Modulation of the matrix effect of nafion on tris(bipyridine) ruthenium(II) electrochemical probes by functionalisation with 4-nitrophenylazo graphene-gold nanocomposite

Charge transfer reactions of electroactive reagents in pure Nafion film are generally slow due to Nafion's compact nature and the poor diffusion of ionic species within the film. Cationic reagents, such as tris(bipyridine)ruthenium(II) ion ([Ru(bpy)3]2+), migrate into the electro-inactive hydrophobic region of the ionomer causing a loss in the electrochemical contact of the cationic material with the electrode. A highly dispersive gold nanoparticle (AuNp) dotted 4-nitrophenylazo (NPA) functionalised graphene (G) nanocomposite (AuNp/G/NPA) has been prepared and incorporated into Nafion on a glassy carbon (GC) electrode surface, in order to improve the electroactivity of the cationic reactant within the Nafion film. The Nafion nanocomposite-modified electrode efficiently loaded large amount of [Ru(bpy)3]2+ cationic redox probe. The sensitivity of the functionalised Nafion electrode was determined by the rate at which the Ru2+ sites were regenerated within the film. In comparison to pure Nafion film, the AuNp/G/NPA/Nafion nanocomposite film exhibited 100% relative electroactivity, 30% increase in peak currents and 34.9% reduction in charge transfer resistance.