Electrochemical behaviour of amino acids on Pt(hkl). A voltammetric and insitu FTIR study Part IV. Serine and alanine on Pt(100) and Pt(110)

The electrochemical oxidation of serine and alanine was performed at Pt(100 ) and Pt(110) electrodes and analysed by means of FTIR spectroscopy and cyc lic voltammetry. The open circuit adsorption of both amino acids was also i nvestigated. The oxidation of serine gives rise to the formation of two typ es of strongly adsorbed species, COads coming from the -CH2OH group and CNa ds, which appears as a consequence of the dehydrogenation of the amino grou p. These species can be isolated at the surface of both electrodes during o pen-circuit adsorption experiments. The oxidation of alanine also yields ad sorbed cyanide adlayers on Pt(100) and Pt(110) electrodes. However, the amo unt of adsorbed cyanide formed from this amino acid is much lower than that formed in the case of serine. Thus. the presence of the methyl group bonde d to the alpha carbon atom seems to stabilise the amino acid against its ox idation on both Pt(100) and Pt(110) electrodes. (C) 1999 Elsevier Science S .A. All rights reserved.