Search Results (2,092)

Porous highly cross-linked polymer (PIP) was synthesized by a polycondensation reaction between hexachlorocyclotriphosphazene and piperazine. The obtained polymer has a surface area of 76.9 m²/g and a mesoporous structure. After carbonization, the obtained product (PIP-C) has a surface area of 177 m²/g. The obtained carbon product contained nitrogen and phosphorus heteroatoms, which leads to a higher specific capacitance (155.6 F/g) and catalytical activity in the electroreduction of oxygen (15.9 A/g). This work shows the possibility of the use of such porous phosphazene polymers as precursors for heteroatom-doped carbon materials, which might be used in electrochemical devices like electrodes for supercapacitors or metal-free electrocatalysts in fuel cells. Full article

The development of efficient and durable oxygen evolution reaction (OER) catalysts from earth-abundant materials is essential for advancing alkaline water electrolysis. Herein, nanograss-like CoMn₂O₄ electrode films are directly grown on stainless-steel substrates via a temperature-controlled hydrothermal approach, and their OER performance is systematically investigated. The CoMn₂O₄ obtained at 120 °C (CMO-120) delivers the best catalytic activity in 1.0 M KOH, requiring an overpotential of 292 mV at 10 mA cm⁻², which is lower than those synthesized at 150 (CMO-150) and 90 °C (CMO-90). Notably, activity of CMO-120 becomes even more pronounced at elevated current densities, achieving the low overpotential of 434 mV even at 300 mA cm⁻², substantially outperforming both CMO-90 and CMO-150 electrodes. The enhanced activity is attributed to an interconnected nanograss architecture with mixed Co²⁺/Co³⁺ and Mn²⁺/Mn³⁺ redox couples and abundant defect-related oxygen species, which result in increased electrochemically active surface area and improved charge transportation throughout the nanograss architecture that facilitate OH⁻ adsorption and OER intermediate transformation. Furthermore, CMO-120 demonstrates excellent durability (100 h) after electro-oxidation-induced surface activation. These findings highlight precise temperature regulation as an effective strategy for optimizing Mn-Co spinel for efficient alkaline OER applications. Full article

Dopamine (DA) is a critical catecholaminergic neurotransmitter that facilitates signal transduction across synaptic junctions and modulates essential neurophysiological processes, including motor coordination, motivational drive, and reward-motivated behaviors. The fabrication of cost-effective, miniaturized, and high-fidelity analytical platforms is imperative for real-time DA monitoring. Due to its inherent electrochemical activity, carbon-based amperometric sensors constitute the primary modality for DA quantification. In this study, graphite, multi-walled carbon nanotubes (MWCNTs), and graphene were immobilized within an ethyl 2-cyanoacrylate (ECA) polymer matrix. ECA was selected for its rapid polymerization kinetics and established biocompatibility in electrochemical frameworks. All fabricated composites demonstrated robust electrocatalytic activity toward DA; however, MWCNT- and graphene-based sensors exhibited superior analytical performance, characterized by highly competitive limits of detection (LOD) and quantification (LOQ). Specifically, MWCNT-modified electrodes achieved an interesting LOD of 0.030 ± 0.001 µM and an LOQ of 0.101 ± 0.008 µM. Discrepancies in baseline current amplitudes suggest that the spatial orientation of carbonaceous nanomaterials within the cyanoacrylate matrix significantly influences the electrochemical surface area and resulting baseline characteristics. The impact of interfering species commonly found in biological environments on the sensors’ response was systematically evaluated. The best-performing sensor, the graphene-based one, was used to measure the DA intracellular content of PC12 cells. Full article

Halide perovskites have many advantages in environmental remediation. The photocatalytic performance of halide perovskites is often hindered by low specific surface area and rapid photogenerated carrier recombination. The aim of this work is to prepare a green, novel photocatalyst in the form of biochar-anchored Cs₃Bi₂Br₉ perovskite composites. The rose-petal-derived biomass carbon (RC) provides adsorption sites and high electrical conductivity, while the perovskite Cs₃Bi₂Br₉ can efficiently capture visible right and degrade pollutants, and the reciprocal effect can enhance the photocatalytic efficiency of the composite. The results of scanning electron microscopy (SEM) showed the Cs₃Bi₂Br₉ particles were loaded on the surface of RC. Compared with bare Cs₃Bi₂Br₉, Cs₃Bi₂Br₉/RC composite has a more perfect structure, higher specific surface area, enhanced ability to absorb visible light, and reduced bandgap value. As visible-light-driven photocatalysts, the prepared Cs₃Bi₂Br₉/RC composites can enhance the removal efficiency of Rhodamine B. The Cs₃Bi₂Br₉/RC–0.2 composite displays the highest degradation efficiencies for RhB (10 mg/L), reaching 98% within 60 min. And the rate constant (k) is 1.9 times that of bare Cs₃Bi₂Br₉. The results of electrochemical impedance spectroscopy (EIS) show that the interaction between RC and Cs₃Bi₂Br₉ speeds up charge carrier separation and transfer. During photocatalytic process, holes (h⁺) and superoxide radicals (·O₂⁻) played major roles. The composites also showed excellent stability. It is meaningful to deal with a large number of withered rose petals to make them high-value products. This work not only provides a guideline for the construction of perovskite composites materials but also shows the promising prospects of biochar composites in deep treatment for contaminated water. Full article

Landfill leachate (LL) is a complex wastewater characterized by high concentrations of organic matter and heavy metals, posing significant challenges to conventional treatment technologies. Electrochemical methods, particularly electrocoagulation (ECG), have shown promise for LL treatment; however, issues related to operational optimization and electrode durability remain insufficiently addressed. In this study, a novel electrocoagulation-based approach is proposed that systematically integrates process optimization with an explicit assessment of iron electrode reusability, which is an aspect that has been rarely explored in previous ECG studies on LL. Key operational parameters—current density, pH, inter-electrode distance, electrode surface area, and electrode material—were optimized to enhance treatment performance. Optimal conditions were achieved using iron electrodes at a current density of 256 A/m², pH 8, an inter-electrode distance of 1 cm, and an effective electrode surface area of 19.5 cm²/L. Under these conditions, removal efficiencies of 100% for zinc, 94.9% for copper, and 54.5% for total organic carbon (TOC) were obtained, demonstrating effective simultaneous removal of inorganic and organic contaminants. The electrode reusability tests showed stable removal efficiencies over ten consecutive operational cycles, highlighting the potential for reduced operational costs and improved process sustainability. Additionally, the treated effluent exhibited reduced phytotoxicity, as evidenced by lower germination inhibition (GI), reduced root growth inhibition (RGI), and enhanced removal of humic substances. Overall, the results demonstrate that the proposed ECG approach is a robust, flexible, and environmentally sustainable solution for LL treatment, with clear advantages over conventional EC systems in terms of long-term performance and resource efficiency. Full article

Chlorinated solvents such as vinyl chloride (VC) and trichloroethylene (TCE) represent a persistent threat to groundwater-derived drinking-water supplies, including riverbank filtration well fields in alluvial aquifers. This work presents a laboratory-scale evaluation of an electrochemical barrier concept for targeted VC and TCE removal performed using synthetic groundwater representative of a riverbank filtration setting in the Danube River basin. Experiments were conducted in a covered batch reactor equipped with Ti/IrO₂–RuO₂ mixed-metal-oxide anodes and Ti cathodes, systematically varying current intensity (10–60 mA), treatment time (0–60 min), active anode surface area (12–48 cm²), and inter-electrode distance (0.5–2.5 cm). At 60 mA, VC and TCE removals of 97% and 95%, respectively, were achieved within 20 min, while prolonged treatment to 60 min increased removal to about 99% for VC and 98.5% for TCE. Multivariate analysis (PCA) and correlation assessment identified applied current as the dominant control parameter, particularly for TCE removal, whereas electrode configuration and spacing played secondary roles within the investigated range. For the most cost-effective treatments meeting Serbian drinking-water criteria, estimated electricity costs were 0.39 €/m³ for VC and 0.10 €/m³ for TCE. Overall, the results demonstrate the technical feasibility and promising cost-effectiveness of electrochemical barriers as a proactive measure to protect riverbank filtration systems from future VC and TCE contamination n urban environments, while highlighting the need for follow-up studies on by-product formation and long-term performance. Full article

Polyaniline (PANI), characterized by its proton-coupled redox mechanism and multicolor reversibility, is widely investigated for adaptive optical interfaces. Compared to inorganic oxides, PANI offers advantages in cost-effectiveness, mechanical flexibility, and molecular tunability; however, its practical implementation faces challenges related to kinetic limitations and environmental instability. This review presents a comprehensive analysis of PANI-based electrochromic materials, examining the intrinsic correlations among synthesis methodologies, microstructural characteristics, and optoelectronic performance. Synthesis strategies, including chemical oxidative polymerization, electrochemical deposition, and template-assisted techniques, are evaluated. Emphasis is placed on resolving the trade-off between optical contrast and switching kinetics by constructing high-surface-area porous nanostructures and inducing chain ordering via functional dopants to shorten ion diffusion paths and reduce charge transfer resistance. Fundamental electrochromic properties are subsequently discussed, with specific attention to degradation mechanisms triggered by environmental factors, such as pH drift, and stabilization strategies involving electrolyte engineering and composite design. Furthermore, the review addresses the evolution of applications from single-band monochromatic displays to dual-band smart windows for decoupled visible/near-infrared regulation and multifunctional integrated systems, including electrochromic supercapacitors and adaptive thermal management textiles. Finally, technical challenges regarding long-term durability, neutral color development, and large-area manufacturing are summarized to outline future research directions for PANI-based optical systems. Full article

Electrolyte degradation and trace water contamination critically affect the lifetime and safety of lithium-ion batteries. In organic-based electrolytes such as acetonitrile (MeCN), even small amounts of water can trigger ${\mathrm{PF}}_6^{-}$ hydrolysis, producing HF, POF₃, and related species that contribute to electrolyte ageing and alter interfacial reactions. This study explores the electrochemical signatures of ageing and moisture contamination in Bu₄NPF₆- and LiPF₆-based MeCN electrolytes through a systematic cyclic voltammetry protocol. Platinum electrodes with different surface morphologies—flat, Nafion-coated, and nanostructured—were compared to assess their sensitivity to water-induced degradation. Cathodic Faradaic currents appearing around −0.7 to −1.0 V vs. Ag/AgCl were attributed to the protonic species generated by ${\mathrm{PF}}_6^{-}$-induced hydrolysis. The presence of LiPF₆, commonly used in battery electrolytes, further increases the concentration of anions responsible for the protonic species, therefore contributing to the acceleration of the electrolyte degradation. Experiments using a Nafion proton-conductive membrane assess the protonic origin of these peaks. Meanwhile, nanostructured platinum exhibits approximately four times higher current responses and enhanced sensitivity to water additions, reflecting the influence of surface roughness and active area. Overall, the findings indicate that electrode morphology significantly influences the detectability of ageing- and water-driven reactions, supporting the potential of nanostructured Pt as a diagnostic material for in situ monitoring. Full article

Hydrogen, as an alternative energy carrier, presents significant prospects for the transition to more environmentally friendly energy solutions. However, its efficient and safe storage remains a challenge, as materials with high adsorbent capacity and long-term storage capability are required. This study focuses on the synthesis and characterization of a composite material comprising carbon fiber and manganese dioxide (MnO₂/CFs), for the purpose of hydrogen storage. Carbon fiber was chosen as the basis for the composition of the composite material due to its large active surface area and its excellent mechanical, thermal, and electrochemical properties. The deposition of MnO₂ on the surface of carbon fibers took place through two different synthetic pathways: electrochemical deposition and chemical synthesis under different conditions. The electrochemical method enabled the production of a greater amount of oxide with optimized structural and chemical properties, whereas the chemical method was simpler but required more time to achieve comparable or lower-capacity performance. Elemental analysis of the electrochemically produced composites showcased an average of 40.5 ± 0.05 wt% Mn presence, which is an indicator of the quantity of MnO₂ on the surface responsible for hydrogen storage, while the chemically produced composites showcased an average of 7.6 ± 0.05 wt% Mn presence. Manganese oxide’s high specific capacity and reversible redox reaction participation make it suitable for hydrogen storage applications. The obtained results of the hydrogenated samples through physicochemical characterization indicated the formation of the MnOOH intermediate. Regarding these findings it may be remarked that carbon fiber/MnO₂ composites are promising candidates for hydrogen storage technologies. Finally, the fabricated carbon fiber/MnO₂ composites were applied successfully as working electrodes for analysis of the [Fe(CN)₆]^3−/4− redox system in aqueous KCl solutions. Full article

In this study, a novel Bi₂O₃/BiOBr_0.9I_0.1 (BO0.9−BBI0.1) composite photocatalyst was successfully synthesized via a single-pot solvothermal method for the efficient degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under visible light. The structure, morphology, and optical properties of the photocatalyst were characterized through X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra (DRS), Steady-state photoluminescence (PL), and Electrochemical Impedance Spectroscopy (EIS). The composite exhibits a 3D hierarchical morphology with increased specific surface area and optimized pore structure, enhancing pollutant adsorption and providing more active sites. Under visible light irradiation, BO0.9−BBI0.1 achieved a 92.4% removal rate of 2,4-D within 2 h, with a reaction rate constant 5.3 and 4.6 times higher than that of pure BiOBr and BiOI, respectively. Mechanism studies confirm that photogenerated holes (h⁺) and superoxide radicals (·O₂⁻) are the primary active species, and the Z-scheme charge transfer pathway significantly promotes the separation of electron-hole pairs while maintaining strong redox capacity. The catalyst also demonstrated good stability over multiple cycles. This work provides a feasible dual-modification strategy for designing efficient bismuth-based photocatalysts for pesticide wastewater treatment. Full article

Nanoporous gold (np-Au) has attracted significant attention for biomedical and electrochemical applications due to its high surface area, tunable morphology, and excellent biocompatibility. In this study, polycrystalline gold surfaces were modified by anodization in 0.3–0.9 M oxalic acid to produce np-Au layers. The influence of anodization conditions on surface morphology, chemical composition, electronic properties, and corrosion resistance in artificial saliva was systematically investigated. Surface morphology and porosity were analyzed by scanning electron microscopy combined with image analysis, revealing a transition from fine and uniform porosity to highly developed but structurally heterogeneous nanoporous structures with increasing oxalic acid concentration. Energy-dispersive spectroscopy confirmed surface oxidation and adsorption of oxygen- and carbon-containing species after anodization, while gold remained the dominant component. Scanning Kelvin probe measurements demonstrated significant modifications of surface electronic properties, including changes in contact potential difference, governed by nanostructure geometry and surface chemistry. Electrochemical tests in artificial saliva showed that increasing nanoporousness led to reduced thermodynamic stability, with the sample anodized in 0.3 M oxalic acid providing the most favorable balance between corrosion resistance and surface activity. These results demonstrate that oxalic acid anodization is a simple and effective approach for tailoring gold surfaces for biomedical applications, particularly in dentistry. Full article

In this study, the service behavior of an X65 oil and gas pipeline in seawater and production water environments was simulated by a corrosion experiment, and the influence of surface treatment (polishing and scratching) on its corrosion behavior was systematically analyzed. The corrosion resistance of the material was evaluated by means of scanning electron microscopy (SEM), an electrochemical test, and uniform corrosion rate calculations. The results show that the corrosion degree of X65 steel in an oilfield production water environment is significantly higher than that in a seawater environment. The uniform corrosion rate of the welding area is as high as 1.05 mm/y, which is more sensitive than that of the matrix material. The surface treatment has a significant effect on the corrosion behavior. The polishing treatment reduces the corrosion current density of the matrix material from 472.44 μA/cm² to 313.10 μA/cm², and the polarization resistance increases to 14.07 kΩ·cm², which effectively improves its corrosion resistance. The scratch treatment significantly reduces the corrosion resistance of the material, and the corrosion current density of the welding area at the scratch site is as high as 313.00 μA/cm², even more than that of the untreated matrix material. The study further points out that the scratches and welding areas generated during the pipeline cleaning process will significantly aggravate the tendency of local corrosion and pitting corrosion due to their microstructure heterogeneity. This study provides a clear theoretical basis and engineering guidance for the anti-corrosion design and maintenance of offshore oil and gas pipelines in complex water quality environments. Full article

Pesticides have been widely applied in agricultural practices over the past decades to protect crops from pests and other harmful organisms. However, their extensive use results in the contamination of soil, water, and agricultural products, posing significant risks to human and environmental health. Exposure to pesticides can lead to skin irritation, respiratory disorders, and various chronic health problems. Moreover, pesticides frequently enter surface water bodies such as rivers and lakes through agricultural runoff and leaching processes. Therefore, developing effective analytical methods for the rapid and sensitive detection of pesticides in food and water is of great importance. Electrochemical sensing techniques have shown remarkable progress in pesticide analysis due to their high sensitivity, simplicity, and potential for on-site monitoring. Two-dimensional (2D) carbon nanomaterials have emerged as efficient electrocatalysts for the precise and selective detection of pesticides, owing to their large surface area, excellent electrical conductivity, and unique structural features. In this review, we summarize recent advancements in the electrochemical detection of pesticides using 2D carbon-based materials. Comprehensive information on electrode fabrication, sensing mechanisms, analytical performance—including sensing range and limit of detection—and the versatility of 2D carbon composites for pesticide detection is provided. Challenges and future perspectives in developing highly sensitive and selective electrochemical sensing platforms are also discussed, highlighting their potential for simultaneous pesticide monitoring in food and environmental samples. Carbon-based electrochemical sensors have been the subject of many investigations, but their practical application in actual environmental and food samples is still restricted because of matrix effects, operational instability, and repeatability issues. In order to close the gap between laboratory research and real-world applications, this review critically examines sensor performance in real-sample conditions and offers innovative approaches for in situ pesticide monitoring. Full article

Sluggish oxygen reduction reaction (ORR) remains a critical barrier to advancing intermediate-temperature electrochemical energy devices. Here, we demonstrate that strain engineering in two platforms, epitaxial thin films and freestanding membranes, systematically tunes ORR kinetics in Ruddlesden-Popper LaSrCoO₄. In epitaxial films, film thickness is varied to control in-plane tensile strain, whereas in freestanding membranes strain relaxation during the release step using water-soluble sacrificial layers produces flat or wrinkled architectures. Electrochemical impedance spectroscopy analysis reveals more than an order of magnitude increase in the oxygen surface exchange coefficient for tensile-strained films relative to relaxed films, together with a larger oxygen vacancy concentration. Wrinkled freestanding membranes provide a further increase in oxygen surface exchange kinetics and a lower activation energy, which are attributed to increased active surface area and local strain variation. These results identify epitaxial tensile strain and controlled wrinkling as practical design parameters for optimizing ORR activity in Ruddlesden-Popper oxides. Full article

This study examined cast AZ31 magnesium alloy and its variant containing micro-alloying elements of Y and Ca (AZXW alloy), evaluating their potential as anode materials in magnesium–air batteries. The AZXW alloy was fabricated via two manufacturing techniques: casting and extrusion. The synergistic influence of Y and Ca, in conjunction with the production procedure, on the microstructure, electrochemical characteristics, and anodic discharge behavior of the examined alloys was investigated. The addition of Y and Ca results in the formation of secondary phases that affect grain size, particle size, and distribution, as well as the electrochemical performance and discharge properties of the Mg–air battery constructed for this study, over 24 h or until fully discharged. This work demonstrates the potential to enhance discharge performance and electrochemical behavior by adjusting the aqueous electrolyte solution in the battery through the incorporation of Citric Acid (C.A) at varying concentrations. The incorporation of citric acid into the aqueous electrolyte improves battery stability and specific energy as long as citric acid is present in the solution. Magnesium hydroxide (Mg(OH)₂) begins to form on the anode surface as its concentration progressively decreases due to complexation with dissolved magnesium ions. This diminishes the effective anode area over time, ultimately resulting in the distinctive “knee-type” collapse characteristic of electrolytes containing citric acid. Full article