Potentiodynamic formation of diaminobenzene films on an electrochemically reduced graphene oxide surface: Determination of nitrite in water samples

Highlights: • Novel diaminobenzene film on ERGO was fabricated by potentiodynamic method. • p-DAB@ERGO/GC shows excellent activity towards nitrite. • The proposed sensor exhibits lowest detection limit and wide linear range. • Modified electrode was successfully applied to the analysis in water samples. - Abstract: An electrode comprised of a polydiaminobenzene (p-DAB) film formed on electrochemically reduced graphene oxide (ERGO) on a glassy carbon (GC) (p-DAB@ERGO/GC) was fabricated using a potentiodynamic method for the sensitive and selective determination of nitrite in the presence of a common interference. The p-DAB@ERGO/GC film-modified electrode surfaces were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The film fabrication was initiated via the NH₂ groups of DAB, which was confirmed by XPS from the peaks corresponding to NH (396.7 eV), NH (399.4 eV), NN (400.2 eV), and N⁺H (402.2 eV). The Raman spectra revealed the characteristic D and G bands at 1348 and 1595 cm⁻¹, respectively, which confirmed the fabrication of GO on the GC electrode, and the ratio of the D and G bands was increased after the electrochemical reduction of GO. The surface coverage of the modified electrode was 8.16 × 10⁻¹¹ mol cm⁻². The p-DAB@ERGO/GC film-modified electrode was used successfully for the determination of nitrite ions. The p-DAB@ERGO/GC film-modified electrode exhibited superior activity for the determination of nitrite compared to the bare GC and p-DAB@GC electrodes. The amperometric current increased linearly with increasing nitrite concentration from 7.0 × 10⁻⁶ to 2.0 × 10⁻² M. The detection limit was 30 nM (S/N = 3). In addition, the modified electrode was used successfully to determine the nitrite ion concentration in the presence of a 100-fold excess of common interferents. The practical application of the modified electrode was demonstrated by determining the nitrite ion concentration in water samples.