Search Results (32)

Lithium-titanium-sulfur cathodes have garnered interest due to their distinctive properties and potential applications in lithium-ion batteries. They present various benefits, including lower cost, enhanced safety, and greater energy density compared to the commonly used transition metal oxides. The current trend in lithium-ion batteries is to move to all-solid-state chemistries in order to improve safety and energy density. Several chemistries for solid electrolytes have been studied, tested, and characterized to evaluate the applicability in energy storage system. Among those, sulfur-based Argyrodites have been coupled with cubic rock-salt type Li₂TiS₃ electrodes. In this work, Li₂TiS₃ surfaces were investigated with DFT methods in different conditions, covering the possible configurations that can occur during the cathode usage: pristine, delithiated, and overlithiated. Interfaces were built by coupling selected Li₂TiS₃ surfaces with the most stable Argyrodite surface, as derived from a previous study, allowing us to understand the (electro)chemical compatibility between these two sulfur-based materials. Full article

Graphene oxide (GO) was used as an ion-to-electron transducer for all-solid-state nitrate electrodes based on an alkyl ammonium salt as the sensing element. Commercially available carbon screen-printed electrodes modified with GO were used as conductive substrates, whose morphology and distribution along the surface were evaluated by scanning electron microscopy and Raman spectroscopy. The potentiometric performance of the GO-based electrodes revealed a Nernstian slope of −53.5 ± 2.0 mV decade⁻¹ (R² = 0.9976 ± 0.0015) in the range from 3.0 × 10⁻⁶ to 10⁻² M and a lower limit of detection of 1.9 × 10⁻⁶ M. An impressive reproducibility between equally prepared electrodes (n = 15) was demonstrated by a variation of <6% for the calibration parameters. Constant current chronopotentiometry and water layer tests were used to evaluate the potential signal stability, providing similar performance to previously published works with graphene-based ion-selective electrodes. Notably, the GO-based sensors showed the absence of a water layer, a long-term drift of 0.3 mV h⁻¹, and a stable performance (LOD and sensitivity) over 3 months. The applicability of the proposed sensors was demonstrated in determining nitrate levels in water samples with great accuracy, yielding recovery values from 87.8 to 107.9%, and comparable (p > 0.05) results to a commercial nitrate probe. These findings demonstrate the use of GO as an alternative ion-to-electron transducer for the fabrication of all-solid-state potentiometric electrodes. Full article

The importance of phosphates has sparked researchers’ considerable interest in the electrochemical detection of phosphates within aqueous solutions in recent years. In this study, we present a novel all-solid-state phosphate ion-selective electrode (ISE) that integrates copper, copper nanoparticles, and copper phosphate. By modifying the copper substrate of the electrode with a copper nanoparticle film and creating a lamellar copper phosphate film through electrochemical treatment, we significantly enhanced the electrode’s electron transfer efficiency. This microstructure with large specific surface area markedly improved the electrode’s responsiveness to the targeted ions by accelerating the achievement of chemical equilibrium on the electrode surface, thereby boosting its sensitivity and stability. The newly developed electrode was capable of detecting phosphate ions in solutions with a pH range from 6 to 11 and performed optimally in neutral solutions at pH 7, following Nernst principle, with a detection limit of 1 × ${10}^{-6}$ M. The electrode exhibited a short response time of less than 10 s with significant reproducibility, stability, longevity—maintaining functionality for more than two months. It also displayed good selectivity as the electrochemical equilibrium was not influenced by up to 1 mM of potential competing species like ${\mathrm{HCO}}_3^{-}$, ${\mathrm{NO}}_3^{-}$, ${\mathrm{Cl}}^{-}$ and ${\mathrm{SO}}_4^{2-}$. We compared the detection results of current phosphate ion sensor and conventional determination methods for phosphate content in natural lake and aquaculture water samples, with a detection discrepancy of about 10% (RSD). Considering all feasible performance characteristics combined with its low cost, simple manufacture and portability, the sensor provides a new possibility for rapid, reliable, and long-term real-time in situ detection of phosphates. Full article

An all-integrated on-chip electrochemical microcell (10 × 11 mm²) is developed using silicon technology. The potentiometric nitrate ion detection is based on the functionalization of the working microelectrode array with a polymer membrane in fluoropolysiloxane (FPSX) containing ionophore tetradodecylammoniumnitrate (TDDAN) and ionic additive potassium tetrakis[3,5-bis(trifuoromethyl)phenyl]borate (KTFPB) to form an all-solid-state ion selective electrode (ISE). The addition of an ion-to-electron transducing layer between the platinum working electrode and the polymer membrane helped to improve the sensor performances, especially the response time, the sensitivity, and the stability. Composites formed with two conductive polymers were compared: Polyethylenedioxythiophène (PEDOT) and Polypyrrole (PPy), doped with Poly(styrene sulfonate) or double-walled carbon nanotubes (DWCNTs). Full article

This study involved the preparation of an all-solid-state ion-selective electrode (ASS-ISE) with copper and a poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate (PEDOT/PSS) conversion layer through electrode deposition. The morphology of the PEDOT/PSS film was characterized, and the performance of the copper ion-selective film was optimized. Additionally, a microfluidic chip for the ASS-ISE with copper was designed and prepared. An integrated microfluidic chip test system with an ASS-ISE was developed using a self-constructed potential detection device. The accuracy of the system was validated through comparison testing with atomic absorption spectrophotometry (AAS). The experimental findings indicate that the relative standard deviation (RSD) of the integrated ASS-ISE with the copper microfluidic chip test system is 4.54%, as compared to the industry standard method. This value complies with the stipulated requirement of an RSD ≤ 5% in DL/T 955-2016. Full article

Recently, there has been rapid development of electrochemical sensors, and there have been numerous reports in the literature that describe new constructions with improved performance parameters. Undoubtedly, this is due to the fact that those sensors are characterized by very good analytical parameters, and at the same time, they are cheap and easy to use, which distinguishes them from other analytical tools. One of the trends observed in their development is the search for new functional materials. This review focuses on potentiometric sensors designed with the use of various metal oxides. Metal oxides, because of their remarkable properties including high electrical capacity and mixed ion-electron conductivity, have found applications as both sensing layers (e.g., of screen-printing pH sensors) or solid-contact layers and paste components in solid-contact and paste-ion-selective electrodes. All the mentioned applications of metal oxides are described in the scope of the paper. This paper presents a survey on the use of metal oxides in the field of the potentiometry method as both single-component layers and as a component of hybrid materials. Metal oxides are allowed to obtain potentiometric sensors of all-solid-state construction characterized by remarkable analytical parameters. These new types of sensors exhibit properties that are competitive with those of the commonly used conventional electrodes. Different construction solutions and various metal oxides were compared in the scope of this review based on their analytical parameters. Full article

Wearable electrochemical sensors have attracted tremendous attention and have been experiencing rapid growth in recent years. Sweat, one of the most suitable biological fluids for non-invasive monitoring, contains various chemical elements relating abundant information about human health conditions. In this work, a new type of non-invasive and highly stretchable potentiometric sweat sensor was developed based on all-solid-state ion-selective electrode (ISE) coupled with poly(dimethylsiloxane; PDMS) and polyurethane (PU). This highly stretchable composite of PDMS-PU allows the sensor to be robust, with the PDMS providing a flexible backbone and the PU enhancing the adhesion between the electrodes and the substrate. In addition, graphene–carbon nanotube (CNT) network 3D nanomaterials were introduced to modify the ion selective membrane (ISM) in order to increase the charge transfer activity of the ISEs, which also could minimize the formation of water layers on the electrode surface, as such nanomaterials are highly hydrophobic. As a result, the sensor demonstrated a wide detection range of NH₄⁺ from 10⁻⁶ M to 10⁻¹ M with high stability and sensitivity—showing a high sensitivity of 59.6 ± 1.5 mV/log [NH₄⁺] and an LOD lower than 10⁻⁶ M. Under a strain of 40%, the sensor still showed a sensitivity of 42.7 ± 3.1 mV/log [NH₄⁺]. The proposed highly stretchable and robust electrochemical sweat sensor provides a new choice for wearable-device-based personal daily healthcare management beyond hospital-centric healthcare monitoring. Full article

A new solid-contact ion-selective electrode (ISE) sensitive to lead (II) ions, obtained by modifying a polymer membrane with a nanocomposite of carbon nanofibers and an ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate, is presented. Electrodes with a different amount of nanocomposite in the membrane (0–9% w/w), in which a platinum wire or a glassy carbon electrode was used as an internal electrode, were tested. Potentiometric and electrochemical impedance spectroscopy measurements were carried out to determine the effect of the ion-sensitive membrane modification on the analytical and electrical parameters of the ion-selective electrode. It was found that the addition of the nanocomposite causes beneficial changes in the properties of the membrane, i.e., a decrease in resistance and an increase in capacitance and hydrophobicity. As a result, the electrodes with the modified membrane were characterized by a lower limit of detection, a wider measuring range and better selectivity compared to the unmodified electrode. Moreover, a significant improvement in the stability and reversibility of the electrode potential was observed, and additionally, they were resistant to changes in the redox potential of the sample. The best parameters were shown by the electrode obtained with the use of a platinum wire as the inner electrode with a membrane containing 6% of the nanocomposite. The electrode exhibited a Nernstian response to lead ions over a wide concentration range, 1.0 × 10⁻⁸–1.0 × 10⁻² mol L⁻¹, with a slope of 31.5 mV/decade and detection limit of 6.0 × 10⁻⁹ mol L⁻¹. In addition, the proposed sensor showed very good long term stability and worked properly 4 months after its preparation without essential changes in the E⁰ or slope values. It was used to analyze a real sample and correct results of lead content determination were obtained. Full article

In this study, a screen-printed electrode (SPE) modified with cobalt oxide nanoparticles (Co₃O₄ NPs) was used to create an all-solid-state ion-selective electrode used as a potentiometric ion sensor for determining nitrate ion (NO₃⁻) concentrations in aquaculture water. The effects of the Co₃O₄ NPs on the characterization parameters of the solid-contact nitrate ion-selective electrodes (SC-NO₃⁻-ISEs) were investigated. The morphology, physical properties and analytical performance of the proposed NO₃⁻-ion selective membrane (ISM)/Co₃O₄ NPs/SPEs were studied by X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), potentiometric measurements, and potentiometric water layer tests. Once all conditions were optimized, it was confirmed that the screen-printed electrochemical sensor had high potential stability, anti-interference performance, good reproducibility, and no water layer formation between the selective membrane and the working electrode. The developed NO₃⁻-ISM/Co₃O₄ NPs/SPE showed a Nernstian slope of −56.78 mV/decade for NO₃⁻ detection with a wide range of 10⁻⁷–10⁻² M and a quick response time of 5.7 s. The sensors were successfully used to measure NO₃⁻ concentrations in aquaculture water. Therefore, the electrodes have potential for use in aquaponic nutrient solution applications with precise detection of NO₃⁻ in a complicated matrix and can easily be used to monitor other ions in aquaculture water. Full article

In this study, the effect of the active material geometry on the tortuosity in the ion transport path of the electrode composite of an all-solid-state lithium battery was systematically analyzed in terms of the different design and process factors of an electrode. A direct current technique (i.e., chronoamperometry) using an electron-blocking cell was used to analyze the tortuosity to minimize the experimental error. In addition, aluminum oxide was selected as a hypothetical active material in a composite electrode to exclude the possible disturbance of the ion transport signal caused by real active materials. The experimental results showed that the shape and composition of the active material had significant influences on the ion transport characteristics. In particular, when a fibrous material was applied with a high active material ratio, the degree of tortuosity was significantly increased, reaching values as high as 45, due to the insufficient filling in the micropores formed by particle aggregation. Moreover, the tortuosity degree decreased below 15 as the pressing pressure increased during electrode manufacturing, and the cause of this decrease differed with the active material’s particle shape. The analysis results confirmed that the change in tortuosity resulting from the electrode design factors of an all-solid-state battery has distinctive features compared to that for a conventional liquid electrolyte-based lithium-ion battery. Full article

Using single-walled carbon nanotubes (SWCNTs) as an ion-to-electron transducer, a novel disposable all-solid-state desvenlafaxine-selective electrode based on a screen-printed carbon paste electrode was created. SWCNTs were put onto the carbon-paste electrode area, which was protected by a poly (vinyl chloride) (PVC) membrane with a desvenlafaxine-imprinted polymer serving as a recognition receptor. Electrochemical impedance spectroscopy and chronopotentiometric techniques were used to examine the electrochemical characteristics of the SWCNTs/PVC coating on the carbon screen-printed electrode. The electrode displayed a 57.2 ± 0.8 mV/decade near-Nernstian slope with a 2.0 × 10⁻⁶ M detection limit. In 10 mM phosphate buffer, pH 6, the ODV-selective electrodes displayed a quick reaction (5 s) and outstanding stability, repeatability, and reproducibility. The usefulness of electrodes was demonstrated in samples of ODV-containing pharmaceutical products and human urine. These electrodes have the potential to be mass produced and employed as disposable sensors for on-site testing, since they are quick, practical, and inexpensive. Full article

This paper reviews the development of all-solid-state ion-selective electrodes (ASSISEs) for agricultural crop detection. Both nutrient ions and heavy metal ions inside and outside the plant have a significant influence on crop growth. This review begins with the detection principle of ASSISEs. The second section introduces the key characteristics of ASSISE and demonstrates its feasibility in crop detection based on previous research. The third section considers the development of ASSISEs in the detection of corps internally and externally (e.g., crop nutrition, heavy metal pollution, soil salinization, N enrichment, and sensor miniaturization, etc.) and discusses the interference of the test environment. The suggestions and conclusions discussed in this paper may provide the foundation for additional research into ion detection for crops. Full article

Real-time measurements of carbonate ion concentrations in the ocean are critical to advancing marine environmental monitoring and research into deep-sea hydrothermal activity. Herein, we report the first example of deep-sea hydrothermal field exploration using a carbonate ion-selective electrode (ISE). The novel carbonate ISE was composed of a Ni wire as substrate, carbon film as transducers and carbonate-selective membrane layers. This paper describes the preparation process of the electrode and characterises its performance via scanning electron microscopy (SEM) and electrochemical analysis. The detection limit of the electrode for CO₃²⁻ is 2.821 × 10⁻⁶ mol/L, the linear response range is 1.0 × 10⁻⁵–1.0 × 10⁻¹ mol/L and the Nernst slope was −30.4 mV/decade. In April 2021, the carbonate ISE was mounted on multi-parameter sensors with pH and Eh (redox) electrodes for the search of hydrothermal activity at the Southwest Indian Ridge. The simultaneous potential anomalies appeared at this carbonate electrode with the pH and Eh electrodes when passing through the hydrothermal field. The study of the hydrothermal field was supported by the in situ camera video and the sulphide samples. Additionally, the carbonate electrode provides enhanced information of water chemistry for the study of the hydrothermal field. Full article

As an essential electrolyte for the human body, the potassium ion (K⁺) plays many physiological roles in living cells, so the rapid and accurate determination of serum K⁺ is of great significance. In this work, we developed a solid-contact ion-selective electrode (SC-ISE) using MoS₂/Fe₃O₄ composites as the ion-to-electron transducer to determine serum K⁺. The potential response measurement of MoS₂/Fe₃O₄/K⁺-ISE shows a Nernst response by a slope of 55.2 ± 0.1 mV/decade and a low detection limit of 6.3 × 10⁻⁶ M. The proposed electrode exhibits outstanding resistance to the interference of O₂, CO₂, light, and water layer formation. Remarkably, it also presents a high performance in potential reproducibility and long-term stability. Full article

Protoporphyrin IX-based all-solid-state choline (Ch) ion-selective electrodes (ISEs) were fabricated and characterized. Poly (3,4-ethylene dioxythiophene) doped with poly (styrene sulfonate) (PEDOT/PSS) functioning as an ion-to-electron transducer was electropolymerized on the gold wire (0.5 mm diameter). The conductive polymer was covered with a Ch selective membrane containing protoporphyrin IX as an ionophore, which exhibited a lower detection limit of 0.49 μM with the potentiometric method. The Ch sensor performed a wide linear range from 1 μM to 1 mM, a fast response time of less than 5 s, and a decent selectivity of common inorganic and organic ions in the human body. Characteristics such as pH and temperature stability, life span, reproducibility and repeatability were also investigated to be satisfied. With the background of artificial cerebrospinal fluid, the recovery rate in 10${}^{-5}$ M of Ch solution was measured by the standard addition method, revealing the potential for biological application. Full article