Structural and electrochemical characterization of carbon ion beam irradiated reduced graphene oxide and its application in voltammetric determination of norepinephrine

Abstract

Irradiation of reduced graphene oxide (rGO) sheets using a 50 MeV C⁴⁺ ion beam has been implemented to create defects. The changes in the charge transfer resistance (R_CT) and structural variations in rGO upon irradiation have been studied using electrochemical impedance spectroscopy (EIS), Raman spectroscopy and field emission scanning electron microscopy (FE-SEM). Irradiation of rGO with the 50 MeV C⁴⁺ ion beam resulted in three fold decreased charge transfer resistance (R_CT 32.91 Ω) in comparison to 93.42 Ω corresponding to pristine rGO. Electrochemical properties of irradiated rGO have been further investigated by developing an irradiated rGO modified glassy carbon electrode (GCE) for the analysis of norepinephrine (NE). Voltammetric experiments showed that irradiated rGO modified GCE (irradiated rGO/GCE) exhibited superior response towards NE oxidation in comparison to both the pristine rGO/GCE and bare GCE. Thus, NE has been quantified using irradiated rGO/GCE in a linear concentration range of 1–200 μM with a detection limit of 50 nM. Detection sensitivities corresponding to bare, pristine rGO and irradiated rGO modified GCE were 0.0173, 0.1335 and 0.769 μA μM⁻¹, respectively, demonstrating substantial improvement in sensing and electrocatalytic behaviour of rGO on exposure to the ion beam. To ensure the analytical applicability of the fabricated sensor it has been successfully applied for the estimation of norepinephrine (NE) in injections, human urine and serum samples and achieved a recovery >93% with an R.S.D. < 3.5%.