Search Results (1,284)

The narrow operating temperature window of commercial V-W/TiO₂ catalysts severely limits NO_x removal efficiency, especially during low-load boiler operations. To achieve broad-temperature NO_x abatement, we developed Ce-M/Ti (M = Co, Fe, Mn, Mo) catalysts via a dual-site strategy. The temperatures required for 80% NO conversion (T₈₀) were 302 °C for Ce-Mo/Ti, 372 °C for Ce-Fe/Ti, 393 °C for Ce-Mn/Ti, and 415 °C for Ce-Co/Ti. Among them, Ce-Mo/Ti exhibited the most favorable low-temperature activity, outperforming a commercial catalyst (324 °C). Its turnover frequency (3.12 × 10⁻³ s⁻¹) was 1.29 times higher. Combined physicochemical characterization and density functional theory (DFT) calculations further reveal the mechanism behind the enhanced dual-site synergy in Ce-Mo/Ti. In the Ce-Co, Ce-Fe, and Ce-Mn sites, weak orbital hybridization leads to limited charge transfer. In contrast, Ce-Mo/Ti exhibits stronger hybridization between the Ce 4f/5d and Mo 4d orbitals, which breaks the inherent limitation of the Ce-based (Ce³⁺/Ce⁴⁺) redox capability and enables reverse electron transfer from Mo to Ce. This distinctive electron transfer direction creates a unique electronic environment, activating an efficient redox cycle between Mo⁶⁺/Mo⁵⁺ and Ce⁴⁺/Ce³⁺. This work offers a promising design strategy for dual-site catalysts with high NO_x removal efficiency over a wide temperature range. Full article

Density functional theory (DFT) calculations were employed to examine how carbon defects, symbiosis, and sulfur influence the wettability of coal pyrite by analyzing H₂O adsorption on distinct surface configurations. The comparison results of adsorption energy, Mulliken population, charge density, and electronic state density of water molecules on the surface of pyrite doped with carbon atoms show that the presence of carbon doping reduces the negative value of the adsorption energy of water molecules on the pyrite surface, the C atoms on the pyrite surface form weaker C-H bonds with the H atoms in the water molecules, the Fe-O bond strength weakens, and the thermodynamic trend weakens. And the bond of the pyrite surface with adsorbed carbon changes from an Fe-O bond to an Fe-C-O bond. The adsorption of water molecules on the pyrite surface is weakened, and there is a weaker thermodynamic trend. This is because the adsorption of carbon atoms changes from hydrophilic to nearly hydrophobic. The physical adsorption of sulfur atoms changes the adsorption energy of water molecules on the pyrite surface from negative to positive, and the bond changes from an Fe-O bond to an Fe-S-O bond, indicating that the adsorption intensity of water molecules on the pyrite surface with adsorbed sulfur is weakened, and there is no thermodynamic trend. The pyrite surface with adsorbed sulfur changes from hydrophilic to hydrophobic. Under the same impurity atom doping or adsorption concentration, the influence of sulfur on the adsorption of water molecules on the surface of pyrite is the greatest, followed by the adsorbed carbon, and the weakest is the carbon atom doping. Macroscopically, the overall hydrophobicity of the surface of coal-bearing pyrite covered with sulfur is greater than that of pyrite containing adsorbed carbon and even greater than that of coal-bearing pyrite doped with carbon atoms. Full article

To address the synergistic degradation mechanisms in engineering service environments, we propose a boron microalloying strategy to enhance the multifunctional surface performance of AlCoCrFeNiMo-based high-entropy alloys. AlCoCrFeNiMoTiBx coatings (x = 0, 0.5, 1, and 1.5) were fabricated on Q235 steel substrates using laser cladding. The microstructure of the coatings was characterized using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), while their wear and corrosion resistance were evaluated through tribological and electrochemical tests. The key findings indicate that boron addition preserves the original body-centered cubic (BCC) and σ phases in the coating while promoting the in situ formation of TiB₂, leading to lattice distortion. With increasing B content, the BCC phase becomes refined, and both the fraction and size of TiB₂ particles increase. Boron incorporation improves the coating’s microhardness and wear resistance, with the highest wear resistance achieved at x = 1, where abrasive and oxidative wear predominate. At lower content (x = 0.5), B enhances the stability of the passive film and thereby improves corrosion resistance. In contrast, excessive formation of large TiB₂ particles introduces defects into the passive film, accelerating its degradation. Full article

Soil samples from the urban area of Novi Sad were analyzed to determine the total concentrations of heavy metals including Cr, Pb, Cu, Zn, As, Mn, Ni, Co, Cd and Fe. In addition, leaching tests according to CEN 12457-2—Milli-Q deionized leaching procedure and ISO/TS 21268-2—CaCl₂ solution leaching procedure were conducted to assess the mobility of these metals. Multivariate statistical methods, including Pearson’s correlation, Principal Component Analysis (PCA) and Cluster Analysis, were applied to identify pollution sources and grouping patterns among elements. The results revealed a distinct clustering of Pb and Zn, separate from other metals, indicating their predominant origin from anthropogenic activities. Contamination Factor (CF), Pollution Load Index (PLI), and Geoaccumulation Index (Igeo) were calculated to evaluate the degree of pollution. Combining total concentration, mobility, and multivariate analyses offers a more comprehensive insight into the extent and origin of pollution in the urban area of Novi Sad. The results obtained are valuable for evaluating the soil conditions in the Western Balkans, which have been recognized as a necessity by the EU. Full article

Jets and outflows are key components of low-mass star formation, regulating accretion and shaping the surrounding molecular clouds. These flows, traced by molecular species at (sub)millimeter wavelengths (e.g., CO, SiO, SO, H₂CO, and CH₃OH) and by atomic, ionized, and molecular lines in the infrared (e.g., H₂, [Fe II], [S I]), originate from protostellar accretion disks deeply embedded within dusty envelopes. Jets play a crucial role in removing angular momentum from the disk, thereby enabling continued mass accretion, while directly preserving a record of the protostar’s outflow history and potentially providing indirect insights into its accretion history. Recent advances in high-resolution, high-sensitivity observations, particularly with the James Webb Space Telescope (JWST) in the infrared and the Atacama Large Millimeter/submillimeter Array (ALMA) at (sub)millimeter wavelengths, have revolutionized studies of protostellar jets and outflows. These instruments provide complementary views of warm, shock-excited gas and cold molecular component of the jet–outflow system. In this review, we discuss the current status of observational studies that reveal detailed structures, kinematics, and chemical compositions of protostellar jets and outflows. Recent analyses of mass-loss rates, velocities, rotation, molecular abundances, and magnetic fields provide critical insights into jet launching mechanisms, disk evolution, and the potential formation of binary systems and planets. The synergy of JWST’s infrared sensitivity and ALMA’s high-resolution imaging is advancing our understanding of jets and outflows. Future large-scale, high-resolution surveys with these facilities are expected to drive major breakthroughs in outflow research. Full article

Detailed description of phase composition and geochemistry of the Muschelkalk carbonate rocks of the Upper Silesian Province in Poland were presented in this article. The tests were carried out to determine mineralogical features and geochemical properties. The samples were collected from the formations of the Lower Muschelkalk (Gogolin Unit), Middle Muschelkalk (Diplopore Dolomite Unit) and Upper Muschelkalk (Tarnowice Unit, Boruszowice Unit). The following research methods were used: macroscopic description, X-Ray Diffraction, Fourier transform infrared spectroscopy, X-Ray Fluorescence and Atomic spectrometry with plasma intensification. The following carbonate phases were identified: a low-Mg calcite, a high-Mg calcite, a proto-dolomite, an ordered dolomite and a huntite. The results of XRD analysis allowed the determination of the chemical formulas of the mineral phases. XRF and ICP AES analyses allowed to establish the content of following trace elements: Sr, Ba, Al, Si, Fe, Mn, K, Na, S, Cl, Ti, Cr, Ni, Zn, Rb, Zr, Pb, As, V, Be, B, Co, Cu, Br, Mo and Cd. Apart from Sr and Ba, they are not fundamental components of carbonate rocks. They indicate the presence of minerals such as silicates, aluminosilicates, oxides and sulfides. Full article

Achieving selective, direct conversion of methane into value-added chemicals requires catalysts that can navigate the intrinsic trade-off between C–H bond activation and over-dehydrogenation. Transition metal phosphides (TMPs) have emerged as promising catalysts that can tune this selectivity. This work utilizes density functional theory (DFT) to systematically assess how the transition metal’s identity (M = Fe, Co, Ni) in isostructural M₂P phosphides governs this balance. The findings reveal that the high reactivity of Fe₂P and Co₂P, which facilitates initial methane activation, also promotes facile deep dehydrogenation pathways to coke precursors like CH*. In stark contrast, Ni₂P exhibits a moderated reactivity that kinetically hinders CH* formation while simultaneously exhibiting the lowest activation barrier for the C–C coupling of CH₂* intermediates to form ethylene. This revealed trade-off between the high reactivity of Fe/Co phosphides and the high selectivity of Ni₂P offers a guiding principle for the rational design of advanced bimetallic phosphides for efficient methane upgrading. Full article

Due to its efficiency, advanced oxidation processes (AOP), such as photo-Fenton, have become an alternative for removing emerging contaminants like paracetamol. The objective of this work was to perform a life cycle assessment (LCA) according to ISO 14040/44 for a heterogeneous photo-Fenton process catalyzed by Cu/Fe-pillared clays (PILC) for the removal of paracetamol from water. The study covered catalyst synthesis and four treatment scenarios, with inventories built from experimental data and ecoinvent datasets; treatment time was 120 min per functional unit. Environmental impacts for catalyst synthesis were quantified with ReCiPe 2016 (midpoint), while toxicity-related impacts of the degradation stage were assessed with USEtox™ (human carcinogenic toxicity, human non-carcinogenic toxicity, and freshwater ecotoxicity). Catalyst synthesis dominated most midpoint categories, the global warming potential for 1 g of Cu/Fe-PILC was 10.98 kg CO₂ eq. Toxicity results for S4 (photo-Fenton Cu/Fe PILC) showed very low values: 9.73 × 10⁻¹² CTUh for human carcinogenic and 1.29 × 10⁻¹³ CTUh for human non-carcinogenic. Freshwater ecotoxicity ranged from 5.70 × 10⁻⁴ PAF·m³·day at pH 2.7 (≥60 min) to 1.67 × 10⁻⁴ PAF·m³·day at pH 5.8 (120 min). Overall, optimizing pH and reaction time, are key levers to improve the environmental profile of AOP employing Cu/Fe-PILC catalysts. Full article

The karst landscape of Trenggalek Regency, located in several sub-districts including Dongko, Kampak, and Watulimo, is shaped by the Wonosari Formation and is characterized by springs and underground rivers. Due to water scarcity in the region, local communities heavily depend on these natural water sources. This study assesses the groundwater quality of 16 springs and 20 underground rivers to evaluate their suitability for consumption and associated health risks. Using the groundwater quality index (GWQI), human health risk assessment (HHRA), and statistical methods, various physicochemical parameters were analyzed, including pH, total dissolved solids (TDS), electrical conductivity (EC), and concentrations of iron (Fe²⁺), manganese (Mn²⁺), calcium carbonate (CaCO₃), and sulfate (SO₄). Water generally meets the World Health Organization standards for safe drinking. However, correlation analysis reveals notable mineral dissolution and possible anthropogenic influence. TDS strongly correlates with EC (r = 0.97), while Fe²⁺ shows significant relationships with Mn and TDS. Conversely, CaCO₃ shows a negative correlation with EC and TDS, suggesting alternative sources beyond rock weathering. The HHRA indicates higher non-carcinogenic health risks from Fe²⁺ contamination in underground rivers compared to springs. The study’s novelty comes in its integrated assessment of groundwater quality and health hazards in Trenggalek’s karst region, which uses GWQI, HHRA, and statistical analysis to show geochemical interactions and highlight iron-related health issues in underground rivers. Full article

The aim of this study is to determine the spatial distribution of geochemical anomalies of selected potential toxic elements in the soils of the river basins in the Northeastern Caucasus—specifically the Ulluchay, Sulak, and Sunzha Rivers. A concentration of 25 chemical elements was measured using inductively coupled plasma mass spectrometry (ICP-MS). Petrogenic elements commonly found in the Earth’s crust (Al, Na, Ca, Fe, Mg) showed high concentrations (Na up to 306,600.70 mg/kg). Conversely, concentrations of Ag, Cd, Sn, Sb, and Te at many sampling sites were extremely low, falling below the detection limits of analytical instruments. The geochemical indicators Cf (contamination factor) and Igeo (geoaccumulation index) indicate that the regional characteristics of the territory, such as lithological conditions, hydrochemical schedules, and the history of geological development of the territory, affect the concentration of elements. Anomalous concentrations were found for seven elements (Ba, Na, Zn, Ag, Li, Sc, As), whereas no anomalies were identified for Be, Mg, Al, Mn, Fe, Co, Ni, Cu, Pb, Te, and Cs. For the most part (8 of 10), the sampling sites with anomalous chemical element content are located in the basin of the Sunzha River. Two sites with anomalous chemical element content have been identified in the Sulak River Basin. Anomalous values in the Sulak River Basin are noted for two chemical elements—Ba and Na. Natural features such as geological structure, parent rock composition, vertical climatic zonation, and landscape diversity play a major role in forming geochemical anomalies. The role of anthropogenic factors increases in localized areas near settlements, industrial facilities, and roads. The spatial distribution of geochemical anomalies must be considered in agricultural management, the use of water sources for drinking supply, the development of tourist routes, and comprehensive spatial planning. Full article

Hydrogen has been explored as a greener alternative for greenhouse gas emissions reduction. Sodium borohydride (NaBH₄) is a favorable hydrogen carrier due to its high hydrogen content, safe handling, and rapid hydrogen release. This work presents a novel synthesis of the catalyst CoFe₂O₄/Fe₂O₃ using nanocellulose fibers (TCNF) as reactive templates for metal adsorption and subsequent calcination. The resulting material was tested for H₂ production from basic NaBH₄ aqueous solutions (10–55 °C). The catalyst’s composition is 74.8 wt% CoFe₂O₄, 25 wt% Fe₂O₃, and 0.2 wt% Fe₂(SO₄)₃ with agglomerated spheroidal particles (15–20 nm) and homogeneous Fe and Co distribution. The catalyst produced 1785 mL of H₂ in 15 min at 25 °C (50 mg catalyst, 4.0% NaBH₄, and 2.5 wt% NaOH), close to the stoichiometric maximum (2086 mL). The maximum H₂ generation rate (HGR) reached 3.55 L min⁻¹ g_cat⁻¹ at 40 °C. Activation energies were determined using empirical (38.4 ± 5.3 kJ mol⁻¹) and Langmuir–Hinshelwood (L–H) models (42.2 ± 5.8 kJ mol⁻¹), consistent with values for other Co-ferrite catalysts. Kinetic data fitted better to the L–H model, suggesting that boron complex adsorption precedes H₂ evolution. Full article

Three variants of high-entropy alloys (HEAs) from the AlCoCuFeNi group, containing different amounts of Al and Cu, were developed and produced via induction melting and casting into ceramic moulds. The ingots were homogenized at 1000 °C for 10 h. Analyses revealed that variations in Al and Cu concentrations led to significant changes in the material’s microstructure, hardness, strength, and impact strength. In the equiatomic variant, differential scanning calorimetry revealed a peak associated with the phase transformation, indicating that this alloy’s microstructure consists of two distinct phases. In contrast, when the concentrations of Al and Cu are reduced, a single-phase microstructure is observed. The equiatomic variant (used as a reference) is characterized by its hardness and brittleness, exhibiting slight ductility, with a tensile strength of 80 MPa, a hardness of 400 HV5, and an impact strength of 1.9 J/cm². However, with adjusted Al contents of 1/2 and Cu contents of 1/4, the alloy displays exceptional strength combined with good plasticity, achieving a tensile strength of up to 450 MPa with 60% elongation, and an impact strength of 215 J/cm². The non-equiatomic variants exhibit a comparatively more straightforward microstructure and enhanced ductility, which may facilitate easier processing of these alloys. Fractography investigation revealed a ductile mode of fracture in the samples. Full article

In this work, a novel solid polymer electrolyte with a disordered structure has been designed, combining polyethylene glycol (PEG) as the flexible segments and hexamethylene diisocyanate (HDI) as the rigid segments. The synthesis was realized by alternating flexible PEG with rigid HDI through a peptide bond (–CO–NH–), which disrupts the ordered structures of PEG, generating electron-deficient Lewis acid groups. The pathbreaking introduction of HDI blocks not only bridges links between the PEG molecules but also generates electron-deficient Lewis acid groups. Therefore, the original ordered structures of PEG are disrupted by both the alternating chains between PEG and HDI and the Lewis acid groups. As a result, the PEG_H/L4000 electrolytes (PEG molecular weight of 4000) exhibit a strong anion-capture ability that decreases the crystallinity of polymers, which further achieves a high ionic conductivity close to 10⁻³ S·cm⁻¹ with the lithium-ion transference numbers up to 0.88. The symmetric Li|PEG_H/L4000|Li cells maintain a low and stable voltage polarization for more than 800 h at 0.1 mA·cm⁻². Furthermore, the LiFePO₄|PEG_H/L4000|Li all-solid-state cells perform well both in cycling and rate performances. The design of polymer disordered structures for polymer electrolytes provides a new thought for manufacturing all-solid-state lithium-ion batteries with high safety as well as long life. Full article

Cobalt-doped iron disulfide (FeS₂) thin films were synthesized via chemical bath deposition (CBD) followed by annealing at 450 °C, yielding phase-pure pyrite structures with multifunctional properties. A deposition temperature of 95 °C is critical for promoting Co incorporation, suppressing sulphur vacancies, and achieving structural stabilization of the film. After annealing, the dendritic morphologies transformed into compact quasi-spherical nanoparticles (~100 nm), which enhanced the crystallinity and optoelectronic performance of the films. The films exhibited strong absorption (>50%) in the visible and near-infrared regions and tunable direct bandgaps (1.14 to 0.96 eV, within the optimal range for single-junction solar cells. Electrical characterization revealed a fourth-order increase in conductivity after annealing (up to 4.78 Ω⁻¹ cm⁻¹) and confirmed stable p-type behavior associated with Co²⁺-induced acceptor states and defect passivation. These results demonstrate that CBD enabled the fabrication of Co-doped FeS₂ thin films with synergistic structural, electrical, and optical properties. The integration of earth-abundant elements and tunable electronic properties makes these films promising absorber materials for the next-generation photovoltaic devices. Full article

This study aims to determine the optimal Mo content for corrosion resistance in two alloys, FeCoCrNiMo_x and Fe_0.5CoCrNiMo_x. The alloys were fabricated using laser powder bed fusion (LPBF) technology with varying Mo contents (x = 0, 0.05, 0.1, 0.15). The corrosion behavior of these alloys was investigated in 3.5 wt.% NaCl solution at room temperature and 60 °C using electrochemical testing and X-ray photoelectron spectroscopy (XPS). The results show that all alloys exhibit good corrosion resistance at room temperature. However, at 60 °C, both alloys without Mo addition exhibit severe corrosion, while the Fe_0.5CoCrNiMo_0.1 alloy demonstrates the best corrosion resistance while maintaining the highest strength. The enhanced corrosion resistance is attributed to the optimal molybdenum addition, which refines the passive film structure and promotes the formation of Cr₂O₃. Furthermore, molybdenum oxide exists as MoO₄²⁻ ions on the surface of the passive film, significantly improving the alloy’s corrosion resistance in chloride-containing environments. Full article