Cu2+-1,10-phenanthroline-5,6-dione@electrochemically reduced graphene oxide modified electrode for the electrocatalytic determination of L-cysteine

Abstract

The Cu2+-1,10-phenanthroline-5,6-dione@electrochemically reduced graphene oxide (Cu2+-phen-dione@ERGO) composite electrodes were prepared by the electrochemical immobilization of 1,10-phenanthroline on the ERGO modified glassy carbon electrode (ERGO/GC) for the electrocatalytic determination of L-cysteine (CySH). The as-fabricated Cu2+-phen-dione@ERGO/GC electrode was characterized by field emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. The electrocatalytic redox behavior of CySH on the Cu2+-phen-dione@ERGO/GC electrode was investigated in phosphate buffer solution by cyclic voltammetry (CV) and amperometry studies. The results indicate that the Cu2+-phen-dione@ERGO/GC modified electrodes exhibit enhanced electrocatalytic peak currents. The double electrocatalytic redox probe at the same operating potential demonstrated excellent electrocatalytic activity towards CySH. The Cu2+-phen-dione@ERGO/GC electrode demonstrated wide concentration range detection from 10.0 to 32,344.0 μM (sensitivity of 0.0009 μA μM−1) and low detection limit (S/N = 3) of 2.0 μM. The as-fabricated CySH sensor electrode has good interference tolerance ability with ascorbic acid, uric acid, sodium nitride, homocysteine, fructose, glucose, glutathione, and alanine. Also, the proposed electrode has been successfully applied to the real-time determination of CySH in human urine sample without any sample pretreatment with the analytical recoveries ranging from 97.8% to 99.5%.