【摘要】 以现场长光程薄层圆二色光谱电化学方法研究了抗坏血酸在玻碳电极上的电极反应过程.通过双对数法和非线性回归的方法处理了薄层圆二色光谱电化学实验数据,结果表明抗坏血酸在pH7.0的缓冲溶液中玻碳电极上为2个电子转移的不可逆电化学氧化,氧化产物在电极上发生了强吸附,吸附层对抗坏血酸的电化学氧化反应有自加速作用,并获得了抗坏血酸在探电极和在吸附电极上的式电位分别为E^?=0.09V,E^?=0.26V;电子转移数和电子转移系数分别为an=0.41,a_?n=0.07;标准复相电子转移速率常数分别为k⁰=8.0×10^-5cm s^-1,k⁰_a=1.9×10^-4cm s^-1;吸附系数为β=102.6±0.2.更多还原

【Abstract】 The electrode reaction process of ascorbic (Vc) was studied by in-situ circular dichroic( CD) spectroelectrochemistry with a long optical path thin layer cell on glassy carbon (GC) electrode. The spectroelectrochemical data were analyzed by the double logarithmic method together with nonlinear regression. The results suggested that the mechanism of Vc in pH 7.0 phosphate buffer solution at GC electrode was a two-electron irreversible electrooxidation followed by adsorption of the oxidation product. That is a self-accelerated process. Some kinetic parameters at free and at adsorbed electrode surface, i.e. the formal potentials, E0 = 0.09 V, Ea0’ - 0.26 × 0.02 V; the electron transfer coefficient and number of transfered electron, an=0.41,aan=0.07;the standard heterogeneous electron transfer rate constant, k0 = 8.0 × 10-5 cm·s-1, ka0 = 1.9×10-4 cm·s-1 and adsorption constant, β= 102.6 were also estimated.更多还原