Search Results (2,093)

This study investigates the microstructural, tribological, and corrosion properties of electrodeposited Zn-Co nanocomposite coatings reinforced with graphene and TiO₂ nanoparticles on Selective Laser-Melted (SLM) Ti6Al4V alloy. Systematic characterization using XRD, SEM, and Raman spectroscopy revealed that the incorporation of graphene and TiO₂ significantly refined the grain structure, resulting in a dense and defect-free surface morphology. Reciprocating wear tests demonstrated that the optimized hybrid coating (Zn-Co-GTi) exhibited superior tribological performance. Electrochemical impedance spectroscopy (EIS) tests conducted in simulated body fluid (SBF) at 37 °C demonstrated that the optimized hybrid coating (Zn-Co-GTi) also provided enhanced corrosion resistance. Specifically, the coefficient of friction decreased from 0.79 to 0.24, while the wear rate was reduced to 5.1 × 10⁻⁴ mm³/Nm. Electrochemical evaluations further confirmed a significant improvement in corrosion resistance, with the Zn-Co-GTi coating exhibiting the lowest corrosion current density (0.0059 μA cm⁻²) and the highest charge transfer resistance (Rct). However, increasing the reinforcement content beyond the optimum level resulted in partial nanoparticle agglomeration, leading to a slight deterioration in both tribological and corrosion performance. Overall, the optimized Zn-Co-Graphene-TiO₂ nanocomposite coating provides an effective and scalable surface engineering strategy for improving the durability and corrosion resistance of SLM-produced Ti6Al4V components for advanced engineering and biomedical applications. Full article

Objectives: To evaluate the corrosion behavior and surface characteristics of four nickel-containing orthodontic archwires (stainless steel (SS), superelastic nickel–titanium (NiTi), copper–nickel–titanium (CuNiTi), and multiforce NiTi) under unused, in vitro artificial saliva-immersed, and clinically used (in vivo) conditions. Methods: Rectangular SS, NiTi, CuNiTi, and multiforce NiTi archwires were analyzed in the following three conditions: as received, after one week of immersion in artificial saliva (pH 6.4), and after clinical use for 6–8 weeks. Corrosion behavior was assessed using cyclic voltammetry (CV), open-circuit voltammetry (OCV), and electrochemical impedance spectroscopy (EIS). Surface morphology was examined by scanning electron microscopy (SEM). Results: Corrosion behavior was dependent on archwire type and exposure condition. SS archwires exhibited reduced impedance response after clinical use, indicating passive-film degradation. In the clinically used NiTi specimen, pronounced electrochemical instability was observed, characterized by a deep OCV transient, slow repassivation, and SEM evidence compatible with localized pitting corrosion. In the CuNiTi specimens, minimal differences were observed between the unused and clinically used conditions, which may be consistent with stable passive-film integrity in these specimens. In the multiforce specimen, clinical use was associated with a higher impedance response than the unused and saliva-immersed conditions of that same specimen. In the saliva-immersed specimens, possible passive-film formation and a higher impedance response were observed relative to the other conditions of the same specimens, but these did not reproduce the electrochemical and morphological changes observed after clinical use. Conclusions: In vitro artificial saliva immersion does not reliably replicate in vivo aging of nickel-containing orthodontic archwires. Corrosion behavior evolves during clinical service in an archwire-specific manner, with NiTi archwires showing susceptibility to clinically induced surface degradation. Full article

The growing demand for sustainable, flexible, and high-performance electrode materials for energy storage has motivated the development of polymer-based composite electrodes with enhanced electrochemical properties. In this study, flexible cobalt oxide (Co₃O₄)-iron oxide (Fe₂O₃) nanoparticle-impregnated sodium alginate (NaAlg) as the polymer matrix composite membranes were developed via a simple solution-casting method to exploit the synergistic pseudocapacitive behaviour of mixed metal oxides together with the excellent film-forming ability, flexibility, and eco-friendly nature of NaAlg. The prepared membranes’ structural features, morphology, and electrochemical properties were examined through a set of techniques, such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Universal Testing Machine (UTM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), potentiodynamic polarisation (PDP), and galvanostatic charge–discharge (GCD). Characterisation techniques validated the effective loading of Co₃O₄ and Fe₂O₃ nanoparticles within the NaAlg matrix, and revealed the efficient interfacial interactions, structural integrity, and electrochemical properties of the composites. GCD tests showed a very high specific capacitance of 571.43 F g⁻¹ at 1.2 A g⁻¹. The best-performing electrode produced a top energy density of 155.56 Wh kg⁻¹ at a power density of 2800 W kg⁻¹ and still showed around 91% capacitance retention after 2500 charging–discharging cycles with coulombic efficiency close to 100%. Boosted electrochemical performance is due to the synergistic effect of Co₃O₄-Fe₂O₃ nanoparticles that not only offer plenty of electroactive sites but also help in effective electron and ion transport within the polymer matrix. The results obtained here confirmed the capabilities of Co₃O₄-Fe₂O₃@NaAlg composite membranes as green and potent electrode materials for future supercapacitor devices. Full article

To overcome the problems of poor durability and structural incompatibility inherent in conventional urban traffic monitoring technologies, this study develops a self-sensing asphalt concrete composite incorporating carbon fiber (CF) as a conductive functional filler to construct an internal conductive network. The effects of CF dosage and loading rate on the electrical and dynamic piezoresistive characteristics of the composite were systematically investigated. Furthermore, the evolution mechanism of the micro-conductive network was revealed via electrochemical impedance spectroscopy (EIS) coupled with equivalent circuit modeling. The results demonstrate that the electrical resistivity follows a two-stage percolation behavior (“sharp decline followed by stabilization”) with increasing CF content, yielding a percolation threshold of 0.2 wt%. As CF dosage increases, the Nyquist plots transition from quasi-linear profiles to a fully developed single semicircle, and eventually to an alternating pattern of high-frequency capacitive arcs and low-frequency diffusion impedance. Equivalent circuit analysis reveals that higher CF loadings reduce both contact and tunneling resistances while simultaneously elevating interfacial capacitance. Under monotonic loading, the developed conductive network enables enhanced piezoresistive responses, and the 0.2 wt% group achieves the most pronounced improvement relative to the 0.1 wt% group, with the maximum resistivity change rate and stress sensitivity increasing by 82.05% and 313.59%, respectively. Moreover, the specimens exhibit the optimum piezoresistive response under a dynamic loading rate of 250 N/s. This study clarifies the variable-frequency sensing mechanism of self-sensing asphalt concrete, providing scientific guidance for dynamic speed measurement and weigh-in-motion (WIM) monitoring in smart pavements. Full article

Poly(vinyl alcohol) (PVA)/sodium alginate (SA) dual-network hydrogels were prepared via the freeze–thaw method. Tensile testing, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and fiber-optic spectroscopy were employed for material characterization, and multiple metal ions were screened to optimize mechanical properties and ionic conductivity. The results showed that, at PVA:SA mass ratio of 2:1, the hydrogel achieved 163% elongation and 0.18 MPa tensile strength. Ca²⁺ crosslinking formed an enhanced structure with mechanical properties of 170% elongation and 0.21 MPa strength, and ionic conductivity (0.69 S/m). Combined with colloidal photonic crystal (PC) templates, the PVA/SA-PC film exhibited an inverted opal structure, showing sensitive color response (green to red) and diffraction red-shift toward Ca²⁺. The conductive film could power a small bulb, demonstrating potential for portable visual sensing applications. Full article

The reuse of expired pharmaceuticals as corrosion inhibitors offers a sustainable strategy for reducing pharmaceutical waste while providing environmentally friendly alternatives to conventional inhibitors. In this work, the corrosion inhibition performance of expired ibrutinib (EIB) for P110 carbon steel in 1.0 M HCl was investigated using electrochemical techniques, mass loss measurements, surface characterization, and computational approaches. Electrochemical impedance spectroscopy (EIS) revealed a progressive increase in charge-transfer resistance with increasing inhibitor concentration, while potentiodynamic polarization (PDP) measurements demonstrated that EIB acts as a mixed-type inhibitor with a predominant anodic effect. At 1000 mg L⁻¹, inhibition efficiencies of 88.7%, 96.8%, and 93.3% were obtained from EIS, PDP, and mass loss measurements, respectively. SEM analysis confirmed the formation of a compact and homogeneous protective film on the steel surface, significantly reducing corrosion damage and surface roughness. Density functional theory (DFT), Natural Bond Orbital (NBO), Monte Carlo (MC), and molecular dynamics (MD) simulations demonstrated strong adsorption of EIB on the Fe(110) surface through nitrogen- and oxygen-containing active centers, while radial distribution function analysis confirmed the contribution of chemisorption. The excellent agreement between the experimental and theoretical results demonstrates that expired ibrutinib is an efficient and sustainable corrosion inhibitor for P110 carbon steel in acidic environments and represents a promising approach for the valorization of expired pharmaceutical products. Full article

Hierarchical titanium dioxide (TiO₂) has emerged as a promising photocatalytic material owing to its excellent chemical stability, environmental benignity, low cost, and high density of surface-active sites. Nevertheless, its practical application is constrained by rapid photogenerated charge-carrier recombination and poor visible-light utilization resulting from its wide bandgap. In the present study, a hierarchical TiO₂/CdS quantum dot (QD) nanocomposite was engineered through a facile and cost-effective pseudo-successive ionic layer adsorption and reaction (p-SILAR) technique with controlled CdS QD deposition. The structural, morphological, optical, and electrochemical properties of the synthesized photocatalysts were systematically investigated using SEM, TEM, XRD, XPS, UV-Vis spectroscopy, photoluminescence (PL), and electrochemical impedance spectroscopy (EIS). The results confirmed the successful deposition of highly dispersed CdS QDs onto the hierarchical TiO₂ framework without altering its morphology or crystal structure. The formation of the heterojunction significantly enhanced visible-light absorption and reduced the optical bandgap from 3.19 eV for pristine TiO₂ to 2.37 eV for the TiO₂/CdS QD nanocomposite. Furthermore, PL and EIS analyses demonstrated suppressed electron–hole recombination and improved interfacial charge-transfer characteristics, respectively. Owing to these synergistic effects, the optimized TiO₂/CdS QD photocatalyst achieved 85.3% degradation of methylene blue under visible-light irradiation within 120 min, exhibiting substantially superior performance to pristine hierarchical TiO₂. Radical scavenging experiments revealed that superoxide radicals ^●O₂⁻ and photogenerated holes (h⁺) were the dominant reactive species governing the degradation process. The enhanced photocatalytic activity is attributed to the combined effects of efficient visible-light harvesting, accelerated charge separation, and effective interfacial charge migration across the TiO₂/CdS QD nanocomposite. These findings highlight the potential of hierarchically structured TiO₂/CdS QD nanocomposites as efficient and economically viable photocatalysts for environmental remediation and wastewater treatment applications. Full article

The intrinsic properties of plants offer numerous opportunities for scientific and technological advancement. Considerable efforts have been directed toward developing plant-on-chip platforms to investigate cellular responses to external stimuli, including chemical, mechanical, and electrical cues. In this study, we present a fluidic platform using polydimethylsiloxane (PDMS) and a printed circuit board (PCB), integrated with electrochemical impedance spectroscopy (EIS) detection. Various experimental conditions were examined, including ionic and pH stimulation, as well as membrane dimensions, with the onion inner membrane treated as a black-box system. The measurement results are presented as Nyquist plots, and a resistance model incorporating multifactorial influences is proposed. Impedance variations in plant cells serve as a basis for electrical modulation. To explore these properties, we converted acoustic signals into electrical inputs and recorded the outputs after being modulated by onion inner epidermal cells. A transfer function analysis was subsequently performed. Our results indicate that the plant cell-on-chip (PCOC) platform holds promise for further investigations into plant cell properties. The impedance results suggest that plant cells can respond to different external stimuli, enabling modulation of the electrical properties. These findings lay the groundwork for future studies on cellular electrical characteristics and the development of preliminary bioelectrical circuits. Full article

The formation of anti-permeability is a critical step in the in-situ repair of organic anti-corrosion coatings under seawater, yet it is significantly influenced by the surrounding marine environment, particularly seawater temperature and applied cathodic polarization potential. In this study, we systematically investigated the effects of temperature and cathodic polarization potential on the permeability of curing epoxy coatings in simulated shallow seawater. Our results demonstrate that the anti-permeability formation process is governed by the competition between seawater penetration and coating curing. At lower temperatures, the EIS-derived evolution of coating resistance suggested heterogeneous electrolyte uptake across the coating surface, whereas at elevated temperatures, the electrochemical response indicated a more uniform progression of ionic ingress. Moreover, enhanced cathodic polarization accelerated both seawater penetration and the curing reaction of the epoxy coating. The underlying mechanisms of temperature- and polarization-dependent permeability formation were discussed in detail, providing theoretical insights into the top-down permeation process during underwater curing, which may inform the development of more effective in situ repair strategies for organic coatings. Full article

Electrochemical parameter identification is crucial for evaluating the electrochemical processes in proton exchange membrane water electrolysis (PEMWE). Conventional characterization techniques-including polarization-curve fitting, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and current interruption (CI)-face significant limitations for rapid diagnostics under high-current dynamic operation, arising from constraints in instrument current rating, measurement time, zero-current control, and noise amplification in numerical differentiation. In this study, we present a simple current step (CS) method to accurately identify key electrochemical parameters and perform overpotential breakdown by using a simplified equivalent circuit model with a current source. To address the numerical instability in derivative calculation caused by sampling noise during voltage transient analysis, a physics-informed neural network (PINN) is introduced to enhance signal smoothness while guaranteeing physical consist ency. Compared with standard characterization, the proposed CS-PINN method demonstrates high accuracy, with an error of less than 2% in overpotential breakdown, less than 5.3% in ohmic resistance, and 2.8% in the Tafel slope (at 5 A/cm²). These results confirm that the CS-PINN method provides a fast, accurate, and equipment-friendly route for rapid electrochemical parameter identification in PEMWE. Full article

Electrochemical impedance spectroscopy (EIS) resolves the internal physicochemical processes of lithium-ion batteries across timescales—from ohmic conduction through charge-transfer kinetics to solid-state diffusion. Despite this analytical power, EIS deployment remains largely confined to laboratory electrochemical workstations that are bulky, expensive, and incapable of online multi-cell operation under dynamic DC bias conditions. This study presents a multi-channel EIS measurement device that simultaneously addresses three requirements for practical battery diagnostics: workstation-grade measurement accuracy, multi-cell synchronous acquisition, and tolerance to the DC bias voltage present across battery terminals during operation. The device employs a master–slave distributed architecture: each slave unit is built around the DNB1101 battery-dedicated impedance measurement chip with a Kelvin four-wire sensing configuration, while the STM32F407-based master controller coordinates measurement scheduling and data communication under FreeRTOS. A four-channel slave board with a differential daisy-chain communication topology and hardware broadcast trigger mechanism supports multi-cell synchronous acquisition. The device operates over a frequency range of 0.01 Hz to 5620 Hz with logarithmic spacing, and a C#-based host application provides real-time Nyquist and Bode visualization along with MATLAB R2024a-based post-processing for outlier rejection and data smoothing. Validation was conducted using Panasonic NCR18650 ternary (NCA) and LiFePO₄ (LFP) 18650 cells, benchmarked against a CorrTest CS350 electrochemical workstation at SOC = 40% and 25 °C. The device achieves a maximum impedance magnitude error of 1.55% and a maximum phase error of 1.22%. Equivalent circuit model fitting via ZSimpWin yields parameter differences below 1% between the device and the reference workstation. Under online conditions with a 3.6 V DC bias, the impedance measurement deviation of a 20 mΩ precision resistor remains below 0.69% across the full frequency range. Multi-channel synchronous measurements across four cells demonstrate inter-channel amplitude variance below 2.13%. Cross-chemistry validation with LiFePO₄ cells yields magnitude and phase errors below 0.92%. These results demonstrate that the proposed device provides laboratory-grade EIS accuracy with multi-channel, online, and cross-chemistry capabilities, offering a practical platform for integrating EIS-based diagnostics into next-generation battery management systems. Full article

To address the challenges of weak NO₃⁻ adsorption, insufficient active hydrogen supply, and facile desorption of NO₂⁻ intermediates in neutral electrocatalytic nitrate reduction reaction (NO₃RR), this study employs laser nano-welding technology to fabricate a Ru/WO₃ heterojunction, and constructs a Ru/WO₃/Cu(OH)₂/FC spatially confined electrode using Cu(OH)₂ nanorod arrays as the support. Laser welding achieves metallurgical-grade bonding between Ru and WO₃ while retaining oxygen vacancies in WO₃. Cu(OH)₂ promotes NO₃⁻ adsorption via electrostatic and Lewis acid interactions, and its nanorod array structure confines NO₂⁻ intermediates. In 0.5 M K₂SO₄ + 50 mM KNO₃ electrolyte, the electrode delivers an ammonia yield rate of 16.1 mg h⁻¹ cm⁻² and a Faradaic efficiency of 75.8% at −0.8 V vs. RHE, outperforming control groups. Potential-dependent electrochemical impedance spectroscopy (EIS) confirms that spatial confinement suppresses NO₂⁻ accumulation and optimizes interfacial charge transfer kinetics, providing a new strategy for electrode design in neutral NO₃RR. Full article

Biodegradable Mg–Ca–Sr alloys are promising candidates for temporary implant applications, but their degradation behavior is strongly influenced by alloy composition and electrolyte chemistry. This comparative short-term study investigated how increasing the Sr content from 0.5 to 1.5 wt.% influences the electrochemical response and surface characteristics of cast Mg–0.5Ca–xSr alloys in 0.9% NaCl and calcium- and magnesium-free Dulbecco’s phosphate-buffered saline (DPBS). Potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy, quantitative image analysis, and energy-dispersive X-ray spectroscopy were used. Increasing the Sr content reduced the corrosion-current density from 0.0110 to 0.0039 mA/cm² in NaCl and from 0.297 to 0.169 mA/cm² in DPBS, while the corresponding calculated corrosion rates decreased from 2.51 to 0.886 mm/year and from 6.66 to 3.79 mm/year, respectively. Replicated EIS measurements of both alloys showed that Mg–0.5Ca–1.5Sr exhibited higher charge-transfer resistance than Mg–0.5Ca–0.5Sr in both NaCl (253 ± 15 versus 184 ± 14 Ω·cm²) and DPBS (853 ± 48 versus 615 ± 42 Ω·cm²). NaCl-exposed surfaces showed more porous and discontinuous deposits and a greater number of visible pit-like defects, whereas DPBS produced comparatively continuous P-containing deposits. Overall, increasing the Sr content to 1.5 wt.% was associated with lower polarization-derived global corrosion kinetics and a more resistive interfacial response, whereas electrolyte composition strongly influenced both interfacial impedance and surface-deposit morphology. These findings represent comparative short-term electrochemical and surface-characterization data obtained at 23 ± 1 °C and should not be interpreted as measures of long-term physiological degradation or in vivo performance. Full article

The electrification of commercial vehicles demands precise battery thermal management, but direct measurement of the cell core temperature is challenging. This paper presents an electrochemical impedance spectroscopy (EIS)-based approach for rapid indirect estimation of the mean internal temperature in 2170 NMC lithium-ion cells. Three measurement approaches and various fitting methods, including Steinhart–Hart, least-squares polynomials, and nonlinear Arrhenius-based fits, are compared using experimental data. The results indicate that estimation accuracy is more strongly influenced by the selection of measurement frequency than by the choice of fitting approach. The optimal method combines a single optimized frequency with a nonlinear polynomial incorporating an Arrhenius term, achieving a maximum deviation of $0.23\mathrm{K}$ and a mean deviation of $0.14\mathrm{K}$. This framework enables indirect EIS-based estimation of the cell core temperature and can be further refined through measurements on multiple cells or by combining different fitting methods. Future work should extend the proposed approach to dynamic EIS measurements, battery ageing, and integration with thermal models for early overheating warning and identification of the first thermal runaway warning stage in high-power commercial vehicles. Full article

This study investigates the efficacy of Reserpine (RZ), a natural indole alkaloid, that serves as a sustainable inhibitor of corrosion for OLC52 and aluminum in a 0.5/0.25 mol L⁻¹ acetic acid/potassium acetate solution, relevant to de-icing applications. The electrochemical methods used in this study included cyclic (CV) and linear sweep voltammetry (LSV), chronoamperometry (CA) and electrochemical impedance spectroscopy analysis (EIS), and allowed for the determination of the necessary parameters for the evaluation of the adsorption behavior. In addition to electrochemical studies, theoretical molecular modeling calculations were also carried out. The results indicate that RZ reduces the corrosion rate at the highest tested concentration of 10⁻³ M RZ, reaching inhibitory efficiencies of 90% for OLC52 and 94% for Al. The adsorption aspects have been described by the Langmuir and Freundlich isotherms, whose $∆G_{ads}^o$ resulting values suggest a physicochemical adsorption by forming a compact and protective layer. Molecular modeling demonstrates RZ’s ability to interact with metal surfaces taken into action through both donor–acceptor and electrostatic interactions, highlighting the potential of RZ as a green corrosion inhibitor in similar environments, usable in de-icing solution formulations. Full article