Authors: Justus Masa Christopher BatchelorMcAuley Wolfgang Schuhmann Richard G Compton
Publish Date: 2013/10/16
Volume: 7, Issue: 1, Pages: 71-78
Abstract
The application of naive KouteckyLevich analysis to micro and nanoparticle modified rotating disk electrodes of partially covered and nonplanar geometry is critically analysed Assuming strong overlap of the diffusion fields of the particles such that transport to the entire surface is timeindependent and onedimensional the observed voltammetric response reflects an apparent electrochemical rate constant k app o equal to the true rate constant k o describing the redox reaction of interest on the surface of the nanoparticles and the ratio ψ of the total electroactive surface area to the geometric area of the rotating disk surface It is demonstrated that KouteckyLevich analysis is applicable and yields the expected plots of I −1 versus ω −1 where I is the current and ω is the rotation speed but that the values of the electrochemical rate constants inferred are thereof k app o not k o Thus for ψ 1 apparent electrocatalysis might be naively but wrongly inferred whereas for ψ 1 the deduced electrochemical rate constant will be less than k o Moreover the effect of ψ on the observed rotating disk electrode voltammograms is significant signalling the need for care in the overly simplistic application of KouteckyLevich analysis to modified rotating electrodes as is commonly applied for example in the analysis of possible oxygen reduction catalysts
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