Voltammetric sensing of dopamine based on a nanoneedle array consisting of NiCo2S4 hollow core-shells on a nickel foam.

Abstract

An array consisting of homogeneous NiCo2S4 hollow core-shell nanoneedles was fabricated and is shown to enable sensitive electrochemical determination of dopamine (DA). The array was grown directly on a nickel foam (NF) substrate by a two-step hydrothermal process. The hierarchical nanoarray consists of a homogeneous NiCo2S4 nanoneedle core and a NiCo2S4 nanosheet shell. A 3-dimensional micro/nano structure is formed due to the presence of the micropores ofthe NF. The electrode was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Compared to a plain NF electrode, the NiCo2S4-modified NF electrode displays higher electrocatalytic activity for the oxidation of DA by differential pulse voltammetry (DPV). The sensor, best operated at a typical working voltage of 134mV (vs. saturated calomel electrode), has a linear response in the 0.5-100μM DA concentration range and a 0.2μM detection limit (at S/N = 3). The electrode is selective over ascorbic acid and uric acid. Graphical abstract Schematic presentation of an electrochemical sensor for selective determination of dopamine based on the use of ahomogeneous NiCo2S4 hollow core-shell nanoneedle array on nickel foam.