Comparative Study of Screen-Printed Electrodes Modified with Graphene Oxides Reduced by a Constant Current

Abstract

A comparative study of several screen-printed electrodes modified with electrochemically reduced graphene oxides (ERGO) by means of a constant current has been carried out. The ERGOs were produced from graphene oxides (GO) with different controlled functional groups contents and locations. The experimental reduction conditions were optimized for each particular GO to generate ERGO-modified electrodes with the aim of improving the performance of the dopamine redox process. The ERGO-modified electrodes exhibited a larger electroactive area, a higher reversibility of the redox process, faster kinetics, and greater double-layer capacitance. Analysis of the reduction degree and residual functional groups by means of X-ray photoelectron spectroscopy (XPS) after and before reduction enabled us to determine the relation between the electrochemical behavior and morphology of the electrodes. A hydrazine-reduced graphene oxide showed the best analytical performance with a higher sensitivity (0.259 μA/μM vs. 0.090 μA/μM in the case of a bare electrode), and a linear range from 1–100 μM. It was found that both the experimental reduction conditions and starting graphene material are critical for obtaining a modified electrode with a suitable electrochemical behavior and properties and that a constant current is a suitable technique for the reduction of graphene oxides, especially for screen-printed electrodes.