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

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), -N=N- (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 x 10(-11) mol cm(-2). The pDAB@ERGO/GC film-modified electrode was used successfully for the determination of nitrite ions. The pDAB@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 x 10(-6) to 2.0 x 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.