Electrochemical studies of NADH oxidation on chemically reduced graphene oxide nanosheets modified glassy carbon electrode
Electrochemical studies of NADH oxidation on chemically reduced graphene oxide nanosheets modified glassy carbon electrode
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DOI：
10.1016/j.matchemphys.2020.123015
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发表时间：
2020-07-15
影响因子：
4.6
通讯作者：
Sivasubramanian, R.
中科院分区：
文献类型：
--
作者：
Immanuel, Susan;Sivasubramanian, R.
在本研究中，利用各种电化学技术研究了NADH在化学还原氧化石墨烯修饰的玻碳电极（GCE）上的电化学氧化。采用改进Hummer法制备CRGO，并分别采用透射电镜（TEM）、x射线衍射（XRD）、拉曼光谱（Raman spectroscopy）、傅立叶变换红外光谱（FTIR）和紫外可见光谱（UV-vis spectroscopy）对CRGO进行了表征。透射电镜研究发现纳米片的存在，并通过红外光谱证实了残余官能团的掺入。拉曼分析表明，CRGO纳米片对应的D和G波段存在蓝移。从I-D/I-G比值可以看出，与氧化石墨烯相比，CRGO具有较高的缺陷。最初的电化学研究使用循环伏安法进行，与GO/GCE和裸GCE相比，CRGO/GCE表现出低过电位和高氧化电流。动力学研究表明，氧化反应为吸附控制反应，并用流体动力学伏安法测定了电子转移数。此外，在不同电位下进行了EIS分析，以研究电极/电解质界面的电荷转移动力学。随着施加电位从双层区向法拉第区变化，电荷传递电阻减小，表明NADH在相应电位处发生氧化。此外，双层电容的减小证实了反应产物的吸附导致电极表面结垢。采用差分脉冲伏安法（DPV）检测CRGO/GCE上的NADH。检测限为21.85 μ M，线性范围为50 μ M-650 μ M。结果表明，CRGO活性优于GO，但其电子传递动力学很差，存在电极结垢问题。
In this study, the electrochemical oxidation of NADH was investigated on chemically reduced graphene oxide (CRGO) modified glassy carbon electrode (GCE) using various electrochemical techniques. CRGO was prepared by modified Hummer's method and characterized using transmission electron microscope (TEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) and UV-vis spectroscopy respectively. The TEM studies revealed the presence of nanosheets and the incorporation of residual functional group was confirmed through FTIR spectroscopy. Raman analysis showed the corresponding D and G band with a blue shift for CRGO nanosheets. Also the CRGO showed high defect compared to GO as elucidated from I-D/I-G ratio. The initial electrochemical studies were carried out using cyclic voltammetry wherein the CRGO/GCE exhibited low overpotential and high oxidation current compared to GO/GCE and bare GCE. Kinetic studies revealed that the oxidation is an adsorption controlled reaction and the number of electron transfer was determined using hydrodynamic voltammetry. Further, the EIS analysis was carried out at various potentials to study the charge transfer kinetics at the electrode/electrolyte interface. As the applied potential is varied from the double layer to Faradaic region, the charge transfer resistance decreases which indicates the NADH oxidation at the corresponding potential. Also, the decrease in the double layer capacitance confirms the adsorption of reaction products leading to fouling of the electrode surface. The detection of NADH on CRGO/GCE was performed using differential pulse voltammetry (DPV). The limit of detection was found to be 21.85 mu M with a linear range of 50 mu M-650 mu M. It is found that CRGO showed better activity compared to GO but their electron transfer kinetics is very poor and suffered from electrode fouling.