In situ FTIR spectroscopic investigations of dissociative adsorption and electrooxidation of glycine at the Pt electrode in alkaline solutions
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The dissociative adsorption and electrooxidation of glycine on Pt electrode in 0.1 mol/L NaOH solutions were studied using cyclic voltammetry and in situ FTIR spectroscopy. The results demonstrated that a strong interaction exists between glycine and Pt surface, leading to dissociate easily glycine on Pt surface at potentials below 0.2 V to form cyanide and carboxylate ions, The strongly adsorbed cyanide species on the electrode surface can inhibit the oxidation of glycine, and are considered as poison species for the reaction. The oxidation of glycine at potentials above 0.2 V yielded solution species of cyanate and carboxylate. The cyanide species derived from dissociative adsorption of glycine can be isolated on electrodes of smooth Pt and nanometer thin Pt film supported on glassy carbon(nm-Pt/GC), and has been determined by in situ FTIRS as showing a band at around 2 100 cm(-1). The intensity of IR absorption Land of cyanide on nm-Pt/GC surface is 14 times larger than that on a smooth Pt surface, and the IR band is in the opposite direction to that obtained on Pt surface, confirming the adsorption of cyanide species and the abnormal IR effects. The IR absorption of cyanate and carboxylate produced in the oxidation of glycine yields infrared bands at around 2 169 and 1 390 cm(-1), respectively. The present study revealed the interaction between glycine and Pt electrode surface, and suggested the adsorption modes and oxidation mechanism of glycine on Pt electrode as well.