酸性介质中Pt电极上α-丙氨酸吸附和氧化的EQCM研究

EQCM Study of Adsorption and Oxidation of α-Alanine on Pt Electrode in Acidic Solution

应用电化学循环伏安和石英晶体微天平 (EQCM)方法研究了 0 1mol/LH2 SO4溶液中α -丙氨酸在Pt电极上的吸附和氧化过程。从电极表面质量变化的结果分析 ,可认为0 1mol/LH2 SO4溶液中正向电位扫描时氢区表面质量的增加是由于水分子取代Had引起的 ,而双电层区的质量增加则是由于H2 O的吸附模式逐渐由氢端吸附转向氧端吸附所致。根据频率变化和电量数据 ,进一步推算出酸性溶液中α -丙氨酸在Pt电极表面只发生弱吸附。H2 O和α -丙氨酸阴离子都可以取代氢吸附在电极表面 ,吸附物种抑制了部分氢的吸附、脱附 ,并影响电极表面质量的改变量 ,而吸附态α -丙氨酸在高电位氧化时会消耗Pt表面的氧 ,本文结果可为认识α -丙氨酸在Pt电极表面过程提供定量的新数据。

The processes of adsorption and oxidation of α-alanine in acidic solution on Pt electrode were studied by using cyclic voltammetry and electrochemical quartz crystal microbalance(EQCM).Quantitative analysis of the mass change on the surface of electrode revealed that the increase of mass in the hydrogen region in a positive-going potential scan is caused by the substitution of water molecule for H ad ,and that in double-layer region it is due to the conversion of binding mode of water from hydrogen-terminal to oxygen-terminal.According to data of the frequency variation and quantity of electricity,α-alanine anion can substitute the adsorbed hydrogen and the adsorbed species can,rastraine the desorption of partial hydrogen and control the changes of mass.The adsorbed α-alanine during its oxidation can consume the adsorbed oxygen.The EQCM study provided quantitative results of surface mass variation during α-alanine oxidation and throw gave a new light in elucidating surface process and reaction mechanism of adsorption and oxidation of small molecule amino acids on Pt electrode.