A sensor based on the carbon nanotubes-ionic liquid composite for simultaneous determination of hydroquinone and catechol

MWNTs-IL-Gel/GCE, a glassy carbon electrode modified with multiwalled carbon nanotubes (MWNTs) and ionic liquids (IL), was developed to serve as a sensor for simultaneous determination of Hydroquinone (HQ) and catechol (CC) in this paper. The modified GCE showed two well-defined redox waves for HQ and CC in both CV and DPV with a peak potential separation of ca. 0.1 V, which was large enough for simultaneous detection. The results revealed that the oxidation of HQ and CC with the enhancement of the redox peak current and the decrease of the peak-to-peak separation exhibit excellent electrocatalytic behaviors. A high sensitivity of 1.8 × 10−7 M with detection limits of 6.7 × 10−8 M and 6.0 × 10−8 M (S/N = 3) for HQ and CC were obtained. Moreover, the constants of apparent electron transfer rate of HQ and CC at MWNTs-IL-Gel/GCE were calculated as 7.402 s−1 and 8.179 s−1, respectively, and the adsorption quantity of HQ and CC was 1.408 × 10−6 mol cm−2 with chronocoulometry. The developed sensor can be applied to determinate directly of HQ and CC in aqueous solution.

This DPV response proves that the oxidation of HQ and CC at MWNTs-IL-Gel/GCE occurs at potentials 102 mV and 202 mV independently. The peak currents of HQ and CC increased linearly with the concentration of their own in mixed systems of dihydroxybenzenes.Figure optionsDownload as PowerPoint slideHighlights
► We developed an electrode modified with carbon nanotubes and ionic liquids gel in this paper.
► We use it as a sensor for simultaneous determination of HQ and CC.
► The constant of apparent electron transfer rate between HQ, CC and the modified electrode were obtained.
► The absorption quantity of HQ and CC at the modified electrode was also detected.