Surface electrochemistry of the oxidation of glycine at Pt

Abstract

The electrochemical oxidation of glycine at a Pt electrode was investigated in aqueous solutions at pH 1 and 13 using steady-state current–potential measurements, cyclic voltammetry, and open circuit potential decay. The capacitance behaviour and the high Tafel slopes suggest the production of free radicals at the surface of the electrode accompanied by a second reaction involving loss of CO2 which is the rate determining step. In the electro-oxidation of glycine, it appears that the adsorbed intermediate species is either hydrolyzed anodically to formaldehyde and ammonia, or is oxidized to a carbonium ion which is subsequently hydrolyzed to formaldehyde and ammonia in solution. This behaviour differs from the dimerization process typical of the radical reactions associated with the Kolbe mechanism. Keywords: glycine, amino acid, electrochemical oxidation, surface electrochemistry, Kolbe mechanism.