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

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.