Electrochemical and in situ spectroelectrochemical studies on the gold nanoparticles co-deposited with cobalt hexacyanoferrate modified electrode and its application in sensor

Abstract

Gold nanoparticles (Au_nano) co-deposited with cobalt hexacyanoferrate (CoHCF) modified electrode was prepared by electrodeposition on glassy carbon electrode (represented as GC/Au_nano~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 Au_nano with CoHCF improved the electrochemical behavior of the Au_nano~CoHCF modified electrode when compared to CoHCF modified electrode. The in-situ spectroelectrochemical changes of Au_nano~CoHCF modified electrode was studied to understand the redox switching of CoHCF in the presence of Au_nano. The in-situ spectral study showed that the codeposited Au_nano 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/Au_nano~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 Au_nano co-deposited with CoHCF (GC/Au_nano~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 Au_nano and poly Au electrode. The GC/Au_nano~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 Au_nano co-deposited with CoHCF clearly showed that the GC/Au_nano~CoHCF electrode could be used as an electrochemical sensor.