Solution-cast films of poly(3,4-ethylenedioxythiophene) as ion-to-electron transducers in all-solid-state ion-selective electrodes (original) (raw)
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Journal of Electroanalytical Chemistry, 2009
Negatively charged multi-walled carbon nanotubes (MWCNTs) were used as dopants in the electrochemical synthesis of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT). The resulting electroactive film, PEDOT(CNT), was used as ion-to-electron transducer (solid contact) in potassium ion-selective electrodes (K + -ISEs) based on plasticized PVC membrane containing valinomycin as neutral ionophore. Potentiometric measurements were carried out to study the analytical performance of solid-contact K + -ISEs, the influence of dissolved O 2 and CO 2 on the potential of the electrodes, and the formation of the interfacial aqueous film. The prepared electrodes were also characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronopotentiometry. The experimental results showed that PEDOT(CNT) has the capability to function as solid contact in fabrication of K + -ISEs. These electrodes, based on PEDOT(CNT) as ion-to-electron transducer, showed high sensitivity and selectivity to K + ion which can be related to the plasticized PVC-based ion-selective membrane containing valinomycin. The stability of the electrode potential, however, was found to depend on the conducting substrate used for deposition of the PEDOT(CNT) film. Results from the CV and EIS revealed that the PEDOT(CNT) contact exhibits high redox capacitance that is favorable for a solid contact.
Sensors and Actuators B: Chemical, 2002
The electrochemical stability of poly(3,4-ethylenedioxythiophene) (PEDOT) is studied in view of its use as ion-to-electron transducer (solid contact) in all-solid-state ion-selective electrodes (ISEs). PEDOT is electrochemically deposited on glassy carbon (GC) and the resulting GC/PEDOT electrodes are studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and potentiometry. Valinomycin-based all-solid-state K þ -ISEs are constructed by placing a K þ -selective poly(vinyl chloride) (PVC)-based membrane on the GC/PEDOT electrode (solid contact). The influence of dissolved O 2 and CO 2 on the potential of the GC/PEDOT electrodes and of all-solidstate K þ -ISEs is studied. PEDOT is compared with polypyrrole (PPy) as the solid contact material. A significant difference between the two conducting polymers (CPs) is that PEDOT is less sensitive to O 2 and CO 2 (pH) than PPy. Therefore, PEDOT is a promising new candidate as ion-to-electron transducer (solid contact) in all-solid-state ISEs based on solvent polymeric membranes that are permeable to O 2 and CO 2 . #
Electrochimica Acta, 2008
Sulfonated thiophenes, sodium 2-(3-thienyloxy)ethanesulfonate (C 6 H 7 S 2 O 4 Na) and sodium 6-(3-thienyloxy)hexanesulfonate (C 10 H 15 S 2 O 4 Na), were synthesized and used in the fabrication of ion-selective electrodes (ISEs) sensitive and selective to Ag + . The Ag + -ISEs were prepared by galvanostatic electropolymerization of 3,4-ethylenedioxythiophene (EDOT) on glassy carbon (GC) electrodes, with either C 6 H 7 S 2 O 4 − or C 10 H 15 S 2 O 4 − as the charge compensator (doping ion) for p-doped poly(3,4-ethylenedioxythiophene) (PEDOT). Potentiometric measurements were carried out with these sensors, GC/PEDOT(C 6 H 7 S 2 O 4 − ) and GC/PEDOT(C 10 H 15 S 2 O 4 − ), to study and compare their sensitivity and selectivity to silver ions. PEDOT(C 6 H 7 S 2 O 4 − ) and PEDOT(C 10 H 15 S 2 O 4 − ) films were also studied by using other techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), electrochemical quartz crystal microbalance (EQCM) and Fourier transform infrared spectroscopy (FTIR).
Electroanalysis, 2014
The cyclic voltammetric properties of several substituted calix[4]arenes were examined in acetonitrile and dichloromethane. The compounds that contained one phenolic group in the macrocyclic cavity were able to be electrochemically oxidised at positive potentials. In acetonitrile, cyclic voltammetry experiments indicated that the phenolic compounds were oxidised in a two-electron (one-proton) process over all measured scan rates (up to 50 V s −1), while in dichloromethane, the oxidation process occurred by one-electron at scan rates ≥5 V s −1 , to most likely form the radical cations. In both solvents, longer timescale (minutes to hours) controlled potential coulometry experiments indicated that the oxidation process occurred by two-electrons per molecule, to form reactive diamagnetic cations that could not be reduced back to the starting materials under electrolysis conditions. The ion-sensing properties of the compounds were investigated in polymer membrane ion-selective electrodes and it was found that they responded reversibly in a Nernstian fashion to Groups 1 and 2 metals and had the highest selectivity to the cesium cation.
Electrochimica Acta, 2014
This work addresses the well-known problem of variations in the standard potential (E • ) of solidcontact ion-selective electrodes (SC-ISEs) that have a conducting polymer (CP) as ion-to-electron transducer covered by a polymeric ion-selective membrane. Poly(3,4-ethylene dioxythiophene) doped with poly(sodium 4-styrenesulfonate), i.e. PEDOT(PSS), was electrodeposited on glassy carbon (GC) disk electrodes and used as the solid contact for three different types of PVC-based membranes in order to elucidate the possibility to electrochemically control E • for this type of SC-ISE. The GC/PEDOT(PSS) electrode was thus coated with potassium-selective membranes with and without the lipophilic salt tetradocedylammonium tetrakis(4-clorophenyl)borate (ETH-500) and by a cation-sensitive membrane without ionophore. The results show that the standard potential of the studied types of SC-ISEs can be shifted by applying a potential that deviates from the open-circuit potential of the electrode in the chosen electrolyte solution or by applying current pulses in the nA range.
The Journal of Physical Chemistry B, 2010
The performance of different poly(3,4-ethylenedioxythiophene) (PEDOT) films was compared by electrochemical, spectroelectrochemical, and time-derivative measurements of absorbance versus potential (linear potentialscan voltabsorptometry) for an overall spectroelectrochemical characterization of the electrochromic properties in ionic liquids such as 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMITFSI). The timederivative signals were monitored at different wavelengths, and information obtained therefrom was complementary to that obtained from conventional cyclic voltammetry. PEDOT films prepared via in situ chemical oxidative polymerization appeared to be much more efficient than electropolymerized and PEDOT-poly(styrenesulfonate) (PSS) reference films, in terms of both contrast ratio and coloration efficiency, which was the case even for PEDOT films deposited on less conductive flexible plastic substrates.
A Highly Stable and Flexible Ca2+ Ion-Selective Sensor Based on Treated PEDOT:PSS Transducing Layer
IEEE Sensors Journal, 2021
In this work, a highly stable Ca 2+ ion-selective sensor was successfully developed by depositing a poly(3,4-ethylenedioxythiophene): poly(styrene-sulfonate) (PEDOT:PSS) layer on top of a carbon paste electrode as an ion-electron transducing layer. The PEDOT:PSS was treated by a co-solvent of ethylene glycol (EG) using the bath-sonication technique to enhance electrical and electrochemical characteristics, and finally coated with Ca 2+ ion-selective membrane cocktail. The developed Ca 2+ ion-selective electrode (Ca 2+-ISE) showed excellent electrochemical properties by much-improved charge transfer kinetics with remarkable electric conductivity. The fabricated Ca 2+-ISE exhibited an excellent sensitivity of 37.7 mV/decade (n = 4) in the range from 10 −4 to 10 −1 M with a rapid response (< 20 seconds). Moreover, the EG-treated PEDOT:PSS (PEDOT:PSS-EG) based ISE showed negligible responses for primary interfering ions of human biofluid samples, proving significant potential selectivity. Furthermore, the negligible drift of open circuit potential (2.78 µV/s) proved the stability of the PEDOT:PSS-EG compared to pristine PEDOT:PSS(10.63 µV/s) based ISE. Based on these analyses, it can be expected that the organic solvent treatment on PEDOT:PSS will pave the way for long-term monitoring of other biochemical compounds.
Conducting polymer-based ion-selective electrodes
Analytica Chimica Acta, 1996
Single-piece, conducting polymer-based, potentiometric sensors with enhanced cationic sensitivity were obtained by doping a polypyrrole with metal-complexing, niultivalent anions. Sulphosalycilic acid, Tiron, Eriochrome Black T and Kalces have been used as doping ions. Predominant sensitivity for copper was observed for the first two dopants, whereas for the two remaining ones, induced response for magnesium and calcium was found, respectively. Interestingly, in all sensors studied the metal-binding properties of the specific ligands known from polar solvents were retained. Hence, the specific reagents can be deliberately utilized for the construction of conducting polymer-based ion-selective sensors.
Single-piece all-solid-state ion-selective electrode
Analytical Chemistry, 1995
A novel concept of a single-piece all-solid-state ionselective electrode (SPE) is introduced. A processable conjugated (electronically conducting or semiconducting) polymer (CP) is dissolved in a cocktail containing the components used for a conventional ion-selective poly-(vinyl chloride) matrix membrane. The cocktail, containing the CP, is cast directly on a solid substrate (glassy carbon), resulting in a SPE. The role of the CP is to mediate the chatge transfer between the substrate and the membrane. Two soluble CPs are studied (i) poly(3octylthiophene) in its undoped state and (i) polyanihe doped (protonated) with bis(2-ethylhh) hydrosen phosphate. hperimental results obtained for lithium-selective SPEs and calcium-selective SPEs are discussed. All the SPEs studied show near-Nernstian responses, and no redox interference is observed as long as the concentration of the CP is sdiciently low. The incorporation of a CP, particularly polyaniline, in the membrane is shown to improve the stability of the standard potential of the SPE compared to the corresponding coated-wire electrude (membrane without CP). Impedance measurements provide information about the charge transfer processes of the electrodes.