Adsorption of urea on a polycrystalline silver electrode; comparison of electrochemical and radiometric methods

The adsorption of urea on a polycrystalline silver electrode was studied by radiometry and impedance spectroscopy. The differential capacity of the silver electrode in 0.01 M NaClO₄ solution containing urea in concentrations from 10^–6 to 5×10^–4 M has been determined. The isotherms of urea adsorption, found from the capacitance and radiometric measurements have been compared. The experimental data were described by the Langmuir isotherm, and the Gibbs energy of adsorption was calculated. The urea adsorption takes place in the entire range of the applied potential. The process is reversible with respect to the electrode potential and the bulk urea concentration.Dedicated to Professor Gyorgy Horanyi on the occasion of his 70th birthday