▎ 摘　　要

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.