Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (01): 60-64.doi: 10.3866/PKU.WHXB20030114

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Adsorption and Oxidation of Glycine on Au Film Electrodes in Alkaline Solutions

Zhen Chun-Hua;Fan Chun-Jie;Gu Yan-Juan;Chen Sheng-Pei;Sun Shi-Gang   

  1. State Key Laboratory for Physical Chemistry of Solid Surfaces, Institute of Physical Chemistry, Department of Chemistry, Xiamen University, Xiamen 361005
  • Received:2002-05-27 Revised:2002-08-05 Published:2003-01-15
  • Contact: Sun Shi-Gang

Abstract: Adsorption and oxidation of glycine on electrodes of nanometer scale thin film of gold in alkaline solutions were investigated using in situ FTIR reflection spectroscopy and electrochemical quartz crystal microbalance(EQCM). The FTIRS results demonstrate that the dissociative adsorption of glycine on Au surface can occur at potentials as low as -0.8 V(vs SCE), which leads to produce adsorbed CN- species (cyanide, ~2100 cm-1). When electrode potential is higher than 0.2 V, the adsorbed CN- can be oxidized to OCN-(cyanate, 2169 cm-1); and when the potential is increased further up to 0.3 V, the Au(CN)2- species(gold di-cyanide, 2145 cm-1)appeared as further oxidative species. It has revealed that the electrodeposited nanometer scale thin film of gold on glassy carbon substrate(nm-Au/GC) exhibited AIREs (abnormal infrared effects) for CN- adsorption, which manifested 3 nonlinear IR spectra features: the inversion of the direction of CN- IR band, the enhancement of IR absorption of CN-(about 20 folds) and the increase in the FWHM(full width at half maximum) of CN- IR band. According to EQCM results, the CN- species can adsorb strongly on Au surface and therefore inhibit the adsorption of H2O and OH- species in low potential region. The formation of Au(CN)2- was determined to be the main reason which caused the dramatic loss of surface mass of Au film electrode in a potential scan up to 0.6 V. The current studies are of importance in understanding the interaction between amino acids and Au film electrodes.

Key words: Glycine, Adsorption, Oxidation, in situ FTIRS, Electrochemical quartz crystal microbalance(EQCM), Nanometer scale Au film electrode