Ligand-modified Multi-walled Carbon Nanotubes for Potentiometric Detection of Silver

Abstract

Three novel hybrid materials have been synthesized by ligands: N-(2-vinylsulfanyl-ethylidene)-benzene-1,2-dimine (SBD), N-pyridin-2-ylmethylene-benzene-1,2-dimine (NBD) and N-furan-2-ylmethylene-benzene-1,2-dimine (OBD), covalently linking to multi-walled carbon nanotubes (MWCNTs). These MWCNT hybrid materials were used both as ionophores and as ion-to-electron transducers to construct Ag⁺ carbon paste electrodes. The resulting electrodes show higher selectivity to Ag⁺ than other cations tested. Among the three electrodes, the electrode based on SBD-g-MWCNTs with optimum composition shows the best performance to Ag⁺. It exhibits an excellent Nernstian response to Ag⁺ in the concentration range from 8.8 × 10⁻⁸ to 1.0 × 10⁻¹ M with a detection limit of 6.3 × 10⁻⁸ M, and it can also be used over a wide pH range of 3.0 – 8.0 with a quick response time of 5 s. The response mechanism of the proposed electrode was also investigated by using AC impedance and UV-vis spectroscopy techniques.