An EQCM study of Sb adsorption and coadsorption with CO on Pt electrode inperchloric acid solutions

Sb adsorption and coadsorption with CO on Pt electrode in perchloric acid s olutions were studied by using cyclic voltammetry and electrochemical quart z crystal microbalance (EQCM). The results demonstrated that Sb adatoms are stable on Pt electrode in the potential range between - 0.25 and 0.50 V (S CE), and that the saturation coverage of Sb is 0.34. Data obtained from the studies of EQCM and programmed cyclic voltammetry shows the number of elec trons transferred in oxidation of Sb-ad on Pt electrode in a positive going potential scan till 0.50 V has been calculated at 3.02 +/- 0.06, and the S b(OH), species were suggested as the adsorbed products of Sb-ad oxidation. At potential higher than 0.50 V the Sb(III) can be oxidized further and wil l desorb progressively from Pt electrode surface. It has been demonstrated that the oxidation of adsorbed and solution CO species on Pt and Pt/Sb-ad e lectrodes undergoes different surface processes. The electrocatalytic effec t of Sb-ad on the oxidation of COad consists mainly of the negatively shift of oxidation potential, i.e. the activation energy of COad oxidation is de creased on a Pt/Sb-ad electrode in comparison to the same reaction carrying out on a Pt electrode. (C) 2000 Elsevier Science Ltd. All rights reserved.