Search Results (648)

The rapid detection of organophosphorus (OP) compounds is crucial for safeguarding human health and ensuring food safety. This study presents a novel wearable electrochemical biosensor that integrates miniaturized screen-printed electrodes with wearable devices to achieve real-time, on-site OP detection. The biosensor was fabricated by constructing a screen-printed carbon electrode (SPCE) on a thermoplastic polyurethane (TPU) substrate, sequentially modified with graphene (GR), gold nanoparticles (AuNPs), and organophosphorus hydrolase (OPH), and finally encapsulated with Nafion. This SPCE/GR/AuNPs/OPH/Nafion configuration yields a highly flexible and portable device. The detection principle relies on the enzymatic hydrolysis of methyl paraoxon (MPOX) by OPH, generating p-nitrophenol (PNP), which is quantitatively measured via square wave voltammetry (SWV). The sensor exhibits a broad linear detection range (30–400 μM) with a strong linear correlation (R² = 0.995) and a low detection limit (0.321 μM). It demonstrates excellent selectivity against common interfering substances, including urea, sucrose, and various metal ions. Application to real-world samples such as cabbage and tap water yielded high recoveries (107.2% for cabbage and 101.2% for tap water), with relative standard deviations (RSDs) below 8%. Furthermore, the biosensor maintains robust flexibility and mechanical resilience, with less than 5% signal loss after 100 bending cycles, confirming its suitability for wearable applications and reliable operation under mechanical stress. This innovative, flexible electrochemical biosensor provides a powerful and reliable platform for rapid OP detection, particularly in complex testing environments. Full article

This review summarizes the current state of research on perfluorinated sulfonic acid (PFSA) ionomers, including both classic Nafion and a wide range of alternative chemical modifications, as well as new-generation composite and stabilized membranes. The accumulation of a large body of experimental and modeling data in recent years highlights the need to rethink the differences between traditional ionomers and their modern counterparts, which is especially relevant in light of the development of new materials and their expanding applications. PFSA ionomers have a rich research history, playing a key role in the development of polymer-electrolyte fuel cell technologies and other electrochemical systems. At the same time, these materials have become a unique interdisciplinary platform, stimulating the development of new methods of characterization, modeling, and analysis. In PFSA research, technological progress is closely intertwined with fundamental science, encompassing electrochemistry, polymer physics, mechanics, chemistry, and multiscale modeling. The data we collected allowed us to identify new structural and functional patterns, analyze the behavior of ionomers in various states—from thin films and interfaces to bulk membranes—and summarize numerous previously fragmented relationships. Full article

Ionic polymer–metal composites consist of an ion-conducting polymer–gel membrane sandwiched between two flexible electrodes, representing a class of soft electroactive materials capable of large deformation under low voltage. The gel membrane, swollen with solvent, facilitates ion migration under an electric field, enabling actuation. Tailoring the interfacial architecture between the electrode and the polymer–gel membrane is pivotal for advancing high-performance IPMC actuators. This study presents a comparative investigation of three core–shell nanocomposite electrodes, fabricated via in situ polymerization, for IPMC applications. Among these, the polyaniline-coated multi-walled carbon nanotube composite exhibits a deliberately designed hierarchical structure, with a specific surface area of 32.345 m²·g⁻¹ and a conductive doped polyaniline shell, as confirmed through XPS analysis. This optimized interface enables superior charge storage and transport, endowing the corresponding electrode with a specific capacitance of 40.28 mF·cm⁻² at 100 mV·s⁻¹—3.2 times greater than that of conventional silver-based electrodes—along with a reduced sheet resistance. When integrated with a Nafion ion–gel membrane, the PANI@MWCNT electrode achieves a 67% increase in force density and a larger displacement output compared to standard devices, directly correlated with its enhanced electrical and electrochemical properties. This work highlights the critical role of core–shell interfacial engineering in governing electromechanical performance at the electrode–gel interface and offers a practical design strategy for developing high-performance, cost-effective IPMC actuators for soft robotics, flexible electronics, and related applications. Full article

In the present study, an amperometric aflatoxin B1 sensor was constructed via modifying a nano-graphite carbon paste microelectrode with a cationic surfactant of cetyltrimethylammonium bromide (CTAB) and a perfluorosulfonic acid resin of Nafion through a simple and controllable electrochemical scanning method. The experiment results show that CTAB–Nafion composite film has a good catalytic effect on the electrochemical response of aflatoxin B1. The electrocatalytic mechanism was investigated with the aid of different analytical techniques, including square wave voltammetry, electrochemical impedance spectroscopy, chronocoulometry, energy-dispersive spectroscopy and scanning electron microscopy. Under the optimal conditions, the linear range of the sensor is from 0.1 nM to 100 nM, and its detection limit and sensitivity are 20 pM (S/N = 3) and (24.9 ± 1.51) μA/nM, respectively. The accurate and rapid detection of aflatoxin B1, which has strong carcinogenicity, is of great significance for food quality monitoring and the protection of human health. Therefore, finally, the sensor was used to detect the concentration of aflatoxin B1 in milk and soy sauce samples, and the favorable recovery results indicated its good application prospects. Full article

A novel sensitive and selective electrochemiluminescence (ECL) sensor using nitrogen-doped graphyne as the platform was proposed for kanamycin (KAN) detection. First, nitrogen-doped graphyne nanomaterial (1N-GY) with high conductivity was synthesized using a high-energy ball milling method. Compared with ordinary graphyne, the addition of nitrogen atoms can improve the conductivity of the material and reduce the electronic migration energy barrier. Then it was used as a substrate material of the ECL sensor, not only increasing the conductivity of the biosensor but also improving the sensitivity of the ECL sensor by providing more immobilization space for the luminescent probe of Nafion-coated mesoporous silica adsorbed Ru(bpy)₃²⁺ (mSiO₂@Nafion@Ru(bpy)₃²⁺). On this basis, mSiO₂@Nafion@Ru(bpy)₃²⁺ functionalized DNA probes were used as luminescent and capture probes to specifically recognize different concentrations of KAN to produce ECL signals. Under optimal conditions, the proposed ECL sensor exhibited good linearity (10⁻¹²–10⁻⁶ M KAN) and a low detection limit of 1.08 pM. The prepared biosensor with good stability and selectivity successfully detected KAN in honey and milk samples, with spiked recovery rates ranging from 98% to 111.79%. This method not only expands the application of 1N-GY as a novel graphitic material in ECL biosensors but also provides an effective way to check antibiotics in dairy products. Full article

The rapid increase in end-of-life lithium-ion batteries demands sustainable recycling routes for lithium recovery. This work presents a novel integrated hydrometallurgical–electrodialysis process designed specifically for recovering lithium from off-specification NMC cathode materials while enabling full reagent recyclability. Selective leaching with oxalic acid was optimised by setting the water-to-oxalic acid dihydrate ratio (H₂O/OA·2H₂O) to 7.3:1 w/w, achieving 81% lithium extraction at room temperature within 2 h while limiting the co-dissolution of Ni, Co and Mn to 0.2%, 1.6% and 1.7% by weight, respectively. The resulting leachate was processed in a four-chamber electrodialysis cell equipped with two Nafion 117 cation-exchange membranes and one Neosepta AMX-fmg anion-exchange membrane operating at −1.6 V versus Ag/AgCl, enabling 96% lithium recovery and 98% oxalic acid recovery. The regenerated oxalic acid stream (41.8 g L⁻¹) was fully restored to its initial concentration and reused in successive cycles without performance loss. Subsequent precipitation of lithium with Na₂CO₃ yielded 99.3%-pure Li₂CO₃. This combined leaching–electrodialysis–precipitation presents a high selectivity, low-waste, circular recovery system, offering a scientifically original approach that integrates reagent regeneration with high-purity lithium production. Full article

Herein, (Nafion-treated) (30 wt%) NiO_x/graphene (GP) were prepared at 250 °C and 450 °C and investigated as materials for dopamine electrochemical detection. Initially, characterization of the samples was performed using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. Subsequently, they underwent electrochemical evaluation using cyclic voltammetry, linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), and chronoamperometry (CA) techniques. All electrochemical measurements of the dopamine oxidation reaction (DOR) were performed in a 0.1 M phosphate buffer solution (PBS) at pH of 7.00 and at temperature of 36.6 °C. It was found that Nafion addition to the electrocatalysts surface facilitates access of the cationic dopamine molecule to their active centers being attributed to Nafion cation permeability. Nafion-NiO₂₅₀/GP exhibited higher activity towards the DOR reaction. The limit of detection (LOD) for the lower linear range of 0.5–10 μM was calculated to be 0.8 μM, with a sensitivity of 3.086 μA μM⁻¹cm⁻². Furthermore, the Nafion NiO₂₅₀/GP/GC electrode exhibited high selectivity towards DA, as well as good repeatability and reproducibility with an acceptable level of deviation, and excellent storage stability. The six electrodes produced from the Nafion-NiO₂₅₀/GP showed 8.28% reproducibility (RSD), indicating adequate behavior, while the same electrode after six measurements over a 30-day period showed an RSD of 5.50%, indicating a reliable electrode. Full article

This study reports a sustainable and experimentally simple electrochemical platform for monitoring trace Pb²⁺ using pumpkin peel-derived carbon black (CB) as a modifier on a Nafion-coated glassy carbon electrode (CB/Nafion-GCE). Agricultural waste pumpkin peels were converted into CB, offering a low-cost and environmentally friendly sensing material. CB produced at 650 °C was systematically characterized by SEM, TEM, EDX, XRD, FT-IR, and BET, revealing a mesoporous structure, high surface area, and partial graphitization that enlarged the electroactive area and reduced charge transfer resistance relative to the bare GCE. Under optimized square wave anodic stripping voltammetry (SWASV) conditions, the glassy carbon electrode modified with CB produced at 650 °C (CB650-GCE) exhibited a well-defined linear response towards Pb²⁺ with a limit of detection of approximately 0.19 µM and a limit of quantification of about 0.58 µM, together with good selectivity against common coexisting metal ions. The sensor also achieved satisfactory recoveries in tap and seawater samples, demonstrating its potential as a practical, green analytical tool for routine lead surveillance in environmental waters. Full article

Modified electrodes were obtained by immobilizing Mn³⁺ complexes with the following tetraazamacrocycles (1,4,7,10-tetraazacyclododecane ([12]aneN₄), 1,4,8,11-tetrazacyclotetradecane ([14]aneN₄), 1,4,7,11-tetrazacyclotetradecane (iso[14]aneN₄), and 1,4,8,12-tetrazacyclopentadecane ([15]aneN₄) in a Nafion film on the surface of a glassy carbon electrode (GCE). Based on spectroelectrochemical, chronopotentiometric, and chronoamperometric studies, oxidation of mononuclear complexes to dinuclear di-μ-oxo complexes of Mn³⁺ and Mn⁴⁺ was observed, and the mechanism and influence of Nafion on this process were determined. On the basis of voltammetric and chronocoulometric studies, the electroactivity, stability, and diffusion rates of such modified electrodes were demonstrated. Based on voltammetric and chronocoulometric studies, their electrocatalytic properties were analyzed in relation to the oxidation of model compounds used in this type of research, namely, ascorbic acid, glycolaldehyde, and glycolic acid. Full article

Perfluorinated sulfonic acid ionomer (PFSAI) dispersions are widely used for fabrication of ion-conducting membranes and catalyst layers for hydrogen fuel cells. The conformation and concentration of PFSAIs affect the properties of the final product and depend on the liquid phase in dispersion. Here we present a novel method of preparing water/alcohol dispersions based on Nafion and Aquivion PFSAI by using a high-pressure homogenizer. The proposed route is faster and much safer and allows achieving higher PFSAI concentrations in comparison with the autoclave technique used for commercial dispersion preparation. The comparison of dispersion viscosity and PFSAI aggregate size was performed for both techniques and demonstrated similar values. Analysis of the morphology of membranes obtained from different dispersions by the casting method revealed differences in structure, which disappeared after annealing. These results highlight an important novel method of preparing PFSAI dispersions and the use of membrane morphology analysis for membrane quality evaluation. Full article

The commercialization of proton-exchange-membrane fuel cells is constrained by the limitations of perfluorosulfonic acid membranes like Nafion, which suffer from high methanol crossover, humidity-dependent conductivity, high cost, and poor environmental sustainability. This review presents a comprehensive analysis of aquaporin-inspired chitosan/cellulose (AQP-CS) composite membranes as a transformative, bio-inspired alternative. The central design paradigm integrates a sustainable chitosan/cellulose matrix—which offers inherent mechanical stability, tunable proton conduction, and excellent fuel barrier properties—with biomimetic water channels engineered for selective hydration transport. This synergistic architecture aims to fundamentally decouple water management from proton conduction, directly addressing the core performance flaw of conventional membranes. The review is structured to explicitly trace the logical pathway from the foundational material properties of chitosan and cellulose to the functional requirements for integrating synthetic aquaporin-mimetic components. Experimental evidence from advanced chitosan composites, demonstrating proton conductivities up to 0.131 S cm⁻¹ alongside drastically reduced methanol permeability, validates the potential of this approach. Consequently, AQP-CS composites establish a novel framework for developing next-generation fuel cell membranes that combine high performance with ecological design. However, key challenges in the stable integration of biomimetic channels, long-term operational durability, and scalable manufacturing must be resolved to enable practical deployment and mark a significant leap toward sustainable energy conversion technologies. Full article

Heterogeneous ion-exchange membranes (IEMs) are cost-effective but suffer from low electrochemical efficiency due to surface inhomogeneities. While surface coating with homogeneous ionomers is a known modification strategy, its direct impact on electro-hydrodynamic behavior and desalination performance has rarely been visually verified. In this study, we employed a microfluidic platform to visualize and quantify the performance enhancement of Nafion-coated heterogeneous cation exchange membranes (CEMs). Contrary to conventional theories linking electro-convection (EC) to surface hydrophobicity, our results show that the hydrophilic Nafion coating significantly amplifies EC vortices. Direct visualization revealed that the coating layer acts as an electrical nozzle, inducing intense electric field focusing that triggers macroscopic vortex growth. Furthermore, we visually confirmed that the coating layer physically seals catalytic sites, effectively suppressing parasitic water-splitting reactions. In continuous desalination experiments, this hydrodynamic synergy led to a 32% increase in current efficiency (CE: 1.23) and an 18% increase in salt removal ratio (SRR: 79.4%) compared to bare membranes in the over-limiting regime. These findings demonstrate that inducing controlled hydrodynamic instability via surface modification is a dominant factor for high-efficiency desalination. Full article

Proton exchange membranes (PEMs) are essential for fuel cells, yet conventional materials like Nafion suffer from humidity dependence and limited thermal stability. This study introduces sulfonated phenylene-bridged periodic mesoporous organosilicas (PMOs) as promising inorganic–organic hybrid PEMs, synthesized via surfactant-templating with varying alkyl chain lengths for different mesopore sizes. Post-synthetic functionalization involves nitration of phenylene moieties, reduction to amines, and ring-opening of propane or butane sultones to graft sulfonic acid groups via flexible spacers, achieving homogeneous distribution along pore walls. Post-functionalization is confirmed by powder X-ray diffraction (PXRD), revealing preserved 2D hexagonal p6mm ordering and phenylene stacking. N₂ physisorption shows type IV isotherms with reduced pore volumes and pore sizes. ¹H NMR is used to quantify functionalization degrees. Impedance spectroscopy on pressed pellets demonstrates proton conductivities up to 2 × 10⁻³ S cm⁻¹ at 30 °C and 90% RH, depending on the functionalization degree, confirming sulfonic acid-mediated conduction. Full article

This work provides a systematic experimental study for the electrochemical desalination of saline water using an electrospun permselective polyvinylidene difluoride (PVDF) membrane. Several nano additives were initially screened during membrane development; however, only the materials that demonstrated stable dispersion, reproducible membrane formation, and consistent electrochemical behaviour, namely graphene oxide (GO) and carbon nanotubes (CNTs) were selected for full analysis in this study. Accordingly, the study focuses on pure PVDF, PVDF/GO, and PVDF/CNTs membranes integrated with an alternating Ag/AgCl electrode system. The silver electrode is prepared by spray-coating of silver nanoparticles on high surface carbon cloth, whereas the AgCl electrode was prepared electrochemically from the Ag electrode using a three-electrode electrochemical cell. The electrochemical behaviour of various modified electrodes (bare carbon cloth, Ag/carbon cloth, Ag/nafion/carbon black/PVDF, and Ag/nafion/carbon cloth) was evaluated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and X-Ray Diffraction (XRD). The electrode prepared using Nafion and PVDF as binders with carbon black as conductive additive exhibited the highest current response and lowest charge-transfer resistance. When coupled with this optimized electrode, the PVDF/GO membrane delivered the best desalination performance, achieving an ion removal efficiency of 68%, a salt adsorption capacity (SAC) of 775.40 mg/g, and a specific energy consumption (SEC) of 16.17 kJ/mole values superior to those reported in the literature. Full article

This article reports on how the length of the alkyl chain influences the morphological properties of thiol-stabilized silver nanoparticles (Ag NPs) and their subsequent effects on the performance and durability of proton exchange membrane fuel cells (PEMFCs). We synthesized thiol-stabilized Ag NPs by varying the alkyl chain length: 1-hexane thiol (C6), 1-octanethiol (C8), 1-decanethiol (C10), 1-dodecanethiol (C12), and 1-tetradecanethiol (C14), which we achieved using the two–phase Brust–Schiffrin method. X-ray Diffraction (XRD) patterns confirm the formation of crystalline Ag NPs. A morphological study conducted using a Transmission Electron Microscope (TEM) demonstrated that smaller alkyl chain length thiols (C6, C8, and C10) tend to coalesce, while C12 shows better uniformity with no agglomeration. C14 produces larger nanoparticles. A distinct pressure-area isotherm was observed when Ag NPs were spread at the water/air interface of a Langmuir–Blodgett (LB) trough. After obtaining the monolayer formation pressure range, we coated the Nafion 117 membrane of a polymer electrolyte membrane fuel cell with these nanoparticles to form monolayers of different Ag NPs (C6, C8, C12, C14) at various surface pressures (2 mN/m, 6 mN/m and 10 mN/m). Maximum power output enhancement was observed for C12, while other nanoparticles (C6, C8, C10, C14) did not exhibit noticeable power enhancement for PEMFCs. C12 Ag NPs deposited at surface pressure 6 mN/m give maximum power density increase (26.5%) at the fuel cell test station. In addition, we examined the carbon monoxide (CO) resistance test by mixing 0.1% CO with hydrogen (H2), and C12 Ag NPs showed the highest resistance to CO poisoning. However, no enhancement in power or CO tolerance was observed when C12 Ag NPs were coated by spray coating. These outcomes showcase that alkyl chain length plays a critical role in controlling the size and distribution of thiol-stabilized nanoparticles, which eventually has a direct impact on the performance and CO resistance of PEMFCs when applied to polymer electrolyte (Nafion 117). In addition, surface pressure during monolayer formation controls the distribution of Ag NPs (the distance between nanoparticles at the membrane interface), which is necessary to achieve catalytic activity for power improvement and to prevent platinum (Pt) poisoning by CO oxidation at ambient conditions. Full article