Search Results (3,115)

Facing the increasingly scarce supply of rare-earth resources, a cobalt-doped metal–organic framework-derived carbon–metallic sulfide composite (Co-FeS₂@C) was successfully synthesized via the hydrothermal method and the following carbonization/sulfidation treatments and used for the efficient electrosorption of rare earths from aqueous solution. Comparative characterizations revealed that Co doping effectively expanded the interlayer spacing of FeS₂, introduced crystalline defects, and optimized the electronic structure, thereby synergistically enhancing active site exposure and electron transfer kinetics. In addition, the electrochemical analysis demonstrated a significant increase in the surface-controlled capacitive contribution from 57.1% to 83.3%, indicating the markedly improved electric double-layer effects and mass transport efficiency. Under the optimal conditions, the Co-FeS₂@C electrode achieved a high Yb³⁺ adsorption capacity of 129.2 mg g⁻¹ along with an exceptional cycling stability (92.63% retention after 20 cycles), substantially outperforming the undoped counterpart FeS₂ (88.4 mg g⁻¹ and 74.61%). Furthermore, the mechanistic investigations confirmed that the electrosorption process follows a monolayer physico-chemical synergistic mechanism, primarily driven by the pseudo-capacitive effect arising from the redox reaction of FeS₂ and the enhanced charge-transfer driving force resulting from the higher electronegativity of cobalt. This work provides an innovative electronic structure modulation strategy for developing the high-performance capacitive deionization electrodes for rare earth recovery via the electrosorption process. Full article

Cell analysis is vital in clinical diagnostics and cell engineering research. Among the various analytical techniques, dielectrophoresis (DEP) is a particularly promising label-free method for distinguishing biological particles, which eliminates the need for fluorescent dyes or magnetic beads. In this study, we present a high-precision single-cell analysis system based on the evaluation of DEP forces in a controlled microfluidic flow environment. The system integrates a microfluidic chamber equipped with an electrode array to exert DEP forces and flow-induced shear forces to facilitate force balance analysis. We quantitatively characterized the DEP response to successfully discriminate between healthy skin cells and cancer cells using the proposed DEP-based cell-sorting platform. The proposed system successfully distinguished between these cell types even when their dielectrophoretic properties were similar, highlighting its potential for sensitive and selective cell classification in biomedical applications. Full article

In the whole-angle mode of a hemispherical resonator gyro (HRG), the external input rotation angle is obtained by detecting the standing-wave rotation angle through electrodes. Due to this operational principle and manufacturing constraints of HRGs, the gyro output in an HRG inertial navigation system exhibits angle-dependent errors that are highly sensitive to temperature variations. To address this issue, this paper proposes a system-level calibration scheme to characterize and compensate for these correlated errors. Angle-dependent bias models were established through multi-temperature point experiments. A Kalman filter was subsequently designed, and a calibration path satisfying observability requirements was developed. System-level calibration experiments were conducted to determine and compensate for the identified errors. Finally, navigation experiments demonstrated the effectiveness of the proposed method, showing that the navigation accuracy of the HRG inertial navigation system was improved by up to 94.35%. Full article

The article reports for the first time the application of a solid silver microelectrode array for the anodic stripping voltammetric determination of thallium(I) ions (Tl(I)). The microelectrode properties of the presented sensor were tested. The proposed solid metal microelectrode array is characterized by its eco-friendly nature due to the use of non-toxic electrode material. The advantage of this procedure is that no surface modification of the microelectrode was required. The optimization of the procedure for determining Tl(I) was performed. The experimental parameters (e.g., pH of supporting electrolyte, conditions of activation step, potential and time of deposition, effects of possible interferences) were investigated. The dependence of the thallium peak current on its concentration was linear in the range from 5 × 10⁻¹⁰ to 1 × 10⁻⁷ mol·L⁻¹ (deposition time of 120 s). The estimated detection limit was 1.35 × 10⁻¹⁰ mol·L⁻¹. The repeatability of the procedure expressed as RSD% for a Tl(I) concentration of 2 × 10⁻⁸ mol·L⁻¹ was 3.6% (n = 5). The proposed procedure was applied for determining Tl(I) in certified reference materials and for studying recovery in the environmental water sample. The obtained results indicated the possibility of an analytical application of the elaborated procedure in practice. Full article

This work presents the fabrication and analytical application of nanostructured Ni-zeolite (NiZY) and carbon nanohorns (CNHs) modified glassy carbon electrode (NiZY/CNHs-GCE) in the differential pulse voltammetric (DPV) determination of vitamin B₂ (VB₂) molecules. The synergistic combination of NiZY and CNHs significantly enhances the electrochemical performance of the sensor, as confirmed by structural, textural, morphological, and electrochemical studies. The redox behavior of VB₂ on NiZY/CNHs-GCE was found to be adsorption-controlled, involving a two-electron, two-proton reversible reduction process. Under optimized conditions, the DPV response of NiZY/CNHs-GCEs in McIlvaine buffer solution (pH 3.4) exhibited a linearity in the VB₂ concentration range of 0.01 to 0.20 mg L⁻¹ (r = 0.9993) with a detection limit of 3.2 µg L⁻¹ (8.6 × 10⁻⁹ mol L⁻¹). Furthermore, well-resolved reduction peaks of vitamins B₂ and B₉ (VB₉) enabled their simultaneous and selective detection, with linear ranges of 0.01 to 0.20 mg L⁻¹ for VB₂ and 0.01 to 0.16 mg L⁻¹ for VB₉. The proposed analytical method, characterized by high selectivity and robustness, was successfully applied in the determination of both vitamins in commercially available dietary supplements, achieving relative errors within −6.2% to 2.7%. Full article

Hepatitis C represents a critical global health crisis, causing approximately 1.4 million deaths annually. Although 98% of cases are treatable, only about 20% of infected individuals know their hepatitis C virus (HCV) status, highlighting the urgent need for rapid and more efficient diagnostic management. Viral genetic material can be detected in serum or plasma within just one week of exposure, making it the most reliable marker and the gold standard for active HCV infection diagnosis. In this study, a biosensor was developed to detect conserved nucleotide sequences of HCV using a 3D surface electrode composed of poly-L-lysine (PLL) and carbon nanotubes (CNTs). PLL is a positively charged biocompatible polymer rich in amine groups, attractive for the immobilization of proteins, DNA, and other biomolecules. PLL was employed to construct a 3D surface with vertically aligned CNTs, achieving a high electron transfer rate. Cyclic voltammetry technique and scanning electron microscopy (SEM) were used to characterize the sensor platform, and analytical responses were measured by differential pulse voltammetry. This HCV biosensor detected the hybridization event by a significant reduction in DPV peaks in the presence of the ferri/ferrocyanide redox probe, without any intercalator agents. DNA responses were observed in phosphate-buffered saline (PBS) and cDNA-spiked serum samples, demonstrating its analytical specificity. These findings represent advances in analytical tools that can effectively address the challenges of timely diagnosis for asymptomatic HCV carriers. Full article

The oxygen reduction reaction (ORR) is a crucial process in electrochemical systems, such as fuel cells, as it effectively converts oxygen into water, thereby contributing significantly to sustainable energy generation. In this study, copper oxide (CuO) thin films were deposited onto silver (Ag) substrates using a modified successive ionic layer adsorption and reaction (SILAR) method, followed by an investigation of their electrocatalytic performance toward ORR in an alkaline medium. Comprehensive electrochemical characterizations, including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and open circuit potential (OCP), were employed to evaluate catalyst behaviour. Elemental analysis through energy-dispersive X-ray spectroscopy (EDX) confirmed the uniform distribution of CuO, while scanning electron microscopy (SEM) revealed a sponge-like surface morphology which potentially enhances catalytic efficiency. Moreover, EIS spectra revealed a lower charge transfer resistance for the CuO/Ag electrode (3.37 kΩ) compared to bare Ag (4.23 kΩ), reflecting improved ORR kinetics. Among different deposition cycles, 15 SILAR cycles yielded the highest current density of 0.8 mA cm⁻² at 0.60 V. Kinetic analysis revealed that the reaction is irreversible, with a lower value of Tafel slope (32 mV dec⁻¹) and high transfer coefficient (α = 0.45), indicating a concerted reduction mechanism. The ORR pathway was found to follow a four-electron (4e⁻) transfer process. Full article

Different morphologies of cobalt oxide (Co₃O₄) electrodes were prepared through the electrochemical deposition technique with various electrodeposition times from 10 min to 50 min. Platinum (Pt) nanoparticles were deposited on the Co₃O₄ electrodes through sputter coating. The crystallographic, microstructural, surface functional, textural–structural, and electric properties of the Co₃O₄ electrodes were investigated. X-ray diffraction analysis identified a pure cubic Co₃O₄ crystal structure in the samples. In the electrodeposition process, the microstructure of the electrodes varied from hierarchical 3D flower-like to 2D hexagonal porous nanoplates due to an increase in oxygen vacancies. The carrier densities of all samples were between 5.77 × 10¹⁴ cm⁻³ and 8.77 × 10¹⁴ cm⁻³. The flat band potentials of all samples were between −5.91 V and −6.21 V vs. an absolute electron potential, and the potential values for electrodes became more positive as the oxygen vacancy concentration in the film structure increased. The 2D hexagonal porous nanoplate Pt/Co₃O₄ electrodes offered the highest oxygen vacancies and thus the maximum current density of 102.66 mA/cm², with an external potential set at 1.5 V vs. an Ag/AgCl reference electrode. Full article

High-quality powders with spherical particles and controllable properties can be produced using centrifugal force. This review provides a comparative analysis of two centrifugal atomization techniques: the plasma rotating electrode process (PREP) and centrifugal atomization (CA). It systematically examines the fundamental principles, film disintegration modes, and the resultant powder characteristics, with a focus on mechanisms that lead to common defects. By evaluating current technological limitations and highlighting potential pathways for advancement, this review aims to offer valuable insights for the future development of high-quality, spherical metal powders for advanced manufacturing applications. Full article

Perfluorooctanesulfonate (PFOS) is a typical persistent organic pollutant, which presents a significant risk to the ecosystem and human health. Therefore, the development of a highly sensitive and effective detection technique for PFOS has aroused wide concern. In this study, for the mesoporous metal–organic frameworks (MOFs), Cr-MIL-101 were used as the precursor. And the poly(3,4-ethylenedioxythiophene) (PEDOT) using as molecularly imprinted polymers (MIPs) was loaded on Cr-MIL-101 to form a core–shell structure. The obtained Cr-MIL-101@PEDOT/MIP composites integrate the high specific surface area of Cr-MIL-101 and the specific recognition capability of PEDOT/MIP. The glassy carbon electrode (GCE) interface modified by them can specifically adsorb PFOS through electrostatic interactions, coordination by Cr metal nodes, hydrophobic interaction, and hydrogen bonding, etc. The adsorbed PFOS molecules could block the active sites at the electrode interface, causing the current decay of the redox probe. Following the quantitative analysis of peak current decay values using the Langmuir model and the Freundlich–Langmuir model, a wide detection range (0.1–200 nM) and a low detection limit (0.025 nM) were obtained. Characterization techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), and electrochemical methods were employed to validate the fabrication of the composites. Moreover, Cr-MIL-101@PEDOT/MIP/GCE showed satisfactory stability, repeatability, and selectivity, providing an effective method for the detection of PFOS in practical samples, showing a wide prospective application. Full article

The development of porous carbon materials that meet the demands of commercial supercapacitors is challenging, primarily due to the requirements for high energy and power density, as well as large-scale manufacturing capabilities. Herein, we present a sustainable and cost-effective method for synthesizing N–O–S co-doped hierarchical porous carbons (designated as ALK_x) from ammonium lignosulfonate (AL), an industrial by–product. This process employs a low KOH/AL mass ratio (x ≤ 0.75) and a carbonization temperature of 900 °C. The resulting materials, ALK₀.₅₀ and ALK_0.75, exhibit an exceptionally high specific surface area (>2000 m² g⁻¹), a well-balanced micro-mesoporous structure, and tunable heteroatom content, which collectively enhance their electrochemical performance in both aqueous and ionic liquid electrolytes. Notably, ALK_0.75 features a heteroatom content of 13.2 at.% and a specific surface area of 2406 m² g⁻¹, owing to its abundant small mesopores. When tested as an electrode in a two–electrode supercapacitor utilizing a 6 M KOH electrolyte, it achieves a high specific capacitance of 250 F g⁻¹ at a current density of 0.25 A g⁻¹ and retains 197 F g⁻¹ even at 50 A g⁻¹, demonstrating remarkable rate capability. In contrast, ALK_0.50, characterized by a lower heteroatom content and an optimized pore structure, exhibits superior compatibility with the ionic liquid electrolyte EMIMBF₄. A symmetric supercapacitor constructed with ALK_0.50 electrodes attains a high energy density of 90.2 Wh kg⁻¹ at a power density of 885.5 W kg⁻¹ (discharge time of 60 s). These findings provide valuable insights into heteroatom doping and the targeted regulation of pore structures in carbon materials, while also highlighting new opportunities for the high-value utilization of AL. Full article

Electrocatalytic conversion of CO₂ to high-energy-density multicarbon products (C₂₊) offers a sustainable route for renewable energy storage and carbon neutrality. Precisely modulating Cu-based catalysts to enhance C₂₊ selectivity remains challenging due to uncontrollable reduction of Cu^δ+ active sites. Here, an efficient and stable Ge/Cu catalyst was developed for CO₂ reduction to ethanol via Ge modification. A Cu₂O/GeO₂/Cu core–shell composite was constructed by controlling Ge doping. The structure–performance relationship was elucidated through in situ characterization and theoretical calculations. Ge⁴⁺ stabilized Cu¹⁺ active sites and regulated the surface microenvironment via electronic effects. Ge modification simultaneously altered CO intermediate adsorption to promote asymmetric CO–CHO coupling, optimized water structure at the electrode/electrolyte interface, and inhibited over-reduction of Cu^δ+. This multi-scale synergistic effect enabled a significant ethanol Faradaic efficiency enhancement (11–20%) over a wide potential range, demonstrating promising applicability for renewable energy conversion. This study provides a strategy for designing efficient ECR catalysts and offers mechanistic insights into interfacial engineering for C–C coupling in sustainable fuel production. Full article

This study investigates the influence of magnetic fields on the electrochemical corrosion behavior of aerospace-grade H62 brass alloy in 3.5 wt% NaCl solution and its underlying 10 mechanisms. Employing electrochemical testing techniques combined with surface characterization methods, we explored the effects of magnetic field intensity (25–100 mT) and orientation (parallel and perpendicular to electrode surface) on the corrosion kinetics and corrosion product evolution of H62 brass alloy. Results demonstrate that magnetic fields significantly accelerate the corrosion process of H62 brass alloy. Under parallel magnetic field (100 mT), the corrosion current density increased from 0.49 μA/cm² to 3.66 μA/cm², approximately 7.5 times that of the non-magnetic condition, while perpendicular magnetic field increased it to 1.73 μA/cm², approximately 3.5 times the baseline value. The charge transfer resistance decreased from 3382 Ω·cm² to 1335 Ω·cm². Magnetic field orientation determines the fundamental differences in corrosion acceleration mechanisms. Parallel magnetic fields primarily enhance mass transfer processes through Lorentz force-driven magnetohydrodynamic (MHD) effects, resulting in intensified uniform corrosion; perpendicular magnetic fields alter interfacial ion distribution through magnetic gradient forces, inducing localized corrosion tendencies. Magnetic fields promote the transformation of protective Cu₂O films into porous Cu₂(OH)₃Cl, reducing the protective capability of corrosion product layers. Full article

This work introduces a novel approach to enhancing the performance of zinc anodes in zinc–air batteries through a photopolymerizable organic–inorganic hybrid coating. Electrochemical tests were conducted in a neutral NaCl electrolyte, selected to minimize electrolyte carbonation, anode corrosion, and zinc dendrite formation. The behavior of bare and coated zinc electrodes was investigated using linear sweep voltammetry, electrochemical impedance spectroscopy (EIS), potentiostatic measurements, galvanostatic discharge tests, and charge-discharge tests, while morphological and structural characterizations were carried out by Atomic Force Microscopy (AFM), Raman spectroscopy, and X-ray Diffraction (XRD). The results confirmed that the hybrid coating acts as a corrosion-resistant barrier, enhancing the reversibility and stability of zinc electrodes through a barrier mechanism. Charge–discharge tests further confirmed the improved performance of the coated electrode, obtaining at a current density of 1 mA/cm², a coulombic efficiency of 92.61% and a capacity retention of 90.18%, respectively, after 16 cycles. These findings highlight the effectiveness of the photopolymerizable hybrid coating in improving the durability and rechargeability of zinc–air batteries. Full article

Although total knee replacements have an insignificant impact on patients’ mobility and quality of life, real-time performance monitoring remains a challenge. Monitoring the load over time can improve surgery outcomes and early detection of mechanical imbalances. Triboelectric nanogenerators (TENGs) present a promising approach as a self-powered sensor for load monitoring in TKR. A TENG was fabricated with dielectric layers consisting of Kapton tape and 3D-printed thermoplastic polyurethane (TPU) matrix incorporating CNT and BTO fillers, separated by an air gap and sandwiched between two copper electrodes. The sensor performance was optimized by varying the concentrations of BTO and CNT to study their effect on the energy-harvesting behavior. The test results demonstrate that the BTO/TPU composite that has 15% BTO achieved the maximum power output of 11.15 μW, corresponding to a power density of 7 mW/m², under a cyclic compressive load of 2100 N at a load resistance of 1200 MΩ, which was the highest power output among all the tested samples. Under a gait load profile, the same TENG sensor generated a power density of 0.8 mW/m² at 900 MΩ. By contrast, all tested CNT/TPU-based TENG produced lower output, where the maximum generated apparent power output was around 8 μW corresponding to a power density of 4.8 mW/m², confirming that using BTO fillers had a more significant impact on TENG performance compared with CNT fillers. Based on our earlier work, this power is sufficient to operate the ADC circuit. Furthermore, we investigated the durability and sensitivity of the 15% BTO/TPU samples, where it was tested under a compressive force of 1000 N for 15,000 cycles, confirming the potential of long-term use inside the TKR. The sensitivity analysis showed values of 37.4 mV/N for axial forces below 800 N and 5.0 mV/N for forces above 800 N. Moreover, dielectric characterization revealed that increasing the BTO concentration improves the dielectric constant while at the same time reducing the dielectric loss, with an optimal 15% BTO concentration exhibiting the most favorable dielectric properties. SEM images for BTO/TPU showed that the 10% and 15% BTO/TPU composites showed better morphological characteristics with lower fabrication defects compared with higher filler concentrations. Our BTO/TPU-based TENG sensor showed robust performance, long-term durability, and efficient energy conversion, supporting its potential for next-generation smart total knee replacements. Full article