Electrochemical Characterisation of the Redox Couple of Fe(II)/Fe(III) Mediated by Nano SiO2 Modified GCE Using Cyclic Voltammetry

A new modified working electrode of glassy carbon electrode with nanoparticles of SiO₂ (SiO₂ nanoparticles/GCE) was prepared by mechanical attachment method. The modified electrode (SiO₂ nanoparticles/GCE) was characterised by electrochemical analysis using cyclic voltammetric technique to evaluate this electrode as nano-sensor. A standard solution of 1 mM K₄[Fe(CN)₆] with 1 M KCl as an electrolyte was used to study the redox current peaks of FeII/FeIII ions on the modified electrode at different concentrations, scan rates, pH, determination of diffusion coefficient (D_f), reliability and stability of the modified electrode. It was found the new nano-sensor (SiO₂ nanoparticles/GCE) had enhancement for the oxidation and reduction current peak of FeII/FeIII ions of about 1.29 and 1.58 µA, respectively. The current ration value of the new modified electrode was Ipa/Ipc = 1.7 with the peak separation of ∆E_pa-c = 140 mV, which demonstrated that the new modified electrode acted in electrolyte as irreversible and heterogeneous reaction, had low detection limit, and enhanced the redox current peaks in acidic pH with good reliability and stability of nanoparticles on the surface of GCE.