Electrochemical studies of two diphenols isomers at graphene nanosheet–poly(4-vinyl pyridine) composite modified electrode

A voltammetric sensor for hydroquinone (HQ) and catechol (CC) was developed. This was realized by modifying a glassy carbon electrode with composite film of graphene nanosheet and poly(4–vinylpyridine) (GR–P4VP/GCE). The smaller peak potential separation (ΔEp) of the GR-P4VP/GCE indicates the electrode process is very reversible as a result of increase in kinetics of electron transfer as and when P4VP was present in the modified electrode as compared to the GR/GCE and bare GCE. The proposed electrode has displayed a synergistic effect of P4VP and GR on the electrocatalytic oxidation of CC and HQ in sodium sulphate buffer solution (pH 2.5). The anodic peak potential, Epa, of both were clearly resolved in either cyclic voltammetry or differential pulse voltammetry which made simultaneous determination of both compounds possible. The GR–P4VP/GCE has exhibited excellent sensitivities in the measurement of HQ and CC with detection limits of 8.1 nM and 26 nM, respectively. The GR–P4VP/GCE developed was not interfered by traditional interferences, viz. phenol, nitrophenol, aminophenols, bisphenol A and chlorophenols. The GR–P4VP/GCE was successfully applied for simultaneous detection of spikes HQ and CC in tap water and lake water with encouraging results.