separation between the forward and backward SW components is analyzed [42], up to the analysis of the net SW peak current as a function of the varying amplitude [43].…”