Theoretical Analysis of Surface Waves: Revisited

The surface wave for the strongly adsorbed redox spices on electrode is one of the fundamental electrochemical issues, because we don’t need considering the mass transfer of redox species and can calculate voltammogram easily. The ideal voltammogram of the surface wave is symmetric for the forward and the backward scan and it is well known the full-width-at-the-half-maximum (FWHM) is 91 mV. 

 Recently Nieh et al. proposed the potentiometric coulometry based on charge accumulation with a peroxidase/osmium polymer-immobilized electrode for sensitive determination of hydrogen peroxide [1]. In this potentiometric coulometry the peak shape and width of the surface wave is the key point to get the amount of the hydrogen peroxide in the polymer film. Kakutati and Senda [2] and Laviron [3] showed that the interaction between the adsorbed redox species change the FWHM of the surface wave, i.e. the FWHM is decreased (increased) when e(O-O) + e(R-R) – 2e(O-R) < 0 (> 0).

 In this study we have reformulated the chemical potential of the interacting redox species based on Bragg-Williams and Bethe-Guggenheim approximation, and the surface wave voltammogram is evaluated. For the attractive interaction we have found the limiting case that the FWHM become almost zero and the current diverges.　In the Monte Carlo simulation for Kawasaki dynamics system we have confirmed chemical potential obtained by the Bethe-Guggenheim approximation is good enough approximation for the nearest-neighbor interaction model.

 We also proposed that the asymmetry of surface wave voltammogram is due to the counter-ion binding interaction for the redox species.

References

[1] C.-H. Nieh et al. Electrochemistry Communications 33 (2013) 135-137.　    

[2] T. Kakutani and M. Senda, Bull. Chem. Soc. Japan 52 (1979) 3236-3241.

[3] E. Laviron, J. Electroanal. Chem. 100 (1979) 263-270.