Electrochemically reduced graphene oxide with enhanced electrocatalytic activity toward tetracycline detection

Abstract

An electrochemically reduced graphene oxide sample, ERGO-0.8V, was prepared by electrochemical reduction of graphene oxide (GO) at –0.8 V, which shows unique electrocatalytic activity toward tetracycline (TTC) detection compared to the ERGO-1.2V (GO applied to a negative potential of –1.2 V), GO, chemically reduced GO (CRGO)-modified glassy carbon electrode (GC) and bare GC electrodes. The redox peaks of TTC on an ERGO-0.8V-modified glass carbon electrode (GC/ERGO-0.8V) were within 0–0.5 V in a pH 3.0 buffer solution with the oxidation peak current correlating well with TTC concentration over a wide range from 0.1 to 160 mg/L. Physical characterizations with Fourier transform infrared (FT-IR), Raman, and X-ray photoelectron spectroscopies (XPS) demonstrated that the oxygen-containing functional groups on GO diminished after the electrochemical reduction at –0.8 V, yet still existed in large amounts, and the defect density changed as new sp2 domains were formed. These changes demonstrated that this adjustment in the number of oxygen-containing groups might be the main factor affecting the electrocatalytic behavior of ERGO. Additionally, the defect density and sp2 domains also exert a profound influence on this behavior. A possible mechanism for the TTC redox reaction at the GC/ERGO-0.8V electrode is also presented. This work suggests that the electrochemical reduction is an effective method to establish new catalytic activities of GO by setting appropriate parameters.