The increasing scarcity of freshwater resources demands the development of efficient and sustainable desalination technologies. In this work, cobalt hexacyanoferrates (CoHCFs), a class of Prussian blue analogs, are investigated as redox-active materials for electrochemical desalination. CoHCF(II) and CoHCF(III) were synthesized and characterized, revealing highly crystalline open-framework structures with mixed-valence states that enable reversible Na⁺ insertion. Electrochemical results demonstrate a desalination mechanism based on faradaic processes, leading to enhanced ion selectivity and salt removal capacity (SRC) compared to conventional carbon-based electrodes. CoHCF(II) exhibited superior SRC after redox cycles due to its greater availability of redox-active sites and structural order, which promote higher Na+ insertion capacity. Desalination tests in a hybrid cell (CoHCF(II)/activated carbon) showed a strong dependence on current density, with a trade-off between capacity and kinetics. An optimal balance between efficiency (267.9 mg NaCl/g) and operation time (3.08 h) was obtained at 100 mA/g after five cycles. These findings highlight CoHCF(II) as a promising material for next-generation electrochemical desalination, offering high capacity, selectivity, and tunable performance governed by both thermodynamic and kinetic factors.
Aqueous zinc-ion batteries (AZIBs) have been the focus of significant research interest in the field of energy storage at an extensive scale; however, their practical application remains constrained by the slow diffusion rate of Zn2+ and limited utilization of active sites in cathode materials. Herein, an iodine-doping strategy is developed to modulate the crystal and electronic structure of iodine-doped Na2V6O16·3H2O (INVO) via a one-step hydrothermal route. The incorporation of iodine has been shown to induce abundant oxygen vacancies and to enlarge the interlayer distance, which synergistically accelerates charge transfer and increases Zn2+ diffusion kinetics. The optimized electrode demonstrates significant advantages in terms of structure and electronics, which contribute to its exceptional performance. It exhibits a considerable capacity of 582.2 mAh g-1 at 0.1 A g-1, a notable rate capability of 470.6 mAh g-1 at 1 A g-1, and high cycling stability with 90.3
This study presents the synthesis and characterization of carbon nanotubes (CNTs)using Co-MgO Catalyst. The catalyst was prepared through a solution combustion method, and CNT growth was achieved through chemical vapour deposition (CVD).The synthesized materials were characterized using X-ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive x-ray Analysis (SEM-EDX), Transmission Electron Microscopy (TEM), TGA and Raman spectroscopy. XRD pattern confirmed good crystallinity, with characteristic peaks corresponding to Co at 31.34°, 36.26°, 62.16°, and 78.35°, and MgO at 42.79°. The results demonstrate that the Co-MgO Catalyst exhibits strong catalytic activity, promoting the formation of high-quality CNTs with uniform morphology, high crystallinity, and low defect density, The study highlights the effectiveness of the catalyst in controlling nanotube growth and improving synthesis efficiency. The synthesized CNTs show promising potential for application in electrochemical detection of glucose.
Accurate modeling of the open-circuit potential (OCP) is essential for lithium-ion battery simulation, state estimation, and electrode design. This work presents two physics-informed neural network (PINN) formulations: a Direct OCP PINN and a Free-Energy PINN for learning thermodynamically consistent OCP functions from noisy synthetic data. The Direct PINN maps stoichiometry to voltage with physics-based regularization, while the Free-Energy PINN learns the Gibbs free energy and derives OCP through automatic differentiation, thereby enforcing thermodynamic consistency by construction. Both architectures are benchmarked against polynomial regression, cubic splines, Nernst-polynomial hybrids, Redlich-Kister expansions, and Gaussian process regression across three representative electrode chemistries: graphite (LiₓC₆), NMC811 (LiₓNi₀.₈Mn₀.₁Co₀.₁O₂), and LFP (LiₓFePO₄). The Free-Energy PINN achieves competitive accuracy (RMSE = 0.009–0.027 V) while also providing physically meaningful free-energy landscapes and thermodynamic derivatives that are not available from purely data-driven models. Complementary analyses quantify the sensitivity of both formulations to the loss-weight selection, their robustness to elevated and serially correlated measurement noise, their extrapolation behavior outside the sampled stoichiometry window, and their computational cost. These results demonstrate that embedding thermodynamic structure into neural network architectures yields interpretable, generalizable OCP surrogates for electrochemical modeling.
High-entropy oxides (HEOs) have been regarded as promising anode materials for lithium-ion batteries (LIBs) because their multi-element composition can facilitate the formation of multicomponent solid solutions and simultaneously regulate the lattice structure, defect chemistry and electrochemical reaction kinetics. In this study, two high-entropy spinel oxides (HESOs), namely (Fe0.3Cr0.3Mn0.2Zn0.1Ni0.1)3O4 and (Fe0.2Cr0.2Mn0.2Zn0.2Ni0.2)3O4 were synthesized using metal-organic frameworks (MOFs) as templates. They were prepared via a hydrothermal method followed by high-temperature annealing at 900 ℃, and their electrochemical performance as anode materials for LIBs was investigated. The results show that (Fe0.3Cr0.3Mn0.2Zn0.1Ni0.1)3O4 exhibits excellent lithium storage performance. Specifically, after 200 cycles at a current density of 0.2 A/g, the discharge specific capacity of (Fe0.3Cr0.3Mn0.2Zn0.1Ni0.1)3O4 remains at 777.9 mAh/g, which is much higher than the 295.6 mAh/g of (Fe0.2Cr0.2Mn0.2Zn0.2Ni0.2)3O4. It also maintains excellent rate capability, retaining 215 mAh/g even at a high current density of 5 A/g. This study demonstrates that rational non-equimolar compositional regulation can simultaneously tune the lattice structure, particle morphology and electrochemical kinetics of high-entropy spinel oxides, thereby providing evidence for a composition-dependent multi-cation synergistic effect.
Self-doping is an effective strategy for introducing defects in metal oxides such as Nb2O5, thereby modifying their electrochemical properties. The formation of defects, such as oxygen vacancies, has been associated with decreased surface charge-transfer resistance and increased charge-carrier density. While this approach has been explored for TiO2 based materials, Nb2O5 remains less investigated in the literature. In this study, we investigate the effect of self-doping in Nb2O5 films obtained by plasma electrolytic oxidation (PEO) and its influence on later surface modification via silver deposition. The Nb2O5 films are produced by PEO using two different electrolyte solutions, oxalic acid and phosphoric acid, at parameters of 20 mA cm-2 and 15 ºC. The anodized samples are subsequently subjected to cathodic polarization (-1 V vs SHE for 150 s). Both pristine and self-doped samples are immersed in a silver nitrate solution at room temperature for 30 min. The samples are characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), Raman spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results reveal variations in morphology and composition, with samples anodized in phosphoric acid showing phosphorus incorporation from the electrolyte. Prior-reduced-anodized samples show different silver incorporation, at a significantly higher level in the sample anodized in oxalic acid ( 18 at.
Y-doped BaZrO3 (BZY) is a promising electrolyte for protonic ceramic fuel cells, but its poor sinter-ability usually requires high-temperature treatment and may cause phase instability. In this work, BZY electrolytes containing 1 wt
NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) is a promising solid electrolyte for all-solid-state batteries, yet interfacial instability and limited mechanical robustness hinder practical deployment. We use first-principles calculations to examine the effect of substituting Al3+ with Mg2+ or Ca2+, with charge compensation from additional Li+, on the properties of LATP. Mg- and Ca-substituted compositions remain thermodynamically stable, and Ca substitution is energetically preferred. Both dopants leave the electronic structure nearly unchanged. Nudged elastic band (NEB) calculations show that Mg and Ca both reduce the Li+ migration barrier relative to pristine LATP and thus improve ionic transport. Ca substitution produces a larger lattice expansion ( 3
Analysis of the existing literature on lead(IV) oxide (PbO2) has revealed several important gaps: i) the absence of a systematic approach and detailed consideration of coating formation kinetics; ii) limited discussion of methanesulfonate electrolytes specifically in the context of electrocatalyst synthesis (as opposed to their use for energy storage materials); iii) the lack of a clear description of the mechanisms of dopant and surfactant incorporation, particularly regarding their applicability in various electrochemical systems. To address these gaps, this review is structured into three key sections. The first section, Electrodeposition, puts a special emphasis on micromodified materials, composites, and systems incorporating surfactants and polyelectrolytes, including kinetic aspects of coating formation. The second section, Physicochemical Properties, covers morphology, texture, phase composition, and recent advances in X-ray photoelectron spectroscopy analysis. The third section, Electrocatalysis, provides a comprehensive overview of electrocatalytic activity in oxygen and ozone evolution, and the oxidation of organic compounds. We are confident that this review, due to its systematic character and focus on fundamental aspects (kinetics, mechanisms, and structure–activity relationships), will be valuable to a broad research community and will serve as a meaningful contribution to the theory of electrocatalysis.
Developing sensing interfaces that simultaneously integrate catalytic activity, efficient charge transfer, and structural stability remains a major challenge for high-performance non-enzymatic glucose sensing. Herein, a CuS/Ti₃C₂/rGO ternary composite was fabricated through a combination of liquid-phase precipitation and self-assembly. Structural, surface, and electrochemical studies revealed that the enhanced sensing performance originated from the synergistic integration of catalytic CuS, conductive Ti₃C₂, and rGO-assisted structural protection. Under optimized conditions, the sensor exhibited a fast response time of 3.7 s, a wide linear range of 0.01–10.35 mM, and a low detection limit of 3.33 µM (S/N = 3). In addition, satisfactory selectivity, stability, repeatability, and reproducibility were achieved. Recoveries of 98.1–105.0
The widespread use of the triazinone herbicide metribuzin (MTZ) demands reliable, rapid, and cost-effective analytical methods for environmental monitoring. In this work, we report, for the first time, the electroanalytical determination of MTZ based on its anodic behavior at a boron-doped diamond (BDD) electrode. The method exploits a differential pulse anodic stripping voltammetry (DPASV) approach, in which MTZ undergoes a preconcentration step via electrochemical reduction, followed by oxidation of the generated intermediate. The influence of surface pretreatment was systematically evaluated, demonstrating that cathodically pretreated BDD (BDD-CTP) significantly enhances electron-transfer kinetics and analytical sensitivity due to hydrogen-terminated surfaces characteristics. The electrochemical oxidation process was found to be irreversible, diffusion-controlled, and governed by a two-electron/two-proton mechanism, with a heterogeneous rate constant of 1.5 s‒1. Under optimized conditions (Eac = ‒0.60 V, tac = 60 s, pH 2.0), the method exhibited a linear response in the concentration range of 1.31 – 12.4 µmol L‒1 (R2 = 0.9994), with a limit of detection (LOD) of 0.17 µmol L‒1. The sensor demonstrated excellent repeatability (RSD ≤ 2.7
Chitosan-based coatings can be effectively used for tailoring degradation profiles of biomedical magnesium alloys. In this work, chitosan-phosphate coordinated coatings were for the first time deposited on WE43 magnesium alloy by the electrophoretic deposition approach. Scanning electron microscopy, X-ray photoelectron spectroscopy, atomic force microscopy, and Fourier-transform infrared spectroscopy were employed to characterize the surface morphology and composition of the coatings, along with dynamic and classical electrochemical impedance spectroscopy were used to evaluate initial stages of their degradation profiles in Hank’s solution. The results demonstrated that incorporation of small amounts of phosphate ions into the chitosan matrix significantly modified the morphology of the coatings and improved their short- and long-time corrosion resistance, with impedance values up 2.0–3.5 times higher than in the case of phosphate-free coatings. Phosphate ions also contributed to the formation of a thin conversion phosphate layer on the surface of Mg substrate during the deposition of the coatings, which also plays important role on corrosion resistance. Obtained results allowed to propose detailed deposition and corrosion mechanisms of the obtained coatings. Chitosan-phosphate coatings are electrophoretically deposited on WE43 Mg alloy; Intermodulation atomic force microscopy allowed to analyze local nanomechanical properties of coatings; Dynamic electrochemical impedance spectroscopy allowed to evaluate initial stages of degradation of chitosan-based coatings; Phosphate ions provide active protection of chitosan coatings; Mechanisms of chitosan-phosphate coatings deposition and corrosion degradations in Hank’s solution are proposed.
The electrodeposition of PbO2-TiO2 composite coatings from nitrate and methanesulfonate particle suspensions containing colloidal TiO2 particles and sodium dodecyl sulfate was systematically investigated. Attention was focused on the role of colloid-chemical properties of the suspensions in controlling PbO2 electrocrystallization, particle incorporation, and composite structure formation. Stable suspensions containing nanosized TiO2 particles ( 14 nm) were prepared by in situ hydrolysis of titanium(IV) isopropoxide. Adsorption studies demonstrated that both Pb2+ ions and the anionic surfactant adsorb specifically on TiO2 particles, altering their surface charge and aggregative stability. Addition of sodium dodecyl sulfate caused charge reversal of TiO2 particles and significantly affected electrophoretic transport and particle incorporation into the growing PbO2 matrix. Electrochemical investigations showed that colloidal TiO2 particles increase the rate of PbO2 electrodeposition in both kinetic and diffusion-controlled regions due to the formation of additional crystallization centers and the participation of adsorbed oxygen-containing intermediates on the TiO2 surface. A kinetic scheme describing PbO2 electrocrystallization at the electrode/suspension interface was proposed, extending the previously suggested colloid-electrochemical mechanism of composite electrodeposition. The composition, morphology, and phase structure of PbO2-TiO2 composites were found to depend strongly on electrolyte composition, dispersed phase concentration, current density, temperature, and hydrodynamic conditions. Incorporation of TiO2 particles leads to crystal refinement and significantly affects the α/β-phase ratio of PbO2. Methanesulfonate suspension electrolytes were shown to provide enhanced incorporation of TiO2 compared with nitrate systems while maintaining high aggregative stability. This work provides a systematic mechanistic analysis of the coupled influence of colloidal TiO2 particles and sodium dodecyl sulfate on PbO2 electrodeposition in nitrate and methanesulfonate electrolytes and proposes a generalized framework linking electrolyte composition, deposition kinetics, composite formation, and electrochemical performance.
Electrochemical CO2 conversion in high-temperature molten salts offers a promising route for coupling carbon utilization with the direct synthesis of value-added carbon nanotubes (CNTs). Molten salts provide high CO2 uptake, wide electrochemical windows, fast ion transport, continuous reaction conditions, and tunable electrolyte chemistry, which are favorable for controlled carbon formation. This review summarizes recent progress in CNT synthesis from CO2 electroreduction in molten carbonates and chloride-carbonate hybrid melts. The thermodynamic and kinetic basis of carbonate reduction is first discussed, including selectivity between carbon and CO formation, oxide-ion transport, and catalyst-related interfacial processes. The roles of anodes and cathodes are then examined, with emphasis on oxygen evolution, metal dissolution, catalyst supply, cathodic activation, CNT growth pathways, interfacial reconstruction, ion migration, redeposition, and electrode stability. These analyses indicate that CNT formation in molten salts is not a simple carbon electrodeposition process, but a dynamic interfacial growth process governed by electrolyte chemistry, electrode behavior, catalyst evolution, and mass transport. Separation and purification strategies are also reviewed. Finally, key challenges are highlighted, including unclear intermediates, insufficient understanding of CO2 absorption-electrolysis coupling, limited evaluation criteria, and the need for integrated reactor operation, product purification, and electrolyte recycling.
The goal of this work is to perform a thorough review of recent advancements in fabric based microfluidic fuel cells (FMFCs), as will be analytically followed. We will first engage in a very comprehensive presentation detailing the first and foremost importance of fabric materials, namely, by comparing polyester, cotton, and carbon fibers for porosity, wicking velocity, mechanical flexure, and resistance to chemicals. For anodes, the literature review summarizes biocompatible microbial and enzyme biocatalysts like Shewanella MR-1 and glucose dehydrogenase. More recent advancements in highly efficient carbon materials such as molybdenum carbide nanoparticles-modified carbonized cotton fabric (Mo2C/CCT) and lignin-derived electrospun carbon fibers are also incorporated, together with Nickel catalysts for urea oxidation reactions. Finally, for the cathode components of an FMFC, the literature review highlights the need for improved catalyst durability and the recent focus on identified cost-effective noble metal-free catalysts such as enzyme-based systems including bilirubin oxidase and bi-enzymes glucose oxidase-horseradish peroxidase systems. Advanced carbon-based materials, often doped with nitrogen or transition metals (e.g., Fe–N–C, Fe/Co-NC), are also proving effective for their catalytic activity and stability.
Gel polymer electrolytes containing small-area (SAGO) and large-area graphene oxide (LAGO) are modeled using a connectivity-driven framework to elucidate the influence of filler geometry on ion transport. While ionic conductivity of these systems has been reported previously, this work focuses on decoupling the effects of GO lateral size and filler loading on conductivity enhancement. The characteristic concentration (ϕc = t/L), where t is the GO sheet thickness and L is its lateral size, derived from GO sheet dimensions, defines the onset of connectivity, and normalized conductivity is analyzed as a function of reduced loading (ϕGO/ϕc). Model fitting reveals distinct scaling parameters for the two systems: SAGO shows a higher connectivity exponent (n = 0.34 ± 0.02) and moderate enhancement efficiency (B = 0.21 ± 0.02), indicating effective spatial coupling of hydrated ionic regions, whereas LAGO exhibits a lower exponent (n = 0.17 ± 0.16) and less uniform efficiency (B = 0.29 ± 0.14), reflecting weaker connectivity enhancement. These results highlight that GO lateral size controls the geometric onset of conductivity enhancement, while system-specific connectivity parameters capture distinct transport behavior. The model provides a predictive framework for designing gel polymer electrolytes with tailored ion-transport properties.
Serological testing complements nucleic acid-based assays by characterizing virus-associated humoral immune responses. However, conventional enzyme-linked immunosorbent assay (ELISA) workflows are laboratory dependent, and disposable electrochemical sensors must reconcile efficient charge transfer with stable biorecognition to support reliable serological analysis. Here, a screen-printed carbon electrode (SPCE) was modified with chitosan-functionalized nitrogen-doped graphene (N-Gr/CS) and electrodeposited gold nanoparticles (AuNPs) to construct an AuNPs/N-Gr/CS/SPCE platform for dual-mode determination of adenovirus-associated immunoglobulin G (AdV-IgG). Material and electrochemical characterization verified stepwise interface assembly and progressive enhancement of interfacial charge transfer. Scan-rate and kinetic analyses indicated adsorption-dominant redox behavior with a diffusion contribution. Under optimized conditions, the platform exhibited logarithmic concentration–response relationships in both electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). DPV achieved a linear range of 5 ng mL-1 to 1 mg mL-1 with a limit of detection of 3.45 ng mL-1, whereas the corresponding EIS values were 500 ng mL-1 to 8 mg mL-1 and 8.01 ng mL-1. The sensor demonstrated acceptable repeatability, inter-sensor reproducibility, and tolerance to the interferents tested. In 10-fold diluted healthy human plasma spiked with AdV-IgG, recoveries of 95.8-104.2
This study investigates the corrosion behaviour and defect characteristics of titanium modified through cathodic plasma electrolytic nitriding (cPEN), followed by post-annealing for bipolar plate applications in proton exchange membrane fuel cells (PEMFCs). The cPEN treatment and post-annealing reveal the formation of non-stoichiometric nitride and oxynitride phases. Potentiodynamic polarisation measurements show that cPEN-treated Ti (PEN Ti) exhibits the lowest corrosion current density (4.18 μAcm⁻2) and passive current density (45.08 μAcm⁻2) at 0.6 V under simulated PEMFC cathodic conditions compared to bare Ti, and annealed PEN Ti (A-PEN Ti). Electrochemical impedance spectroscopy at 0.6 V reveals enhanced corrosion resistance for the bare Ti. Mott–Schottky analysis reveals variations in defect distribution, with PEN Ti exhibiting a lower donor density compared to both bare and A-PEN Ti. Post-annealing enhances the long-term passivation behaviour of the cPEN-treated sample during potentiostatic polarisation. Bare Ti performs better in the PEMFC environment owing to its compact passive layer and its defect structure. Whereas nitriding and post-annealing alter its defect distribution, which affects the long-term corrosion performance. These findings emphasise the critical role of defect chemistry in tailoring corrosion performance in the PEMFC environment.
