Ethanol sensor based on platinum-MWCNT-NiO nanoparticles platform electrode

Reported in this work is a novel electrochemical ethanol sensor that is simple to prepare, cost effective, stable and resistant to intermediates poisoning by using platinum (Pt) electrode modified with multi-walled carbon nanotubes (MWCNT)/NiO nanoparticles. The modified electrode (Pt-MWCNT-NiO) was characterized using field emission transmission electron microscopy (FETEM), x-ray diffraction (XRD), energy dispersive spectroscopy (EDS), Cyclic voltammetry, linear sweep voltammetry and chronoamperometry. The electrode showed the highest ethanol oxidation current compared with the other electrodes studied. Ethanol oxidation current increased with increasing MWCNT-NiO loading on the Pt-MWCNT-NiO electrode. Chronoamperometry analysis gave the lowest limit of detection (LoD) of 1.63 ppm and a sensitivity of 0.01 μAmM ^-1. The catalytic rate constant K _cat and the diffusion coefficient of ethanol on the electrode are 1.94 × 10 ³ cm ³ mol ^-1 s ^-1 and 5.2 × 10 ^-8 cm ²s ^-1 respectively. The high Tafel value of 1227 mVdec ^-1 obtained suggests the involvement of reaction intermediates. However, the repetitive scanning analyses indicates the electrode to be of very high stability (ca 98%), with capacity to withstand poisoning effects of ethanol oxidation products. The analytical data obtained in this study compared well with other studies reported in literature. The lowest LoD (38.8 μM or 1.63 ppm) obtained for chronoamperometry suggest the high sensitivity of this technique over other techniques studied and as such should be considered when constructing the Pt-MWCNT-NiO ethanol sensor for commercial applications.