Adsorption and Oxidation of Glycine on Au Film Electrodes in Alkaline Solutions
- 化学化工－已发表论文 
运用原位红外反射光谱(insituFTIRS)和电化学石英晶体微天平(EQCM)在分子水平上研究了碱性介质中甘氨酸在纳米金膜电极上的解离吸附和氧化过程.结果表明,甘氨酸在很低的电位下(-0.8V,vsSCE)就可发生解离吸附.其解离产物氰基(CN-)与电极表面存在较强的化学吸附作用,形成AuCN-物种(红外吸收谱峰位于2100cm-1附近).吸附在纳米金膜表面的CN-给出红外吸收显著增强、红外谱峰方向倒反和半峰宽增加的异常红外效应特征.吸附态CN-在低电位抑制H2O和OH-的吸附,当电位高于0.2V可氧化产生OCN-;进一步升高电位到0.3V则形成Au(CN)-2.溶液相物种OCN-和Au(CN)-2对应的红外吸收峰分别为2169cm-1和2145cm-1.实验结果指出,金以Au(CN)-2的形式溶解是导致电极表面质量显著减少的主要原因.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 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 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.