Electrocatalytic performance of a nickel(II) phthalocyanine-carbon nanotube composite towards the detection of Hg2+ ions

Abstract

A composite film of Ni(II) phthalocyanine bearing four benzothiazole (bs) substituents (2) and carboxylic-functionalised multi-walled carbon nanotubes (2-f-MWCNTs) was drop cast on an Au electrode and heated at 50 °C to form a new Au|2-f-MWCNTs sensor for detection of Hg(II) ions. The redox potentials of 2 were measured by cyclic voltammetry, and the processes were affirmed spectroelectrochemically. The nanocomposite of the 2-f-MWCNTs was characterised by Fourier transform Infrared and Raman spectroscopies, and Scanning electron Microscopy. Its electrocatalysis towards Hg(II) was probed by various voltammetric techniques showing higher Faradaic currents in standard redox solutions than the bare or SAMs of 2. Anodic stripping voltammgrams of Hg2+ ions at the Au|2-f-MWCNTs showed good electrocatalytic activity with a linear range spanning 14.4 μM and 1000 μM, and a precision of ± 4.2%. Electrode selectively detected Hg2+ ions in the presence of Pb2+ and Zn2+ ions, while its SWV scan for a mixture of Hg2+ and Cd2+ showed high background noise. Graphic abstract