Solid Contact Material Research Articles

Recent advancements in solid-liquid triboelectric nanogenerators for energy harvesting and self-powered applications.

The abundance of water on earth provides a large window to utilize the mechanical energy within river currents and ocean waves. In this regard, hydropower harvesting through solid-liquid contact electrification has received considerable interest in the recent past. Despite advancements in nanotechnology, liquid energy harvesting devices, especially solid-liquid triboelectric nanogenerators (S-L TENGs), require efficient engineering of the interfacial properties of their substrates to transfer liquid mass and momentum rapidly with the effective generation/transfer of surface charges. To face this challenge, several parameters such as the selection of material, surface morphology and surface properties are currently being studied to develop a better system architecture for energy harvesting and self-powered application platforms with three different interacting modes of liquid contact. Moreover, several parameters of the contact solvents such as the ionic activity and polarity have been studied to understand the practical applicability of S-L TENGs to harvest energy from different natural and artificial resources. In addition, the scope of harvesting mechanical energy from other volatile organic compounds has been studied recently. Self-powered applications of S-L TENGs in various fields have also been demonstrated by different research groups. This work reviews recent progress in the development of S-L TENGs for the first time in terms of the different properties of solid and liquid contact materials along with their respective applications. Furthermore, the work concludes with perspectives, future opportunities, and major challenges of fabricating S-L TENGs as an efficient energy harvester.

Real-time monitoring of the dissolution of silver nanoparticles by using a solid-contact Ag+-selective electrode

The dissolution kinetics of silver nanoparticles (Ag NPs) to Ag+ ions is a critical factor determining the toxicity of silver nanoparticles. In this work, a solid-contact Ag+-selective electrode (Ag+-ISE) is fabricated and used to monitor the dissolution of Ag NPs. Ordered mesoporous carbon is compared with disordered mesoporous carbon as the solid-contact material for the Ag+-ISE. The ordered mesoporous carbon based solid-contact Ag+-ISE shows a linear potential response in the range of 1.0 × 10−6-1.0 × 10−3 M AgNO3 with the slope of 55.6 ± 0.8 mV/dec (n = 7) and the detection limit of 10−6.8 M. The solid-contact Ag+-ISE is used to monitor the concentration changes of Ag+ during spontaneous dissolution of Ag NPs in deionized water, and the dissolution kinetics of Ag NPs is consistent with that obtained by inductively coupled plasma-mass spectrometry (ICP-MS). Stimulated dissolution of Ag NPs induced by addition of H2O2 to the Ag NP solution is also investigated by the proposed solid-contact Ag+-ISE. This work provides a fast tool for charactering the dissolution of Ag NPs to Ag+ in real time, which is important for studying the toxicology of nanoparticles.

Voltammetric Properties of All‐solid State Ion‐selective Electrodes with Multiwalled Carbon Nanotubes‐poly(3‐octylthiophene‐2,5‐diyl) Nanocomposite Transducer

AbstractVoltammetric response of an all‐solid‐state ion‐selective electrode was studied on example of potassium‐selective sensor with poly(vinyl chloride) based membrane and nanocomposite transducer containing poly(3‐octylthiophene‐2,5‐diyl) and multiwalled carbon nanotubes. Factors limiting the rate of the electrochemical process and the response were discussed. The challenge in voltammetric applications of ion‐selective electrodes is thickness of the plastic membrane. It was found that although a relatively thick ion‐selective membrane was applied, as typically used in potentiometric studies, the position of the reduction peak, corresponding to potassium ions incorporation, was dependent on ions concentration in a Nernstian manner. This opens possibility of deviation from the paradigm of ultrathin membranes in voltammetric applications, thus potentially extending the sensors lifetime. The high resistance of the membrane did not affect the voltammetric characteristics, because the resistance was independent of ions concentration in solution. On the other hand, high resistance results in charge trapping effect in the solid contact material, leading to advantageous retention of the oxidized‐conducting state of the solid contact, independently of the applied electrode potential.

Non-Equilibrium Potential Responses towards Neutral Orcinol Using All-Solid-State Potentiometric Sensors Integrated with Molecularly Imprinted Polymers.

Molecularly imprinted polymer (MIP) receptors have been synthesized, characterized, and applied as new selective receptors in solid-contact ion selective electrodes (ISEs) towards non-dissociated 3,5-dihydroxytoluene (orcinol). Two monomers, namely methacrylic acid (MAA) and acrylamide (AA), were used in the preparation of MIP receptors. Graphene (Gr) was used as the solid contact material between the sensing membrane and the electrical contact substrate. Based on non-equilibrium sensing mechanism, the proposed sensors reveal observably enhanced detection sensitivity towards orcinol with detection limits 1.7 × 10−5 and 3.3 × 10−6 M for sensors based on MIP/MAA and MIP/AA, respectively. The selectivity coefficients measured by the modified separate solution method (MSSM) for the proposed sensors showed good selectivity towards orcinol over most common other phenols and inorganic anions. All measurements were made in the presence of 30 mM phosphate buffer solution (PBS) with a pH of 7.0. Potential stability for the proposed sensors was tested by constant-current chronopotentiometry. No water films were formed between the sensing membrane and the electron conductor substrate. The applicability of MIP/MAA incorporated ISE has been checked by recovery test of orcinol in the presence of soil matrix and by standard addition method.

Single-Walled Carbon Nanotubes (SWCNTs) as Solid-Contact in All-Solid-State Perchlorate ISEs: Applications to Fireworks and Propellants Analysis

Herein, we present reliable, robust, stable, and cost-effective solid-contact ion-selective electrodes (ISEs) for perchlorate determination. Single-walled carbon nanotubes (SWCNTs) were used as solid-contact material and indium (III) 5, 10, 15, 20-(tetraphenyl) porphyrin chloride (InIII-porph) as an ion carrier. The sensor exhibited an improved sensitivity towards ClO4− ions with anionic slope of −56.0 ± 1.1 (R2 = 0.9998) mV/decade over a linear range 1.07 × 10−6 – 1.0 × 10−2 M and detection limit of 1.8 × 10−7 M. The short-term potential stability and the double-layer capacitance were measured by chronopotentiometric and electrochemical impedance spectroscopy (EIS) measurements, respectively. The sensor is used for ClO4− determination in fireworks and propellant powders. The results fairly agree with data obtained by ion chromatography.

Novel Carbon/PEDOT/PSS-Based Screen-Printed Biosensors for Acetylcholine Neurotransmitter and Acetylcholinesterase Detection in Human Serum.

New reliable and robust potentiometric ion-selective electrodes were fabricated using poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) as the solid contact between the sensing membrane and electrical substrate for an acetylcholine (ACh) bioassay. A film of PEDOT/PSS was deposited on a solid carbon screen-printed platform made from ceramic substrate. The selective materials used in the ion-selective electrode (ISE) sensor membrane were acetylcholinium tetraphenylborate (ACh/TPB/PEDOT/PSS-ISE) (sensor I) and triacetyl-β-cyclodextrin (β-CD/PEDOT/PSS-ISE) (sensor II). The sensors revealed clear enhanced Nernstian response with a cationic slope 56.4 ± 0.6 and 55.3 ± 1.1 mV/decade toward (ACh+) ions over the dynamic linear range 1.0 × 10−6–1 × 10−3 and 2.0 × 10−6–1.0 × 10−3 M at pH 5 with limits of detection 2.0 × 10−7 and 3.2 × 10−7 M for sensors I and II, respectively. The selectivity behavior of both sensors was also tested and the sensors showed a significant high selectivity toward ACh+ over different common organic and inorganic cations. The stability of the potential response for the solid-contact (SC)/ISEs was evaluated using a chronopotentiometric method and compared with that of electrodes prepared without adding the solid-contact material (PEDOT/PSS). Enhanced accuracy, excellent repeatability, good reproducibility, potential stability, and high selectivity and sensitivity were introduced by these cost-effective sensors. The sensors were also used to measure the activity of acetylcholinesterase (AChE). A linear plot between the initial rate of the hydrolysis of ACh+ substrate and enzyme activity held 5.0 × 10−3–5.2 IU L−1 of AChE enzyme. Application to acetylcholine determination in human serum was done and the results were compared with the standard colorimetric method.

Screen-printed Microsensors Using Polyoctyl-thiophene (POT) Conducting Polymer As Solid Transducer for Ultratrace Determination of Azides.

Two novel all-solid-state potentiometric sensors for the determination of azide ion are prepared and described here for the first time. The sensors are based on the use of iron II-phthalocyanine (Fe-PC) neutral carrier complex and nitron-azide ion-pair complex (Nit-N3−) as active recognition selective receptors, tetradodecylammonium tetrakis(4-chlorophenyl) borate (ETH 500) as lipophilic cationic additives and poly(octylthiophene) (POT) as the solid contact material on carbon screen-printed devices made from a ceramic substrate. The solid-contact material (POT) is placed on a carbon substrate (2 mm diameter) by drop-casting, followed, after drying, by coating with a plasticized PVC membrane containing the recognition sensing complexes. Over the pH range 6-9, the sensors display fast (< 10 s), linear potentiometric response for 1.0 × 10−2–1.0 × 10−7 M azide with low detection limit of 1.0 × 10−7 and 7.7 × 10−8 M (i.e., 6.2–4.8 ng/ml) for Fe-PC/POT/and Nit-N3−/POT based sensors, respectively. The high potential stability and sensitivity of the proposed sensors are confirmed by electrochemical impedance spectroscopy (EIS) and constant-current chronopotentiometry measurement techniques. Strong membrane adhesion and absence of delamination of the membrane, due to possible formation of a water film between the recognition membranes and the electron conductor are also verified. The proposed sensors are successfully applied for azide quantification in synthetic primer mixture samples. Advantages offered by these sensors are the robustness, ease of fabrication, simple operation, stable potential response, high selectivity, good sensitivity and low cost.

Single-Piece Solid Contact Cu2+-Selective Electrodes Based on a Synthesized Macrocyclic Calix[4]arene Derivative as a Neutral Carrier Ionophore.

Herein, a facile route leading to good single-walled carbon nanotubes (SWCNT) dispersion or poly (3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) based single-piece nanocomposite membrane is proposed for trace determination of Cu2+ ions. The single-piece solid contact Cu2+-selective electrodes were prepared after drop casting the membrane mixture on the glassy-carbon substrates. The prepared potentiometric sensors revealed a Nernstian response slope of 27.8 ± 0.3 and 28.1 ± 0.4 mV/decade over the linearity range 1.0 × 10−3 to 2.0 × 10−9 and 1.0 × 10−3 to 1.0 × 10−9 M with detection limits of 5.4 × 10−10 and 5.0 × 10−10 M for sensors based on SWCNTs and PEDOT/PSS, respectively. Excellent long-term potential stability and high hydrophobicity of the nanocomposite membrane are recorded for the prepared sensors due to the inherent high capacitance of SWCNT used as a solid contact material. The sensors exhibited high selectivity for Cu2+ ions at pH 4.5 over other common ions. The sensors were applied for Cu2+ assessment in tap water and different tea samples. The proposed sensors were robust, reliable and considered as appealing sensors for copper (II) detection in different complex matrices.

All Solid-State Poly (Vinyl Chloride) Membrane Potentiometric Sensor Integrated with Nano-Beads Imprinted Polymers for Sensitive and Rapid Detection of Bispyribac Herbicide as Organic Pollutant.

All-solid-state potentiometric sensors were prepared by using polyaniline (PANI) as the solid contact material. A film of PANI (thickness approximately being 0.25 µm) was deposited on a solid substrate (carbon screen printed platform). The PANI layer was subsequently coated with an ion-selective membrane (ISM) containing uniform-sized molecularly imprinted nanoparticles to produce a solid-contact ion-selective electrode (SC/ISE) for bispyribac herbicide (sensor I). In addition, aliquat 336 was also used as an ion exchanger in plasticized PVC membrane (sensor II). The proposed sensors revealed a remarkably improved sensitivity towards bispyribac ions with anionic slopes of −47.8 ± 1.1 (r2 = 0.9995) and −44.4 ± 1.4 (r2 = 0.9997) mV/decade over a linear range 1.0 × 10−2–8.6 × 10−6 M, 1.0 × 10−2–9.0 × 10−6 M and detection limits of 1.33 and 1.81 µg/mL for sensors I and II, respectively.Selectivity of both sensors is significantly high for different common pesticides and inorganic anions. The potential stability of the SC/ISEs was studied using chronopotentiometry. Electrochemical impedance spectrometry was used to understand the charge-transfer mechanisms of the different types of ion-selective electrodes studied. The impedance response of the electrodes was modelled by using equivalent electrical circuits. The sensors were used for a direct measurement of the bispyribac content in commercial herbicide formulations and soil samples collected from agricultural lands planted with rice and sprayed with bispyribac herbicide. The results agree fairly well with data obtained using HPLC method.

Advantages of Amperometric Readout Mode of Ion‐selective Electrodes under Potentiostatic Conditions

AbstractAmperometric responses of all‐solid‐state ion‐selective electrodes, recorded under potentiostatic conditions, were studied on example of potassium‐selective sensors with polypyrrole solid contact, at potential corresponding to reduction of the solid contact material and accompanying transfer of potassium ions across the membrane. Selective and stable in time linear dependences of current vs. logarithm of analyte concentration were recorded, resulting from high membrane resistance and changing membrane potential. The influence of experimental parameters as applied potential or thickness of the membrane was discussed. Advantages of the amperometric mode compared to potentiometric one relate to possibility of tailoring analytical parameters (sensitivity, magnitude of the signal) as well as over one order of magnitude decrease of the detection limit. The latter effect is achieved due to externally forced incorporation of potassium ions from the solution to the membrane, compensating their spontaneous release to the sample solution. A method of experimental setup simplification was proposed, with application of two‐electrode system, which can be used in the absence of external polarization source. The required driving force for the current flow was assured by spontaneous oxidation process occurring at the second electrode, coupled with reduction of the solid contact material of the ion‐selective electrode. In this case also stable in time calibration plots can be recorded.

Rectifying effect for ion-selective electrodes with conducting polymer solid contact

Asymmetric influence of galvanostatic polarization of all-solid-state ion-selective electrodes was studied on example of a potassium-selective sensor with poly(vinyl chloride) based membrane and solid contact: typically polypyrrole doped by chloride ions. For a high thickness of the solid contact layer anodic polarization was characterized by significantly higher overpotential compared to cathodic one, thus, a “rectifying” effect of the membrane was observed. The difference in polarization influence was explained by limited availability of mobile ions on the membrane / solid contact interface. The chronopotentiometric response was discussed in terms of an equivalent circuit containing the solid contact capacitance, the membrane and charge transfer resistances. It was shown that intentional incorporation of mobile ions to the membrane or solid contact by appropriate conditioning or application of cation-exchanging solid contact material resulted in reduction or disappearance of the rectifying effect.The presence of polarization asymmetry is significant not only for application of current based electrochemical methods to ion-selective electrodes but also for newly developing area of application of lipophilic membranes to modify electrical parameters of electrolyte gated field-effect transistors.

Calcium-selective electrodes based on photo-cured polyurethane-acrylate membranes covalently attached to methacrylate functionalized poly(3,4-ethylenedioxythiophene) as solid-contact

We report here the fabrication of solid-contact calcium-selective electrodes (Ca2+-SCISEs) made of a polyurethane acrylate ion-selective membrane (ISM) that was covalently attached to the underlying ion-to-electron transducer (solid-contact). Methacrylate-functionalized poly(3,4-ethylenedioxythiophene) (Meth-PEDOT) and Meth-PEDOT films containing either multiwalled carbon nanotubes (MWCNT) or carboxylated MWCNT (cMWCNT) were used as solid contacts. The solid contacts were deposited by drop-casting on screen-printed electrodes and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and potentiometry. Covalent binding between the solid contact and the ISM was obtained via photopolymerization in order to increase the robustness of the Ca2+-SCISEs. The performance of the Ca2+-SCISEs was studied by measuring their potentiometric response and their sensitivity to light, oxygen and carbon dioxide. Meth-PEDOT was found to be a promising solid-contact material to develop low-cost and easy to prepare ISEs.

Electrosynthesized polypyrrole/zeolite composites as solid contact in potassium ion-selective electrode

Polypyrrole/zeolite composites were studied as solid contact material in potassium ion-selective electrodes (K+-ISEs). Proton-exchanged Zeolite Socony Mobil-5 (H-ZSM-5) with SiO2/Al2O3 ratios of 23, 80 and 280 were electrochemically synthesized with polypyrrole (PPy). The anionic groups on the zeolite framework functioned as the counter ions for PPy during the reaction. H-ZSM-5 particles were observed on the surface as well as inside the composite films. PPy/H-ZSM-5 composites gave a similar cyclic voltammogram as PPy doped with chloride, PPy(Cl−). The hydrophobicity of the composites decreased in the order PPy/H-ZSM-5–23>PPy/H-ZSM-5–80>PPy/H-ZSM-5-280. The redox capacitance of the composite was better utilized than that of PPy(Cl−) after they were coated with a plasticized PVC membrane. PPy/H-ZSM-5 composite-based K+-ISEs exhibited similar potential stability as the PPy(Cl−)-based K+-ISE. However, when compared with the PPy(Cl−)-based K+-ISE, the detection limit of PPy/H-ZSM-5 composite-based K+-ISEs was enhanced after a long-term conditioning.

Ion-selective electrodes with superhydrophobic polymer/carbon nanocomposites as solid contact

Possibility of using superhydrophobic polymer/carbon nanocomposites as a new type of solid-contact material for solid-state ion-selective electrodes has been presented for example potassium-sensitive electrodes. The solid contact layers were prepared with the highly porous graphene/carbon black – fluorinated acrylic copolymer. Potassium-selective electrodes were exhibited a good Nernstian response with a slope of 59.10 mV/dec in the range from 10−6.5 to 10−1 M KCl. The stability of the electrical potential of the new solid-contact electrodes was tested by performing current-reversal chronopotentiometry, and the electrodes capacitance is 1471 μF. Due to the large capacitance and super hydrophobic character of the solid contact the developed electrodes exhibit excellent a long-term potential stability.

3D simulation of eutectic interaction of Pb–Sn system using Moving Particle Semi-implicit (MPS) method

The eutectic reaction phenomenon was analyzed based on the Moving Particle Semi-implicit (MPS) method. The improved MPS code was applied to three-dimensional Pb–Sn system experiments conducted at Central Research Institute of Electric Power Industry (CRIEPI). The experiments dealt with solid–solid contact materials at 225 and 205°C. The mass diffusion process was modeled based on Fick’s second law. The criterion of eutectic reaction was modeled based on binary phase diagram. The calculated penetration rates, i.e. height reduction rates, were compared with the experimental measurements. The results obtained by the MPS simulations exhibit good agreement with the experiments carried out at 205 and 225°C. MPS simulation predicted that Sn particle will liquefy earlier than Pb particle.

Using sp2-C dominant porous carbon sub-micrometer spheres as solid transducers in ion-selective electrodes

Potential stability is one of the most intractable challenges for solid-contact ion-selective electrodes (SC-ISEs) with regard to the classic inner-reference ISEs. Among the well-established electrode structures for SC-ISEs, solid-contact transducer layer is the most crucial component. Herein, we introduce porous carbon sub-micrometer spheres (PC-SMSs) as a promising solid-contact material for fabrication of highly stable K+-SC-ISE. Systematic characterizations including contact angle, electrochemical impedance spectroscopy and cyclic voltammetry demonstrate that the PC-SMSs disclose high hydrophobicity and large interfacial capacitance, which efficiently eliminate the water-layer and stabilize the potential of K+-SC-ISEs. The developed PC-SMSs electrode also exhibits good long-term stability as well as anti-interferences from O2 and CO2.

Influence of hydrophobization of the polyazulene ion-to-electron transducer on the potential stability of calcium-selective solid-contact electrodes

We introduce here electrosynthesized polyazulene (PAz) as a new ion-to-electron transducer material in solid-contact ion-selective electrodes (SC-ISEs). It is shown that the neutral form of PAz possesses high hydrophobicity (water contact angle: 126±14°) due to its aromatic carbon structure. This makes PAz attractive as a solid-contact (SC) material in SC-ISEs in combination with its high redox capacitance which is three times higher than for PEDOT-PSS. We have studied the electrochemical stability of PAz in direct contact with aqueous electrolyte solutions and applied it as the SC layer buried under a calcium-selective plasticized poly(vinyl chloride) ion-selective membrane (ISM). It is demonstrated that the hydrophobization of the PAz solid-contact at E≤0.2V significantly improved the potential stability of the calcium-selective SC-ISEs which showed a potential drift of only 0.5mVh−1 when the ISMs were for the first time contacted with 0.1M CaCl2 for 24h. Simultaneous determination of the potential stability and the water uptake with the FTIR-ATR spectroscopy could not clearly prove the correlation between low water content at the PAz/substrate interface and the good potential stability obtained with the pre-hydrophobized SC-ISEs. This is due to the relatively uneven surface morphology of the PAz film making the evanescent standing wave of the IR beam to sense water not only in the PAz transducer layer, but also in the ISM. Hence, it is not possible to distinguish between the distribution of water in the ISM and the PAz solid-contact layer. The new SC material presented here was also characterized with cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy.

Standard Potential of Ion-Sensors

The potentiometric measurement of ions belongs to the most frequently applied electroanalytical methods. It is owing to the need of routine determinations of the main blood electrolytes (Na+, K+, Cl-, and HCO3 -), pH and PCO2. Growing demand for improved reliability of the sensors response and manageable response time is associated with their fundamental properties characterized by sensitivity, selectivity, detection limit and standard potential [1]. The latter should be preferably stable over certain time, and in this way not to be a source of analytical error.The interpretation of the standard (resp. formal) potential is often ignored owing to the application of internal electrode solution, i.e. symmetric ion-sensor systems. However, the present wave in ion-sensor technology typically utilizes all-solid-state sensor architecture, in which the internal liquid contact is substituted by a solid contact, with resulting assymetricion-sensors. This type of contact was first used for ion-selective electrodes with a solid-state (crystalline) membrane, and made by platinum, silver, carbon. More recently, conducting polymer as a solid-contact material for the ion-selective electrodes with plastic membranes was proposed [2]. Very recently the application of nanostructured materials was offered [3]. Beyond any doubt, the understanding of the reason(s) of standard potential stability of the asymmetric solid-contact ion-sensors is of a primary importance, but rarely undertaken. Thermodynamic interpretation the standard potential of the asymmetric all-solid-state ion-selective sensors will be presented. This interpretation is related to the fundamental concepts metallic electrodes and all-solid-state electrodes presented by Trasatti [4] and Buck & Koebel [5], and extended by Lewenstam [6] for the solid contacts made of conducting polymers. The applicability of the interpretation for the whole family of all-solid-state ion-selective sensors will be discussed.

Evidence for a Surface Confined Ion-to-Electron Transduction Reaction in Solid-Contact Ion-Selective Electrodes Based on Poly(3-octylthiophene)

The ion-to-electron transduction reaction mechanism at the buried interface of the electrosynthesized poly(3-octylthiophene) (POT) solid-contact (SC) ion-selective electrode (ISE) polymeric membrane has been studied using synchrotron radiation-X-ray photoelectron spectroscopy (SR-XPS), near edge X-ray absorption fine structure (NEXAFS), and electrochemical impedance spectroscopy (EIS)/neutron reflectometry (NR). The tetrakis[3,5-bis(triflouromethyl)phenyl]borate (TFPB(-)) membrane dopant in the polymer ISE was transferred from the polymeric membrane to the outer surface layer of the SC on oxidation of POT but did not migrate further into the oxidized POT SC. The TFPB(-) and oxidized POT species could only be detected at the outer surface layer (≤14 Ǻ) of the SC material, even after oxidation of the electropolymerized POT SC for an hour at high anodic potential demonstrating that the ion-to-electron transduction reaction is a surface confined process. Accordingly, this study provides the first direct structural evidence of ion-to-electron transduction in the electropolymerized POT SC ISE by proving TFPB(-) transport from the polymeric ISE membrane to the oxidized POT SC at the buried interface of the SC ISE. It is inferred that the performance of the POT SC ISE is independent of the thickness of the POT SC but is instead contingent on the POT SC surface reactivity and/or electrical capacitance of the POT SC. In particular, the results suggest that the electropolymerized POT conducting polymer may spontaneously form a mixed surface/bulk oxidation state, which may explain the unusually high potential stability of the resulting ISE. It is anticipated that this new understanding of ion-to-electron transduction with electropolymerized POT SC ISEs will enable the development of new and improved devices with enhanced analytical performance attributes.

Durable PEDOT:PSS films obtained from modified water-based inks for electrochemical sensors

Printing of conducting polymer films from water-based inks is a powerful method that can facilitate the fabrication of various types of electrochemical sensors. This paper reports on the use of ethylene glycol and quaternary ammonium salts as additives to water-based poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) inks in order to obtain conducting polymer films with improved adhesion to a carbon-based electrode substrate in aqueous environment. The modified PEDOT:PSS films deposited on glassy carbon were studied in aqueous solutions by cyclic voltammetry, electrochemical impedance spectroscopy, and potentiometry. It was found that PEDOT:PSS films modified with ethylene glycol and quaternary ammonium salts exhibit excellent adhesion to glassy carbon even after immersion in aqueous solutions for more than two months. The modified PEDOT:PSS films were electroactive, showed relatively fast ion transport properties, and were successfully applied as solid-contact material in lead(II)-selective electrodes.