Electrochemical and <I>In Situ</I> Spectroelectrochemical Studies on the Gold Nanoparticles Co-Deposited with Cobalt Hexacyanoferrate Modified Electrode and Its Application in Sensor

Abstract

Gold nanoparticles (Aunano) co-deposited with cobalt hexacyanoferrate (CoHCF) modified electrode was prepared by electrodeposition on glassy carbon electrode (represented as GC/Aunano-CoHCF) and characterized. The surface morphology of the modified electrode was studied by AFM and the electrochemical properties were studied by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The co-deposition of Aunano with CoHCF improved the electrochemical behavior of the Aunano-CoHCF modified electrode when compared to CoHCF modified electrode. The in-situ spectroelectrochemical changes of Aunano-CoHCF modified electrode was studied to understand the redox switching of CoHCF in the presence of Aunano. The in-situ spectral study showed that the co-deposited Aunano with CoHCF acted as nanoelectrode and improved the electron transfer and redox switching processes when compared to CoHCF modified electrode. An enhanced electrocatalytic oxidation of hydrogen peroxide (H2O2) was observed at the GC/Aunano-CoHCF electrode with an onset potential of 0.5 V when compared to GC/CoHCF electrode. The poly Au electrode did not show a similar oxidation peak for H2O2 oxidation. The Aunano co-deposited with CoHCF (GC/Aunano-CoHCF) significantly enhanced the electrocatalytic property of CoHCF. The amperometric detection of H2O2 was studied at the CoHCF modified electrode in the presence and absence of Aunano and poly Au electrode. The GC/Aunano-CoHCF electrode showed fast sensing response and lower detection limit for H2O2 when compared to GC/CoHCF and poly Au electrode. The electrochemical, in situ spectroelectrochemical and electrocatalytic properties of Aunano co-deposited with CoHCF clearly showed that the GC/Aunano-CoHCF electrode could be used as an electrochemical sensor.