Preparation of Free-Standing and Flexible Graphene/Ag Nanoparticles/Poly(pyronin Y) Hybrid Paper Electrode for Amperometric Determination of Nitrite.

A flexible and free-standing graphene-based hybrid paper was successfully fabricated by successive applications of vacuum filtration and electropolymerization. First, a suspension including graphene oxide (GO) and silver nanoparticles (AgNPs) was prepared, and GO/AgNPs paper was obtained by vacuum-filtration of this suspension through a membrane. This GO/AgNPs paper was transformed to rGO/AgNPs paper by using both chemical reduction with HI and thermal annealing procedures. rGO/AgNPs/poly(PyY) hybrid paper electrode was formed by electropolymerization of Pyronin Y (PyY) on rGO/AgNPs paper electrode from a PyY monomer-containing (pH 1.0) solution. Structural, chemical, and morphological characterization of this hybrid paper was carried out by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy, infrared spectroscopy, UV-vis absorption spectroscopy, four-point probe conductivity measurement, and cyclic voltammetry techniques. Electrooxidation of nitrite on rGO/AgNPs/poly(PyY) hybrid paper electrode has been achieved at 860 mV with a linear range of 0.1-1000 μM, sensitivity of 13.5 μAμM(-1)cm(-2), and a detection limit of 0.012 μM. Amperometry studies have shown that the hybrid paper electrode is suitable for amperometric determination of nitrite in both standard laboratory samples and real samples. Moreover, this paper electrode selectively detects nitrite even in the presence of 100-fold common ions and exhibits an excellent operational stability and good flexibility.