High Yield Submicron/Nano Carbon from Boropukuria Coal as Electrochemical Sensing Material for Hydroquinone and Catechol: Kinetic and Mechanistic Studies

A sub-micron/nano carbon (CC) material derived from Boropukuria coal via pyrolysis followed by ball milling method was used to modify a glassy carbon electrode (GCE) for detecting hydroquinone (HQ) and catechol (CT). Various characterization techniques, such as field-emission scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy were employed to study the CC material. The modified electrode (CC-GCE) exhibited excellent electrocatalytic activity in 0.1 M PBS (pH 7.0), resolving HQ and CT redox peaks in cyclic voltammetry and differential pulse voltammetry due to differing catalytic effects. Kinetic studies revealed heterogeneous electron transfer rate constants (k_s) of 0.51 cm s⁻¹ (HQ) and 0.72 cm s⁻¹ (CT), with activation energies of 9.23 kJ mol⁻¹ (HQ) and 10.81 kJ mol⁻¹ (CT). A possible reaction mechanism was proposed based on pH, scan rate, and H-bonding effects. The sensor showed a linear range of 5-250 μM, with detection limits of 0.067 μM (HQ) and 0.089 μM (CT), and was successfully applied to tap water analysis. The CC-GCE electrode also demonstrated good reproducibility and stability, emphasizing its potential for diverse analytical applications on real samples.