Solid-contact pH-selective electrode using multi-walled carbon nanotubes
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Multi-walled carbon nanotubes (MWCNT) are shown to be efficient transducers of the ionic-to-electronic current. This enables the development of a new solid-contact pH-selective electrode that is based on the deposition of a 35-µm thick layer of MWCNT between the acrylic ion-selective membrane and the glassy carbon rod used as the electrical conductor. The ion-selective membrane was prepared by incorporating tridodecylamine as the ionophore, potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate as the lipophilic additive in a polymerized methylmethacrylate and an n-butyl acrylate matrix. The potentiometric response shows Nernstian behaviour and a linear dynamic range between 2.89 and 9.90 pH values. The response time for this electrode was less than 10 s throughout the whole working range. The electrode shows a high selectivity towards interfering ions. Electrochemical impedance spectroscopy and chronopotentiometry techniques were used to characterise the electrochemical behaviour and the stability of the carbon-nanotube-based ion-selective electrodes.
KeywordsPotentiometric ion-selective electrodes Solid-state sensors pH Multi-walled carbon nanotubes
This work was supported by the Spanish MICINN, through the project grants NAN2004-09306-C05-05 and CTQ2006-7-67570/BQU. G.A.C. also acknowledges MICINN for the doctoral fellowship AP2006-04171 and D.G acknowledges the economic support provided by the Universitat Rovira i Virgili.
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