碳纳米管修饰电极的孔性界面对电分离多巴胺和抗坏血酸的影响

制备了碳纳米管修饰电极(镶嵌、涂层),并研究了电分离多巴胺(DA)和抗坏血酸(AA)的机理.结果表明,该电极的表面有一个多孔性的立体界面层,不仅对DA和AA具有较强的电催化作用,而且二者的氧化峰电位差(ΔE_pa)达250mV以上.用循环伏安法和差示脉冲伏安法研究了影响ΔE_pa的因素.分散剂的种类对ΔE_pa有很大的影响;多层碳纳米管的管径对ΔE_pa的影响较小,碳纳米管的种类(单层、多层、螺旋型多层)则有一定的区别;同一种碳纳米管经不同氧化强度的酸截短后,对ΔE_pa产生了明显影响.这说明修饰电极的界面性质对电分离DA和AA有较大的影响.

Effect of Porous Interfacial Layer of Carbon Nanotube Modified Electrodes on Electrochemical Discrimination of Dopamine from Ascorbic Acid

Modified electrodes were firstly constructed by casting or intercalating carbon nanotube on graphite surface, which resulted in a favorable discrimination of dopamine(DA) and ascorbic acid(AA), and the anodic potential difference(ΔEpa) was more than 250 mV. Taking DA and AA as model compounds, further research on the separation mechanism of these modified electrodes was investigated by employing cyclic voltammetric and differential pulse voltammetric techniques. The results show that the solvent and the surfactant have a strong effect on ΔEpa. Various types of carbon nanotubes(single wall, multi wall or helix multi wall) presented differences of ΔEpa, while the diameter of the same kind of carbon nanotubes proved to have little effect on it. Furthermore, significant change on ΔEpa was observed when carbon nanotube was oxidized by acids with different oxidation capability. All the results showed that the discrimination of DA from AA was mainly attributed to the tubular structure of the nanotubes and its functional group.