Electrodeposited Ni-Fe onto Glassy Carbon for the Detection of Methylene Blue

Abstract

A composite electrode composed of electrodeposited, nickel-iron nanostructured clusters onto a glassy carbon (GC) disk electrode was used as a working electrode to detect methylene blue at concentrations below 10 μM. The Ni-Fe clusters were prepared by pulse electrodeposition and a lateral composition variation was observed reflective of a local pH change across the Ni-Fe feature. The applied potential for the detection of MB at a pH of 4 was determined through voltammetry, and demonstrated using chronoamperometry and electrochemical impedance spectroscopy (EIS). The adsorption of MB influenced both the capacitance, C, and ohmic resistance, R s . A peak present in i t 1 / 2 vs t chronoamperometry plots decreased with lower MB bulk concentration, while in contrast, the RsC parameters determined from equivalent circuit models of EIS had the opposite behavior having a larger signal with lower MB concentration, and hence providing a way to increase the detection signal at lower MB concentration.