Fabrication of free-standing reduced graphene oxide composite papers doped with different dyes and comparison of their electrochemical performance for electrocatalytical oxidation of nitrite.

Free-standing graphene composite papers exhibit very high flexibility and stability. Therefore, these materials are preferred as modular electrodes for some electrochemical applications, e.g. electrochemical sensors, supercapacitors, and batteries. Graphene composite papers are usually doped with different substances to improve their electrical conductivity, electrochemical performance, and stability. This work describes the fabrication of flexible and free-standing reduced graphene oxide (rGO) papers doped with phenazine, phenothiazine, phenoxazine, xanthene, acridine, and thiazole class of dye molecules. Fabrication procedure was applied by two basic steps: vacuum filtration of a dispersion containing GO sheets and dye molecule through a membrane and reduction of free-standing GO/dye paper to rGO/dye paper by treatment with hydriodic acid. Characterization of these rGO/dye papers were achieved by using scanning electron microscopy, scanning tunneling microscopy, energy dispersive X-ray analysis, powder X-ray diffraction spectroscopy, Raman spectroscopy, fourier transform infrared spectroscopy, UV–vis. absorption spectroscopy, four-point probe conductivity measurement and cyclic voltammetry techniques. Electrical conductivity and electrochemical performance studies indicated that acriflavine (Acr) doped rGO paper electrode exhibited the best performance for electrocatalytical oxidation of nitrite. When rGO/dye paper was applied as amperometric sensor for nitrite, the sensor was very stable, flexible, and reproducible. rGO/Acr paper demonstrated good quality parameters with sensitivity of 0.40 μAμM −1 cm −2 , detection limit of 0.12 μM, and linear range of 0.40–3600 μM. [ABSTRACT FROM AUTHOR]