ZnO@MnO2 nanocomposite modified carbon paste electrode for electrochemical detection of dopamine

Abstract

In this study, we have compared the performance of a bare carbon paste electrode (BCPE) against the ZnO@MnO2 nanocomposite modified carbon paste electrode (MCPE) in the electrochemical determination of dopamine (DA). Chemical and structural features of the ZnO@MnO2 nanocomposites were characterized using scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDX), transmission electron microscopy (TEM), X-Ray diffraction (XRD), thermo-gravimetric analysis (TGA) with differential thermal Analysis (DTA) and Brunauer-Emmet-Teller (BET) surface area analysis. The cyclic voltammetry (CV) measurement of the ZnO@MnO2 nanocomposite MCPE showed better oxidative catalytic activity (3.6 μA) towards the DA than BCPE with higher efficiency (44.50%) in sensing the dopamine, making MCPE suitable for developing biosensors. The electrochemical studies were carried out in 5 × 10−5 M DA and obtained results were measured in the potential range of −0.2 to 0.6 V vs. saturated calomel electrode (SCE). The electrochemical performance of electrochemical impedance spectroscopy (EIS) and Tafel technique were measured for the BCPE and MCPE using 0.2 M phosphate buffer to maintain pH 7.2 with the scan rate of 50 mV/s. The redox peak current for MCPE Vs scan rate had good linearity with correlation coefficients of R2 = 0.9996, which represents the diffusion controlled process was under controlled electron transfer reaction. It is expected that the good electrocatalytic behavior of MCPE can be utilized for the fabrication of biosensors.

Keywords

• Dopamine
• Nanocomposites
• Modified carbon paste electrode
• Cyclic voltammetry