Carbon Nanomaterials - Poly(3-octylthiophene-2,5-diyl) – Hydrous Iridium Dioxide Triple Composite Materials as Superhydrophobic Layers for Ion-Selective Electrodes

Abstract

In this paper, we introduce the new triple composite material consisting of three significantly different materials: carbon nanomaterial (carbon nanotubes and carbon black), conducting polymer (poly(3-octylthiophene-2, 5-diyl) and metal oxide (hydrous iridium dioxide). Combining those three components enabled to obtain superhydrophobic materials (of contact angle value up to 180°). Both designed materials were characterized with high values of electrical capacitance parameters (1.5 and 0.9 mF) and low values of resistance (72.9 ± 0.3 kΩ and 23.5 ± 0.2 kΩ for NT-based and CB-based electrode, respectively). The new functional material was implemented into potassium-selective electrodes in order to improve their electrical and analytical parameters. This is the first presented so far potentiometric sensor with solid-contact layer composed of three significantly different materials. The superhydrophobic layer of triple composite material improved (in contrast to previous solutions) long-term stability (characterized by potential drift of 43 μV h−1 and 79 μV h−1 for the NT-based and CB-based electrode, respectively) and repeatability enabled limiting the number of necessary calibrations. Potentiometric sensors presented in the scope of this work enable potassium determination in the wide range of potassium ions (from 10−6 to 10−1 M of K+ ions). The possibility of practical application was successfully confirmed by the analysis of potassium in vegetable juices.