Optical and electrochemical study of electrocatalysis by foreign metal adatoms. Oxidation of formic acid on rhodium

Abstract

Specular reflectance spectroscopy, in conjunction with linear potential sweep voltammetry, has been used in studying catalytic effects of Pb and Cd adatoms on the oxidation of HCOOH on Rh. The intermediates formed in that reaction exhibit a similar behaviour as those formed on Pt, thus indicating the same mechanism of reaction on the two metals. The catalytic effect of Pb and Cd adatoms has a dual origin. The adatoms prevent the formation and the adsorption of strongly bound intermediates, as found for Pt electrode. Specular reflectance spectroscopy was used to follow the coverage of foreign metal adatoms in the absence and the presence of the electrode reaction. Different catalytic effects of Pb and Cd adatoms have been attributed to their different adsorbabilities. The adsorption of Pb atoms was unaffected by the presence of HCOOH and its intermediates. However, their presence caused a considerable desorption of Cd adatoms. Certain differences in the voltammograms of Rh electrode in H2SO4 and HClO4 electrolytes were also demonstrated. © 1979 Elsevier Sequoia S.A.