THE ELECTROCHEMISTRY OF NITROGEN-CONTAINING COMPOUNDS AT PLATINUM SINGLE-CRYSTAL ELECTRODES - PART-2 - SEMICARBAZIDE ON PT(100) ELECTRODES

The electrochemical behaviour of Pt(100) electrodes immersed in semica rbazide containing acidic solutions has been studied by means of cycli c voltammetry and in situ FTIR spectroscopy. Various adsorbed and solu tion intermediates have been detected spectroscopically in the potenti al range between 0.10 and 1.20 V RHE. Adsorbed CO, both linearly-and b ridge-bonded, is formed upon the dissociative adsorption of semicarbaz ide for potentials above 0.25 V RHE. This seems to be the main path fo r the oxidation of semicarbazide to CO2 and molecular nitrogen. Other reaction paths involve the formation of urea and nitric oxide. These s pecies have been detected in the adsorbed state for potentials between 0.50 and 0.90 V. The in situ infrared spectra also show bands in the C=N stretching region which have been tentatively assigned to the form ation of cyanamide and adsorbed cyanate anions. (C) 1997 Elsevier Scie nce S.A.