Preparation and characterization of carbon nanotubes/methylene blue composite paper electrodes for amperometric detection of nitrite

In this study, surface multi-walled carbon nanotubes (CNTs-Ox) were functionalized by Chemical oxidation method to prepare oxidized CNTs structure (CNTs-Ox). CNTs-Ox dispersions were mixeol with various amount of methylene blue (MB) to prepare composite dispersions (CNTs-Ox/MB). The CNT-Ox and CNTs-Ox/MB dispersions were filtered through a membrane by using vacuum filtration system to obtain CNT-Ox and CNTs-Ox/MB papers. The prepared composite papers reduced by an electrochemical reduction procedure to increase the conductivity of the papers. The prepared electrode materials were characterized by using different techniques such as UV-visible absorption spectroscopy, scanning electron microscopy, energy dispersive X-ray microanalysis, scanning tunneling microscopy, X-ray diffraction, Raman spectroscopy, cyclic voltammetry, chronoamperometry, and four-point probe conductivity measurement techniques. The prepared paper electrodes were successfully performed for the amperometric determination of NO2-. When used for the amperometric detection of nitrite, the CNTs-Ox/MB composite paper electrodes demonstrated a wide linear range, a low detection limit, and high sensitivity.