Graphene Composites for Electrochemical Sensing of Dopamine

Abstract

In this study, NiVG (nickel/vanadium oxide@graphene), NiG (nickel oxide@graphene), and VG (vanadium oxide@graphene) composites were synthesized and characterized for the electrochemical sensing of dopamine (DA). The composites were synthesized using green one-pot hydrothermal method at a low temperature of 180º C. The XRD pattern of NiVG samples showed presence of orthorhombic Ni3(VO4)2 (NiV21G and NiV11G) and Ni(OH)2 (NiV21G) phases. FESEM images revealed nanostructured Ni3(VO4)2 anchored/dispersed on the graphene sheets. EDS data indicated that an increased amount of Ni enhanced the uptake of V also. Raman spectra provided valuable insights into the chemical functional groups and bonding characteristics of the materials. The NiV21G/GCE electrode displayed a more pronounced oxidation peak, signifying enhanced adsorption and oxidation of DA. The improved electrocatalytic activity of the NiV21G/GCE electrode was primarily due to the increased electroactive sites provided by the nanometer-sized bimetallic oxide interspersed with Ni(OH)2. Square Wave Voltammetry (SWV) was employed for the analysis of DA as a result of its higher current sensitivity in comparison to CV and DPV. The NiV21G/GCE electrode exhibited a LOD of 0.86 μM ranging linearly from 2 to 200 μM.