Search Results (1,144)

To address the capacity decay of NCM811 caused by microcracks and cation disorder during cycling, La, Al, and F tri-doped micron-sized single-crystal NCM811 material with a LiNbO₃ coating was synthesized via a facile co-solvent method. Using a mixed glucose–urea thermal solution as the reaction medium, metal salts were incorporated, followed by step-wise sintering, ball-milling, heat treatment, and wet-chemical coating. This approach enables atomic-level precursor mixing and ensures homogeneous element distribution. La³⁺ enlarges the lithium layer spacing to enhance ion diffusion and Al³⁺ suppresses Ni³⁺ reduction to Ni²⁺, mitigating cation mixing and improving conductivity, while F⁻ stabilizes the crystal structure via its strong electronegativity. The LiNbO₃ coating protects the interface from electrolyte attack, and the single-crystal morphology effectively suppresses microcracking. Compared to unmodified single-crystal NCM811 prepared identically, the modified material exhibits reduced cation disorder, improved crystallinity, and superior thermal stability. Electrochemical tests in half-cells with 1 M LiPF₆/(EC/EMC/DMC) electrolyte (2.8–4.3 V) show an initial discharge capacity of 208.32 mAh/g at 0.1 C and 194.05 mAh/g at 1 C. After 200 cycles at 1 C, the capacity retention remains at 92.21%, exceeding the market average. Rate performance is also notably enhanced, with the 5 C discharge capacity increasing from 141.12 mAh/g (unmodified) to 166.81 mAh/g, demonstrating improved kinetics and structural stability. Full article

Photosynthetic algae–microbial fuel cells (PAMFCs) are attractive for energy-positive wastewater treatment and carbon mitigation. However, PAMFC performance under continuous flow is often constrained by limited cathodic electron-acceptor supply and unstable photosynthetic biofilms, while the extent to which cathode interfacial engineering can stabilize diurnal power output and assimilative NH₄⁺–N removal remains unclear. In this study, the sponge-like and petal-like ZnO_0.2-NiO@rGO-modified carbon fibers (ZnO_0.2-NiO@rGO-pCFs and ZnO_0.2-NiO@rGO-pCFp) and pre-fabricated carbon felt (pCF) were used as cathode materials to construct three sets of PAMFC systems. Under light–dark cycling, the engineered cathodes reached steady operation within about 6.5 d and increased the steady-state voltage to approximately 0.35 V, compared with approximately 0.08 V for pCF. Under continuous-flow conditions, cathodic NH₄⁺–N removal exhibited a stable diurnal rhythm, with higher removal during illumination at about 43–51% than in the dark at about 29–30%, consistent with algal assimilation as the primary nitrogen sink, while cathode modification mainly improved the cathodic microenvironment and response stability. Compared with pCF, the ZnO_0.2–NiO@rGO cathode enriched a more even, Chlorophyta-dominated algal biofilm with an approximate relative abundance of 80%, indicating that its selective interfacial environment favors biofilm stabilization and sustains in situ oxygen production and cathodic electron-acceptor supply. Consequently, the composite cathode enhanced voltage output and stabilized light-enhanced, assimilative NH₄⁺–N removal under aeration-free operation, while establishing an interpretable link between electrochemical performance and 18S rDNA-derived community assembly features, thereby providing a low-cost cathode design basis for nitrogen removal in wastewater treatment. Full article

Salophen-type Schiff base ligands derived from salicylaldehyde and naphthalene aldehydes were synthesized and coordinated to Ni(II) to obtain three nickel complexes (NiL1–NiL3), which were evaluated as heterogeneous electrocatalysts for the methanol electro-oxidation reaction (MOR) in alkaline media. The ligands and complexes were fully characterized by FT-IR, ¹H NMR, EPR, DART-MS, and elemental analysis, confirming tetradentate coordination through imine nitrogen and phenoxide oxygen donors. Electrochemical studies were carried out using carbon paste electrodes modified with 15 wt % of each complex. Cyclic voltammetry revealed that the electrocatalytic activity is mediated by the Ni(II)/Ni(III) redox couple, with Ni(III) oxohydroxide species acting as the active sites for methanol oxidation. Among the evaluated systems, NiL1@CPE showed superior performance at low methanol concentrations, while NiL2@CPE and NiL3@CPE exhibited higher current densities at elevated methanol concentrations. Scan-rate studies indicated that the oxidation process is diffusion-controlled, and a linear response to methanol concentration was observed over a wide concentration range. The results demonstrate that ligand structure and coordination geometry play a crucial role in modulating the electrocatalytic behavior of Ni(II) Schiff base complexes, highlighting their potential as cost-effective molecular catalysts for alkaline methanol oxidation. Full article

The chlorophyll molecule is considered a low-cost material, easy to synthesize, and easily extracted from plant leaves. It exhibits high chemical stability, structural flexibility, and high absorbance ability at the visible range of electromagnetic radiation. In this work, the geometrical, electronic, and optical properties of pure, dissolved, and doped chlorophyll (C1) natural organic dye were computed by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The solvents considered include water (H₂O), acetone (C₂H₆O), dichloromethane (CH₂Cl₂), chloroform (CH₃Cl), and dimethyl-sulfoxide (DMSO) (C₂H₆OS). The solar photovoltaic parameters, such as light-harvesting efficiency (LHE), oscillation strength (f), free energy of electron injection (${\Delta \mathrm{G}}_{\mathrm{I}\mathrm{n}\mathrm{j}.}$) and regeneration (${\Delta \mathrm{G}}_{\mathrm{R}\mathrm{e}\mathrm{g}.}$), open-circuit voltaic (V_OC), and efficiency ($\eta$), were also investigated. The evaluated energy gap slightly shifted from 1.920 eV to 1.980 eV based on the solvent polarity, while the UV-Visible absorption spectrum red-shifted from 422.3 nm to 439.8 nm, improving the overall efficiency up to 21.5% in DMSO solvent. The (LHE) and (${\Delta \mathrm{G}}_{\mathrm{I}\mathrm{n}\mathrm{j}.}$) properties regarding Cl molecules improved up to 69.1% and −1.384 eV when dissolved in chloroform and DMSO solvents, respectively. Doping C1 molecule via metal transition atoms such as zinc (Zn), nickel (Ni) and copper (Cu) further modified the optical and photovoltaic performance. Doped C1 molecule via Cu atom shows the best photonic results, including the highest open-circuit voltage (V_oc) and conversion efficiency ($\mathrm{Ƞ}$), while the Ni-doped C1 dye displays the longest lifetime, 1.699 µs, and the highest electronic coupling constant, 1.975 eV; thus, it has the superior photovoltaic performance. These results demonstrate that both solvents and transition metal atom modification significantly improve C1 performance, making metal-doped C1 a promising low-cost and eco-friendly sensitizer for dye-sensitized solar cells (DSSCs). Full article

Laser processing has been widely investigated as an effective approach for improving surface properties and consolidating advanced materials, particularly complex alloys such as titanium aluminides (TiAl). In this study, laser surface remelting was applied to binary (Ti-45Al) and ternary (Ti-45Al-2Co and Ti-45Al-2Ni) alloys produced by powder metallurgy via blended elemental (BE) and pre-alloyed (PA) powder routes. Laser powers of 50 and 100 W were employed, resulting in a high-energy-density surface remelting regime applied to both green compacts and sintered samples with relatively high initial porosity, under an argon-controlled atmosphere. Microstructural and phase analyses were performed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), while mechanical behavior was assessed by instrumented microindentation. Laser processing promoted the formation of a dense and homogeneous surface layer, approximately 150 μm thick, accompanied by significant microstructural refinement and enhanced hardness and elastic modulus. While rapid solidification led to crack formation in laser-treated sintered samples, the green compacts exhibited defect-free modified layers. Overall, the results demonstrate that laser surface remelting is an effective strategy for enhancing the surface integrity and mechanical performance of TiAl alloys processed by powder metallurgy. Full article

The pursuit of high-energy-density cathode materials has positioned LiNiO₂ as a promising candidate due to its high theoretical capacity. However, its practical application is hindered by structural instability, cation mixing, and sluggish Li-ion mobility. This study presents a strategic co-doping approach to enhance the electrochemical performance of R3m-structured LiNiO₂ by introducing Na at the Li site and Nb/Al/W at the Ni site. First-principles calculations based on density functional theory (DFT), combined with the bond valence sum energy (BVSE) method, were employed to evaluate the structural, electronic, and transport properties of the doped systems. The optimized lattice parameters reveal that co-doping induces lattice expansion and suppresses cation disorder, thereby improving structural integrity. Formation energy validates the thermodynamics of the modified structures. Furthermore, BVSE-based ion migration mapping shows that Na/Nb and Na/Al co-doping significantly broadens Li-ion diffusion pathways and lowers migration barriers compared to pristine LiNiO₂. These results demonstrate that dual-site doping is an effective strategy to overcome intrinsic limitations of Ni-rich layered oxides, offering a rational design route cathode for next-generation Li-ion battery. Full article

Modern materials science is focused on the development of steels with a range of performance characteristics, including high strength, wear resistance, corrosion resistance, and long-term performance in various conditions. Special attention is paid to the control of the microstructure of steels at the crystallization stage, which allows for the improvement of metal properties without significantly increasing the cost of the manufacturing process. One of the promising methods of microstructural engineering is the modification of steels with dispersed particles of refractory compounds, such as titanium carbide (TiC), zirconium carbide (ZrC), and tungsten carbide (WC). However, the processes of dissolution, dissociation, and interaction of such ceramic particles with the metal melt, as well as their influence on the formation of the microstructure and properties under the conditions of non-equilibrium crystallization, which is typical for centrifugal casting, are not sufficiently studied for austenitic stainless steels. In this work, the influence of dispersed carbide particles of TiC, ZrC, and WC, which are introduced into the melt of austenitic stainless steel (Cr ≈ 18%, Ni ≈ 10%) during centrifugal casting, on the redistribution of alloying elements, the formation of the microstructure, and the mechanical properties of the material is investigated. Special attention is paid to the kinetic nature of the dissolution and interaction of the carbides with the melt, as well as the directional distribution of elements across the cross-section of the billets. The study includes the analysis of the distribution of Ti, W, and Zr across the cross-section of the centrifugally cast billets, the study of the microstructure and phase composition of the inclusions using SEM/EDS, and mechanical testing. It is found that the implementation of dispersion hardening leads to an increase in the tensile strength by up to ~22% compared to the initial alloy (from 496 to 612 MPa), while the impact strength decreases by 5–25% (from 110 to 82 J/cm²) depending on the type and quantity of the introduced particles. The analysis of microhardness shows the presence of a gradient of local properties across the cross-section of the centrifugally cast billets, with microhardness values ranging from ~110 to 195 HV0.5. For the modified samples, the relative difference between the inner and outer zones is ~5–20%, reflecting the combined effect of non-equilibrium solidification, redistribution of alloying elements, formation and spatial distribution of secondary phases, and local structural heterogeneity. These results confirm the possibility of controlling the distribution of properties within a single billet. Full article

In this work, an A-site deficient perovskite, (La_0.3Sr_0.6Ce_0.1)_0.9Co_0.1Ti_0.9O_3−δ (LSCCoT) was applied as an additional catalytic layer on Ni–YSZ anode for biogas-fuelled SOFC. Under reducing conditions, the formation of well-dispersed, socketed Co nanoparticles was observed due to the cobalt exsolution from the perovskite lattice. The structural and microstructural characterization confirmed phase stability of the perovskite after high-temperature reduction in hydrogen and the presence of exsolved nanoparticles on the grains’ surface. Electrical conductivity measurements showed thermally activated semiconducting behavior in air (E_a = 0.582 ± 0.121 eV) and a strongly enhanced conductivity with weak temperature dependence in hydrogen (E_a = 0.057 ± 0.001 eV). Single-cell tests performed under a CH₄/CO₂ (60/40 vol%) biogas mixture revealed a 30% increase in maximum power density at 800 °C compared to the reference cell. During 100 h of operation, the modified cell exhibited reduced performance degradation, improved internal reforming activity, and a more stable outlet gas composition. Full article

Hydrogels have attracted significant interest in multifunctional applications. Among them, self-healing hydrogel stands out for its ability to autonomously repair damage through reversible interactions, yet achieving both rapid self-healing and superior mechanical strength remains challenging. In this study, we report the fabrication of a dual cross-linked hydrogel (PAA-Alg-B) prepared via free radical polymerization of acrylic acid and alginic acid, employing N,N′-methylenebisacrylamide, or vinyl-modified nanocellulose as primary cross-linker, with Fe³⁺ or borax serving as an additional dynamic cross-linker. The resulting borax based hydrogel (PAA-Alg-B) exhibits remarkable fast self-healing efficiency enabled by reversible borate ester bonds and hydrogen bonding. It demonstrates tunable mechanical strength with toughness of 137 kJ/m³ and elongation at break up to 1117%, alongside exceptional swelling capacity (448 g/g). The adsorption studies reveal high removal efficiencies for heavy metals, with maximum capacities of 87.57 mg/g (Cr³⁺), 114.02 mg/g (Ni²⁺), and 99.42 mg/g (Cu²⁺), governed by chemisorption kinetics. The PAA-Alg-B can also be used as a promising solid-state electrolyte and separator for flexible supercapacitors. Protonic modulation via H₂SO₄ soaking significantly enhances ionic conductivity, electrochemical performance, and cycling stability. These findings highlight the potential of natural polymer-based, mechanically robust, self-healing hydrogels for sustainable wastewater treatment and advanced energy storage applications. Full article

Ciprofloxacin (CIP) is an antibiotic that is widely used in humans and animals. However, the compound has been detected in animal-derived products and the environment due to its extensive use, causing serious concern for public health and environmental safety. The issue raises the urgent need to develop innovative techniques to monitor CIP. Therefore, this study aims to develop a simple and sensitive CIP sensor called the boron-doped diamond nanoparticle-modified screen-printed electrode (BDD NPs/SPE) and the nickel oxide nanoparticle-modified BDD NPs/SPE (NiO NPs/BDD NPs/SPE). NiO NPs were synthesized via green synthesis using Spatholobus littoralis Hassk. root extract as the reducing agent. The formation and characteristics of NiO NPs were then confirmed through a UV-Vis spectrophotometer, XRD, PSA, FT-IR, and XPS. The successful modification of SPE was confirmed through SEM-EDX, followed by measurements using square-wave voltammetry. The results showed that the modified SPE could detect CIP over a concentration range of 0.1–100 µM and produced a low detection limit of 0.109 µM for BDD NPs/SPE and 0.054 µM for NiO NPs/BDD NPs/SPE. The proposed method was successfully applied to the determination of CIP in commercial tablets, milk, and human urine, with a satisfactory % recovery from 95 to 100%. The current study successfully developed a simple yet highly sensitive sensor that enabled robust, reliable, and efficient detection of CIP, showing its strong potential for practical applications. Full article

The increasing environmental pollution with persistent organic compounds demands the development of sustainable materials capable, among others, of simultaneous adsorption and catalytic degradation of pollutants. In this study, nickel-modified biocarbons were obtained in the process of biomass pyrolysis at the temperatures of 500 and 800 °C, with the Ni content of 5 and 10% by weight, in order to determine the effect of synthesis conditions on the structure, surface chemistry and functional properties of materials. A wide range of research methods was used to analyze structural parameters, elemental composition, surface morphology, functional groups as well as adsorption and photocatalytic properties. The results indicate that the pyrolysis temperature is the main factor determining the evolution of biocarbons, leading to a decrease in the specific surface area and microporosity, an increase in carbon aromatization, a reduction in oxygen groups, and an increase in alkalinity and thermal stability. The addition of nickel promotes formation of crystalline Ni phases and redox centers, while partially blocking micropores. As a result, the materials obtained at 800 °C are characterized by an increased photocatalytic activity. The paper provides mechanistic insights into the structure–property–function relationships and practical guidance for the design of biocarbons with optimized adsorption and photocatalytic properties. Full article

The purpose of this study was to assess the suitability of tubular polymeric ultrafiltration membranes for use in a closed-loop water system within a rubber manufacturing plant. This research focused on determining the transport and separation properties of polymeric tubular membranes during the ultrafiltration of wastewater generated from washing vulcanised rubber hoses. The tests were conducted using the installation of the UF-1 membrane supplied by APEKO Sp. z o.o. This study evaluated the performance of modified PES membranes with a molecular weight cut-off (MWCO) of 4 kDa and PVDF membranes with MWCO of 100 kDa in the wastewater treatment process, as well as the effectiveness of membrane regeneration. Given the characteristics of wastewater, the key parameters for evaluating ultrafiltration performance included the determination of contaminant separation coefficients (R, %) for non-ionic surfactants (NIS) and chemical oxygen demand (COD), as well as turbidity reduction. The results demonstrated that the tested membranes substantially improved the visual quality of the wastewater by reducing turbidity by more than 95% and exhibited high separation efficiency for the analysed contaminants, with initial values of R_NIS = 95% and R_COD = 85% at the beginning of the ultrafiltration cycle, decreasing to R_NIS < 10% and R_COD < 10% after several hours of operation. During closed-loop filtration, when a twentyfold concentration of contaminants in the retentate was reached, membrane fouling occurred, significantly reducing filtration performance. Chemical cleaning enabled the recovery of approximately 70% of the initial performance for modified PES membranes and 60% for PVDF membranes. Full article

The Tunca River is a transboundary watercourse between Türkiye and Bulgaria. It is the longest tributary of the Meriç River System (MRS) and joins the Meriç River in Türkiye after flowing through Bulgarian territory. In this study, the concentrations of Potentially Toxic Elements (PTEs), including As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, and Zn, as well as lead (Pb) isotope compositions, in sediments from the Turkish section of the Tunca River were investigated. Contamination levels and ecological risk status were evaluated using single and integrated indices and Sediment Quality Guidelines (SQGs). According to the Geoaccumulation Index (I_geo), Enrichment Factor (EF), and Contamination Factor (Cf) values, As, Cd, Mn, and Pb exhibit moderate to considerable levels of contamination. Pollution Load Index (PLI) and Modified Degree of Contamination (mCdeg) values indicate that pollution from total metal loads locally reaches moderate to high levels. PTE concentrations were below Threshold Effect Concentration (TEC) values, suggesting a low probability of adverse biological effects. However, the Potential Ecological Risk Index (PERI) values indicate locally moderate to high ecological risk of total metal loads. Geostatistical analyses suggest that Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn are of geogenic origin, whereas As, Sb, and Mn are associated with anthropogenic sources. The ²⁰⁶Pb/²⁰⁷Pb ratios in the sediments range from 1.18 to 1.25, while the ²⁰⁸Pb/²⁰⁶Pb ratios vary between 2.07 and 2.22. These values deviate slightly from natural isotopic signatures, suggesting anthropogenic influence on Pb concentrations. Full article

Maize silage can play a key role in policies aimed at stabilising local energy systems, as it constitutes a critical renewable feedstock for European biogas plants. By providing a dense and predictable source of chemical energy, it supports balance and reliability in the agricultural energy sector. To convert this potential into stable energy production, operators require kinetic models that translate routine silage quality indicators into concrete guidance for digester operation and control. Therefore, the aim of this article was to evaluate the batch kinetics of anaerobic digestion (AD) of maize silage and to select an adequate model for describing biochemical methane potential (BMP) profiles and associated energy recovery in the context of start-up, organic loading rate (OLR), hydraulic retention time (HRT) and feedstock preparation. Ten batches of silage (A–J) were examined, covering a realistic range of pH, electrical conductivity (EC), dry and volatile solids, ash, protein–fat–fibre fractions, fibre composition (NDF, ADF and ADL), derived fractions (hemicellulose, cellulose, and residual organic matter (OM)), C/N ratio and macro-/micronutrient profiles, including trace elements relevant to methanogenesis (Ni, Co, Mo, and Se). BMP tests were carried out in batch mode, and the resulting curves were fitted using the modified Gompertz and a first-order kinetic model. Methane yields of approx. 100–120 m³ CH₄/Mg fresh matter (FM) and 336–402 m³ CH₄/Mg volatile solids (VS), with CH₄ contents of 52–57% v/v, were typical for energy-grade maize silage. Kinetic and energetic behaviours were governed mainly by residual OM and hemicellulose (shortening the lag phase and increasing the maximum methane production rate), the ADL/cellulose ratio (controlling the slower hydrolytic tail), EC and Na/Cl/S (extending the lag phase), and C/N together with Ni/Co/Mo/Se (stabilising methanogenesis). The modified Gompertz model reproduced BMP curves with a pronounced lag phase and asymmetry more accurately (lower error and better information criterion values), and its parameters directly support start-up design, OLR ramp-up and energetic performance optimisation in bioenergy reactors. The novelty of this work lies in combining batch BMP tests, comparative kinetic modelling and detailed silage characterisation to establish quantitative links between kinetic parameters and routine maize silage quality indicators that are directly relevant for biogas plant operation and renewable energy production. Full article

In this work, a rational catalyst design based on interfacial architecture engineering is proposed for low-temperature dry methane reforming (DMR) at 550 °C. Ni-based catalysts containing 10 wt% Ni were developed on a γ-Al₂O₃ support modified with 9 wt% MgO–1 wt% ZrO₂. Zirconia promoters were introduced either by dry impregnation or via an ammonia vapor-assisted route to construct a Ni–NiO–ZrO₂ interfacial network. The effects of ZrO₂ content (0, 1, and 3 wt%) and synthesis route on metal–support interactions, oxygen mobility, and coke resistance were systematically investigated. ZrO₂ promotion increased the fraction of reducible Ni species and preferentially enhanced CO₂ activation, thereby promoting the reverse water–gas shift (RWGS) reaction and lowering the H₂/CO ratio. In contrast, ammonia vapor-assisted preparation induced the formation of an LDH-derived Ni–NiO–ZrO₂ surface network, which increased the concentration of surface-accessible Ni species, suppressed excessive zirconia coverage, and significantly improved apparent oxygen mobility. These synergistic structural features are consistent with enhanced oxygen-assisted carbon removal and improved coke management through regulation of the nature of carbon species, leading to more balanced activation of CH₄ and CO₂. Overall, this study provides insights into interfacial structure–performance relationships for designing efficient Ni-based catalysts for CO₂ utilization. Full article