One-pot hydrothermal synthesis of nitrogen-doped reduced graphene oxide for the highly sensitive and simultaneous determination of dihydroxy benzene isomers

Abstract

A simple, one-pot, and short-duration synthetic procedure utilizing two nitrogen sources has been demonstrated to prepare nitrogen-doped reduced graphene oxide (N-RGO). The N-RGO has been hydrothermally synthesized using tetraethylenepentamine (TEPA) and hydrazine hydrate as nitrogen precursors, wherein the latter also functions as an in situ reducing agent. The successful N-doping and other physicochemical properties of N-RGO have been confirmed with various spectroscopic and microscopic techniques. Moreover, a Type-IV adsorption isotherm and 15-fold increment than GR in the surface area of N-RGO with mesoporous structure have been observed. Interestingly, XPS results confirm the presence of a high percentage of pyrrolic-N-atoms in N-RGO. The glassy carbon electrodes modified with N-RGO (N-RGO/GCE) have been utilized for the simultaneous detection of industrial pollutants hydroquinone (HQ) and catechol (CC). The N-RGO/GCE exhibited an excellent electrochemical activity with a peak separation of 110 mV between these isomers. Furthermore, a wide linear range of 1–500 µM with a limit of detection (LOD, 3σ m−1) of 0.038 µM for HQ and 0.026 µM for CC has been observed in 0.1 M PBS (pH 7.07). The practical applicability of the proposed sensor has been evaluated in tap water samples with satisfactory results. The enhanced electrochemical performance of N-RGO has been attributed to its large surface area and facile electron transfer occurring at the defective sites.