Electrochemical behaviour of amino acids on Pt(hkl): a voltammetric and in situ FTIR study. Part IV. Serine and alanine on Pt(100) and Pt(110)

Abstract

The electrochemical oxidation of serine and alanine was performed at Pt(100) and Pt(110) electrodes and analysed by means of FTIR spectroscopy and cyclic voltammetry. The open circuit adsorption of both amino acids was also investigated. The oxidation of serine gives rise to the formation of two types of strongly adsorbed species, COads coming from the -CH2OH group and CNads, which appears as a consequence of the dehydrogenation of the amino group. These species can be isolated at the surface of both electrodes during open-circuit adsorption experiments. The oxidation of alanine also yields adsorbed cyanide adlayers on Pt(100) and Pt(110) electrodes. However, the amount 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 bonded to the alpha carbon atom seems to stabilise the amino acid against its oxidation on both Pt(100) and Pt(110) electrodes.