氯化血红素修饰玻碳电极的制备及其作用机理

Preparation of Hemin Modified Glassy Carbon Electrode and Its Interacting Mechanism

以正交法设计实验方案 ,用循环伏安法研究了氯化血红素在玻碳电极上的电化学行为及电催化作用 ,发现 :(1)氯化血红素在电极表面有两种状态 单体和二聚体 ,阴极峰电位分别为 - 0 .2 5± 0 .0 1V和 - 0 .4 3± 0 .0 1V ;(2 )两种状态对过氧化氢均有电催化还原作用 ,单体的催化活性是二聚体的 1.4 5倍 ,并给出了相应的作用机理。以介质转换后Δi2 为指标确定了影响膜稳定性的主要因素为pH ,给出了制备与测试该修饰电极的最佳条件。电催化还原过氧化氢电流与其浓度的线性关系为Δi (A) =3.184 6× 10 -6+2 .6 371× 10 -5C(mmol/L) ;检出限为 1.7× 10 -5mol/L ;相关系数为 0 .992 8。

The electrochemical behavior and electrocatalytic action of hemin modified glassy carbon electrode were studied with orthogonal design by cyclic voltammetry. Two kinds of states of hemin on glassy carbon electrode surface were observed, which were monomer and dimmer, with the cathodic peak potentials of -0.25±0.01 V,-0.43±0.01 V, respectively. They both exhibited good electrocatalytic activity for the reduction of H 2O 2, while the catalytic activity of monomer is by a factor of 1.45 higher than that of dimmer. The relevant interacting mechanism between hemin and H 2O 2 was given. The primary factor of influencing the stability of hemin membrane was pH of the supporting electrolyte according to the catalytic current (Δi) for the reduction of H 2O 2 after medium exchange. The optimal conditions for fabricating and testing hemin modified glassy carbon electrode were obtained by orthogonal design. The linear relationship between the catalytic current for the reduction of H 2O 2 and concentration of H 2O 2 is in the range of 1.7×10 -5 mol/L～1.6×10 -3 mol/L with a correlation coefficient of 0.9928. The detection limit is 1.7×10 -5 mol/L (S/k = 3). The catalytic activity remains well after two weeks, even 28% higher than the initial catalytic activity.