Cost-Effective Electrochemical Sensor Based on Carbon Nanotube Modified-Pencil Electrode for the Simultaneous Determination of Hydroquinone and Catechol

In this study, the cost of working electrode was reduced greatly by replacing glassy carbon electrode (GCE) with 2B pencil. The pencil lead was modified with carbon nanotubes (CNTs) for simultaneous and quantitative detection of hydroquinone (HQ) and catechol (CT). The surface morphology of CNT-modified pencil electrode (PE-CNT) was studied by scanning electron microscopy (SEM) whereas electron transfer properties were evaluated through electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). This electrode evinced an enhanced redox reversibility and superior electrocatalytic performance concerning HQ and CT. Consecutive concentration variation studies exhibited linearity in oxidation peak responses up to 300 μM for each of the analytes with a detection limit (S/N = 3) as low as 1.5 and 0.7 μM for HQ and CT, respectively. We proposed a possible mechanism for their sensitive detection. The developed sensor was successfully examined for real sample analysis with tap water and it exhibited a stable and reliable recovery data with high reproducibility. The cost of the 2B pencil is 1000 times lower than that of GCE. Thus, the 2B pencil can be a good alternative to GCE in electrochemical sensor fabrication due to its economic advantage.