Preparation, characterization and amperometric nadh sensor application of free-standing graphene/poly(methylene blue)/silver nanoparticles electrode

In this study, an electrode material was designed for the application of amperometric detection of nicotinamide adenine dinucleotide (NADH). For fabricating electrode material, the certain amounts of methylene blue (MB) solution and silver nanoparticles (AgNPs) suspension were added to synthesized graphene oxide (GO) dispersion to obtain the composite suspension. This composite suspension was filtered through a membrane under vacuum effect to prepare free-standing GO/MB/AgNPs paper. The as-prepared GO/MB/AgNPs paper was immersed into HI solution to convert GO to reduced graphene oxide (rGO) and to obtain rGO/MB/AgNPs paper electrode. rGO/MB/AgNPs paper electrode was used as a working electrode at three-electrode cell to obtain flexible rGO/poly(MB)/AgNPs composite electrode by surface confined electropolymerization of MB which is existing in the composite paper structure. Characterization of this free-standing rGO/poly(MB)/AgNPs composite electrode was carried out by using scanning electron microscopy, scanning tunneling microscopy, X-ray photoelectron spectroscopy, powder X-ray diffraction spectroscopy, Raman spectroscopy, electrochemical impedance spectroscopy, four point probe conductivity measurements and cyclic voltammetry techniques. Flexible rGO/poly(MB)/AgNPs composite electrode was used as a sensor for amperometric dedection of NADH and the sensor demostrated wide linear range, low detection limit, and high sensitivity.