Hierarchical Nanocomposites Electrospun Carbon NanoFibers/Carbon Nanotubes as a Structural Element of Potentiometric Sensors

Abstract

This work proposes new carbon materials for intermediate layers in solid-contact electrodes sensitive for potassium ions. The group of tested materials includes electrospun carbon nanofibers, electrospun carbon nanofibers with incorporated cobalt nanoparticles and hierarchical nanocomposites composed of carbon nanotubes deposited on nanofibers with different metal nanoparticles (cobalt or nickel) and nanotube density (high or low). Materials were characterized using scanning electron microscopy and contact angle microscopy. Electrical parameters of ready-to-use electrodes were characterized using chronopotentiometry and electrochemical impedance spectroscopy. The best results were obtained for potassium electrodes with carbon nanofibers with nickel-cobalt nanoparticles and high density of nanotubes layer: the highest capacity value (330 µF), the lowest detection limit (10−6.3 M), the widest linear range (10−6–10−1) and the best reproducibility of normal potential (0.9 mV). On the other hand the best potential reversibility, the lowest potential drift (20 μV·h−1) in the long-term test and the best hydrophobicity (contact angle 168°) were obtained for electrode with carbon nanofibers with cobalt nanoparticles and high density of carbon nanotubes. The proposed electrodes can be used successfully in potassium analysis of real samples as shown in the example of tomato juices.

Modification of Carbon Nanomaterials by Association with Poly(3-octylthiophene-2,5-diyl) as a Method of Improving the Solid-Contact Layer in Ion-Selective Electrodes

“…For comparison, the potential drift for the coated disc electrode in the same test was 0.8 mV/h. As previously reported, the potential drift for electrodes with unmodified materials was 0.09 mV/h for eCNF/K + -ISM, 0.17 mV/h for eCNF-Co/K + -ISM and 0.06 mV/h for eCNF/CNT-NiCo/K + -ISM [15].…”

“…In our previous work, the use of electrospun carbon nanofibers and hierarchical nanocomposites as a permanent contact layer was presented [15]. Hierarchical nanocomposites are materials with a strictly designed architecture [16][17][18].…”

Recent advances in nanomaterial-based solid-contact ion-selective electrodes

“…[39][40][41][42] Therefore, CNT-based ISEs exhibit high analytical performance to detect many ions of biological and environmental importance such as K + , Na + , Mg 2+ , NH 4 + , Ca 2+ , SiO 3 2− , Hg 2+ , Cd 2+ , Pb 2+ , NO 3 − , Al 3+ , ClO 4 − , I − , and Cr 3+ . [43][44][45][46][47][48][49][50][51][52][53] Additionally, the CNT-based SC-ISEs were used extensively for the detection of chemical and pharmaceutical compounds such as bisphenol S, 54 fluoxetine, 55 barbital, 56 nalbuphine. 57 Rius et al 58 pioneered the application of CNTs in SC-ISEs by using single-walled carbon nanotubes (SWCNTs) as an ionto-electron transducer, which exhibited good signal stability (25 days) and a short response time (fewer than 10 s for activi-ties over 10 −5.5 M) for the detection of K + .…”

“…39–42 Therefore, CNT-based ISEs exhibit high analytical performance to detect many ions of biological and environmental importance such as K + , Na + , Mg 2+ , NH 4 + , Ca 2+ , SiO 3 2− , Hg 2+ , Cd 2+ , Pb 2+ , NO 3 − , Al 3+ , ClO 4 − , I − , and Cr 3+ . 43–53 Additionally, the CNT-based SC-ISEs were used extensively for the detection of chemical and pharmaceutical compounds such as bisphenol S, 54 fluoxetine, 55 barbital, 56 nalbuphine. 57…”

Ion-Selective Electrodes with Solid Contact Based on Composite Materials: A Review

“…Comparative studies of materials that can be used as SCs in SCISEs have been described also in [173]. The study involved, among others, electrospun carbon nanofibers with/without incorporated cobalt nanoparticles and hierarchical nanocomposites of carbon nanotubes deposited on nanofibers with different cobalt/nickel nanoparticles.…”