Electrochemical reactivity of urea at Pt(100) surface in 0.5 M H2SO4 by AC impedance spectroscopy.

The present paper reports an alternate current impedance spectroscopic study on adsorption of urea (U) at Pt(100) single-crystal surface, examined in 0.5 M H2SO4 supporting electrolyte. The resulted information provided confirmation of the role of electrosorption of urea on the Pt(100) plane through evaluation of the associated charge transfer resistance and capacitance parameters. Obtained impedance results were compared to those previously recorded for guanidinium cation (G+) under analogous experimental conditions, especially with respect to the so-called ion pairing mechanism, as originally proposed for the G+ ion and bi(sulfate)/OH species, based on the voltammetric and in situ Fourier transform infrared spectroscopy results.