Poly(malachite green) at nafion doped multi-walled carbon nanotube composite film for simple aliphatic alcohols sensor

Abstract

Conductive composite film which contains nafion (NF) doped multi-walled carbon nanotubes (MWCNTs) along with the incorporation of poly(malachite green) (PMG) has been synthesized on glassy carbon electrode (GCE), gold and indium tin oxide (ITO) electrodes by potentiostatic methods. The presence of MWCNTs in the composite film (MWCNTs–NF–PMG) enhances surface coverage concentration ( Γ) of PMG to ≈396%, and increases the electron transfer rate constant ( k s) to ≈305%. Similarly, electrochemical quartz crystal microbalance study reveals the enhancement in the deposition of PMG at MWCNTs-NF film. The surface morphology of the composite film deposited on ITO electrode has been studied using scanning electron microscopy (SEM) and scanning tunneling microscopy (STM). These two techniques reveal that the PMG incorporated on MWCNTs–NF film. The MWCNTs–NF–PMG composite film also exhibits promising enhanced electrocatalytic activity towards the simple aliphatic alcohols such as methanol, ethanol and propanol. The electroanalytical responses of analytes at NF–PMG and MWCNTs–NF–PMG films were measured using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). From electroanalytical studies, well defined voltammetric peaks have been obtained at MWCNTs–NF–PMG composite film for methanol, ethanol and propanol at Epa = 609, 614 and 602 mV respectively. The sensitivity of MWCNTs–NF–PMG composite film towards methanol, ethanol and propanol in CV technique are 0.59, 0.36 and 0.92 μA mM −1 cm −2 respectively, which are higher than NF–PMG film. Further, the sensitivity values obtained using DPV are higher than the values obtained using CV technique.