亚铁氰化钾电催化氧化L-半胱氨酸的电化学行为研究

Electrochemical Oxidation of L-Cys Catalyzed by K_4Fe(CN)_6 at Glassy Carbon Electrode

研究了在0．10mol／L Na2SO4溶液中K4Fe（CN）6在玻碳电极（GCE）上电催化氧化L-半胱氨酸（L-Cys）的电化学行为。在-0．2～0．6V的电位窗口内，L-Cys在GCE上的直接电化学氧化过程迟缓，不易直接发生氧化反应。在K4Fe（CN）6作用下，在0．23V处出现一个不可逆的氧化峰，且氧化峰电流明显增大。研究结果表明，K4Fe（CN）。对L-Cys的氧化具有良好的电催化作用。电催化氧化峰电流Ipa随扫描速度的增大而增大，且与扫描速率平方根（v^1／2）呈线性关系，表明该电催化氧化反应是受扩散控制的电化学过程。催化氧化峰电流与L-Cys浓度在4×10^-5～2×10^-3 mol／L范围内呈良好的线性关系（R=0．9966）。该催化反应过程中电子转移系数a=0．5568，运用计时电流法（CA）得到该电催化氧化的速率常数k为（7．19±0．05）×10^-2（mol／L）^-1·s^-1．

Electrochemical oxidation of L-Cys catalyzed by K4Fe（CN）6 at a glassy carbon electrode （GCE） was investigated by cyclic voltammetry. It was found that no obvious oxidation peak could be obtained at a GCE, which indicated that L-Cys had a high overpotential. However, in the presence of K4Fe（CN）6 a catalytic oxidation peak appeared at 0. 23 V, which indicated that K4Fe（CN）6 could catalyze the electrochemical oxidation of L-Cys. The influence factors on the electrochemical catalytic oxidation were also investigated. The electrochemical catalytic process was diffusion-limited, and the electrode reaction rate constant were determined to be （7.19±0.05）×10^2 （mol/L）^-1·s^-1.