Search Results (1,657)

In this paper we investigate the use of sucrose as a reducing agent for the carbothermal reduction in spent ternary cathode materials. During this process, lithium from the cathode material is converted into water-soluble Li₂CO₃, while the high-valent transition metals are reduced to insoluble metallic elements and oxides. The influence of various pyrolysis temperatures, sucrose dosages, and pyrolysis times on the reduction degree of high-valent metals. Furthermore, the influence of leaching conditions on lithium recovery efficiency is examined. Under the optimal conditions of a pyrolysis temperature of 650 °C, a sucrose dosage of 15 wt.%, a pyrolysis time of 30 min, a leaching solid–liquid ratio of 30 g/L, and a leaching time of 30 min, the lithium leaching rate reaches 97.9%. Characterization via XRD, XPS and SEM reveals that sucrose serves as an effective carbothermal reducing agent. It facilitates the reduction of high-valent transition metals to insoluble metallic elements and oxides while simultaneously enabling the recovery of lithium as Li₂CO₃. Consequently, this method achieves an efficient separation of lithium from other metallic elements. Compared to traditional recycling processes, it avoids the low lithium recovery rates often associated with subsequent separation steps. Full article

High-frequency immersed plasma discharge represents an efficient method for the generation of reactive oxygen and nitrogen species (RONS) in liquid media, leading to complex redox and oxidative processes in biologically relevant systems. Although plasma-generated reactive species in liquids have been widely investigated, it remains insufficiently understood how working-gas-dependent plasma chemistry translates into oxidative outcomes in iron-containing model systems, where plasma-derived species may interact with transition-metal redox cycling. The novelty of this study lies in the combined assessment of gas-dependent RONS accumulation, deoxyribose oxidative degradation, and plasma-induced changes in Fe(II) availability using a high-frequency immersed plasma discharge. Herein, we examined whether treatment with high-frequency immersed discharge influences the redox state of iron in a working gas-dependent manner, thereby affecting oxidative degradation in the deoxyribose model. Plasma treatment was performed under air and argon working gas conditions, and oxidative degradation was evaluated using the thiobarbituric acid reactive substances (TBA-RS) assay. In parallel, the concentrations of long-lived reactive species, including hydrogen peroxide, nitrites, and nitrates, were determined spectrophotometrically. The results demonstrated a treatment-time-dependent increase in oxidative degradation and reactive species accumulation, with more pronounced oxidative effects observed under argon plasma conditions. In the presence of ferrous ions, plasma treatment resulted in a gas-dependent effect, characterized by a synergistic enhancement of oxidative degradation under argon and a biphasic effect under air. Most notably, in Fe(II)-containing samples, 10 min of argon plasma treatment increased TBA-RS formation to approximately 2.7-fold of the Fe(II) control, whereas air plasma produced a biphasic response, with an initial decrease followed by an approximately 40% increase at the longest exposure time. Additional experiments suggest that plasma may influence the redox state and availability of ferrous ions, thereby affecting their participation in Fenton-type reactions and radical-mediated processes. The findings suggest that the overall oxidative outcome in plasma-treated systems is governed not only by the concentration of plasma-generated reactive species but also by plasma-induced modifications of transition metal redox chemistry. These preliminary results on the combined roles of plasma-generated reactive species and transition-metal chemistry contribute to understanding plasma–liquid interactions in such systems. Full article

The quest for sustainable hydrogen production via water electrolysis requires the development of efficient, non-precious-metal electrocatalysts. This work presents the sonochemical-assisted synthesis of cobalt ferrite (CoFe₂O₄) nanoparticles as a sustainable alternative to noble metal catalysts. Nanoparticles were synthesized by varying the ultrasonic tip power (40%, 50%, and 60%) to investigate the this effect on their structural and electrochemical properties. Comprehensive characterization using X-ray diffraction, Mössbauer spectroscopy, and transmission electron microscopy confirmed the formation of phase-pure nanoscale spinel structures, with crystallite size increasing from 11.28 to 21.79 nm as the sonication power increased. Electrochemical analysis revealed that the sample synthesized at 60% power (CoFe₂O₄-60) exhibited the highest electrocatalytic performance among the synthesized samples for both the hydrogen and oxygen evolution reactions (HER and OER) in alkaline media. This superior performance is attributed to its largest electrochemically active surface area (ECSA = 6.95 cm²) and lowest overpotentials (${\eta }_{10}=-360$ mV for HER and 410 mV for OER). Despite the larger crystallite size, high-power sonication induced higher density of surface defects and roughness, as evidenced by Mössbauer spectroscopy and electrochemical capacitance measurements. Furthermore, all samples exhibited excellent operational stability during 120 h of chronopotentiometric testing. Moreover, the efficiency of the electrolizer for water splitting was calculated to be 64.7%. These findings demonstrate that ultrasonic power tuning can influence the structural and electrochemical properties of CoFe₂O₄ nanoparticles, contributing to improving durability and bifunctional efficient electrocatalytic activity for alkaline water electrolysis. Full article

This study presents the production of isoamyl, n-butyl and cyclohexyl esters of levulinic acid with an excellent yield under solvent-free conditions. The catalysts used were MgAlO and M²⁺MgAlO-mixed oxides containing the transition metals (M²⁺ = Co²⁺, Ni²⁺, Zn²⁺), obtained from calcined layered double hydroxides (LDH). They are easily accessible, low-cost, and environmentally friendly and possess the requisite acid–base properties for esterification reactions. The effect of reaction time and the molar ratio of levulinic acid to the alcohols used on the esterification reaction was investigated. The catalysts were characterized by X-ray diffraction (XRD), XRF, SEM and temperature-programmed desorption of CO₂ (TPD-CO₂). Gas chromatography–mass spectroscopy (GC/MS) was used for the identification and quantification of the product mixtures. Mixed oxides containing transition metals exhibited significantly higher activity than MgAlO. Under the selected reaction conditions, the conversion of levulinic acid and the yield of isoamyl ester reached 100% at a reagent ratio of 1:1. As a by-product of esterification, only dicyclohexyl ether was found at a reactant ratio of 1:1.5. Full article

The transition metal copper (Cu) is an essential trace element for humans and serves as a cofactor for numerous enzymes. Therefore, intracellular Cu homeostasis must be tightly regulated. Meanwhile, Cu is increasingly used in industrial and biomedical applications, particularly in nanoparticle (NP) form. However, studies have demonstrated that Cu(II) oxide (CuO) NPs are highly toxic. Therefore, understanding the underlying toxic effects of such compounds is of the utmost importance. In this context, transcriptomic profiling is regarded as a valuable tool. Nevertheless, comparative studies addressing organ-relevant models, such as the liver and lungs, are scarce. Furthermore, no transcriptomic studies have been conducted on human bronchial lung epithelial cells exposed to CuO NPs and Cu²⁺. In this study, we compared the cellular effects of human bronchial lung epithelial cells exposed to both CuO NPs and Cu²⁺ to the effects in human liver cells exposed to Cu²⁺ by applying RNA sequencing. Although cytotoxicity was comparable, we showed that Cu uptake was highly dependent on both the cell type and the form of Cu. The most pronounced concentration-dependent transcriptional changes were observed with CuO NP exposure in BEAS-2B cells. The only differentially expressed genes (DEGs) found by all exposures and treatments were metallothioneins (MTs). The most sensitive targets of Cu-induced toxicity were related to nuclear factor erythroid 2-related factor 2 (NRF2), nuclear factor kappa-light-chain-enhancer of activated B cells (NFkB), and mitogen-activated protein kinase (MAPK) signaling. Furthermore, the effects observed at the transcriptome level were studied at the functional level, such as cell cycle regulation and cytokine release. Thus, we demonstrated that the two cell types differ in susceptibility, and that complementing transcriptome profiling with functional studies provides important mechanistic insights. Full article

This study investigates the integration of nanofiltration (NF) and membrane distillation (MD) for the selective separation and recovery of critical metals from effluents generated by supercritical water oxidation (SCWO) of lithium-ion batteries. Beyond resource recovery, the proposed hybrid system addresses the urgent environmental challenge associated with highly contaminated battery recycling effluents, which pose severe risks to aquatic ecosystems if improperly managed. NF90 and NF270 membranes exhibited complementary behavior: NF90 achieved high rejection of Co, Ni, and Mn (>70%) with a minimum lithium rejection of 30%, whereas NF270 showed lower rejection of divalent metals (40%) and lower lithium rejection (<20% at pH = 7), along with a higher permeability. Subsequent MD enabled water recovery while concentrating lithium in the MD concentrate (brine), maintaining near-complete rejection of transition metals (>90%) and reducing the effluent conductivity by more than 85%. Surface characterization (SEM–EDS, AFM, BET, and contact angle) revealed fouling mechanisms and wettability loss, highlighting operational stability limitations. In this hybrid approach, nanofiltration enables the selective separation of lithium from transition metals, while membrane distillation promotes water recovery and concentrates lithium into a recoverable brine, with fouling and wetting defining the operational boundaries of the process. Overall, the results demonstrate that coupling SCWO with NF–MD represents a viable and scalable pathway for simultaneous effluent detoxification and lithium recovery, contributing to circular economy strategies and the sustainable management of battery-recycling wastewater. Full article

Understanding the atomic-scale ionic motion and transport in layered transition-metal oxides is essential for elucidating structural stability and electronic behaviour in complex systems. Here, we investigate nanoscale Na dynamics in Na₁RuO₃ and Na_1.5RuO₃ using room-temperature ab initiomolecular dynamics at the r²SCAN + U level. While Na mobility plays a key role in local coordination, its nanoscale mechanism remains nuanced and unexplored. Our simulations show that Na ions undergo pervasive rattling, with Na_1.5RuO₃ enabling exploration of larger volumes and exhibiting incipient migration compared to the more confined behaviour in Na₁RuO₃. In addition, oxygen’s contribution to redox capacity decreases from $43\%$ to $24\%$ with increasing Na content. These nanoscale insights demonstrate that tuning the local ionic environment governs charge compensation and dynamical response in ruthenate frameworks, with direct implications for the design of Na-ion battery cathodes. Full article

High-entropy oxide (HEO) thin films hold significant potential for applications in spintronics and catalysis; however, their widespread utilization is hindered by weak room-temperature ferromagnetism (RTFM). Herein, we demonstrate a facile vacuum annealing strategy to enhance the RTFM of HEO thin films. (FeNiAlCrMn)O films exhibit a saturation magnetization (M_S) of 5.9 emu/cm³ and a Curie temperature (T_C) of 350 K after vacuum annealing at 1173 K. Mechanistic investigations reveal that the enhanced RTFM originates from an annealing-induced phase transition from rocksalt-to-spinel. Structurally, annealing facilitates cation diffusion from octahedral to tetrahedral sites, forming a highly crystalline, long-range magnetic lattice of spinel ferrite. Electronically, tetrahedral occupation shortens M–O bonds, drives electron transfer toward metal cations, and enhances orbital hybridization, thereby strengthening magnetic exchange coupling. This study provides a simple and effective strategy for tailoring the RTFM of HEO thin films. Full article

O3-type layered transition-metal oxides are widely regarded as promising cathode materials for sodium-ion batteries due to their intrinsically high sodium content and favorable energy density. Nevertheless, their practical rate capability is hindered by sluggish Na⁺ transport and relatively high diffusion barriers. To address this issue, elemental substitution has emerged as an effective modification strategy. In this work, fluorine (F), characterized by strong electronegativity and a small ionic radius, is introduced to partially substitute oxygen in the bulk lattice of O3-type NaNi_1/3Fe_1/3Mn_1/3O₂ (NNFM). First-principles calculations demonstrate that F incorporation leads to an expansion of the interlayer spacing along the c-axis and a weakening of Na–O interactions, both of which facilitate Na⁺ migration. Among the considered configurations, Mn-adjacent substitution exhibits the lowest formation energy, indicating enhanced thermodynamic stability. Furthermore, electronic structure analysis reveals a reduced band gap (from 0.515 eV to 0.342–0.356 eV) and strengthened O-2p/Mn-3d orbital hybridization, contributing to improved electronic conductivity. These findings provide atomistic insights into F-induced modulation mechanisms and suggest an effective pathway for optimizing Na⁺ transport in O3-type cathodes. Full article

Oxygen stoichiometry critically governs the phase stability and physical properties of transition-metal oxides, yet a unified understanding of how oxygen-stoichiometry-driven phase reconstruction underlies the cooperative evolution of multiple physical properties in SrCoO_x remains lacking. Here, high-quality epitaxial brown millerite SrCoO_2.5 and perovskite SrCoO_3−δ thin films were grown by pulsed laser deposition under controlled oxygen conditions. Their structural, magnetic, electrical, optical, and photocatalytic properties were systematically compared. SrCoO_2.5 exhibits antiferromagnetic insulating behavior, infrared-dominant transmittance, and higher photocatalytic activity, whereas SrCoO_3−δ shows ferromagnetism, much lower resistivity, and strong optical opacity. First-principles calculations reveal that oxygen-stoichiometry-driven phase reconstruction strongly modifies the electronic structure, accounting for the distinct magnetic, transport, and optical responses. These results establish a direct correlation between oxygen stoichiometry, structural transformation, and multifunctional properties in SrCoO_x, highlighting oxygen-vacancy ordering as an effective route to tailoring correlated oxide functionalities. Full article

High-nickel layered oxide cathodes, exemplified by LiNi_0.9Co_0.05Mn_0.05O₂ (NCM90), exhibit high specific capacity but suffer from severe interfacial degradation and structural instability during electrochemical cycling. Herein, we present a phosphate-based in situ modification approach that forms a durable, self-established cathode–electrolyte interphase (CEI), thereby resolving these key challenges from the root. We employ a controlled (NH₄)₂HPO₄ coating and optimized thermal treatment to fabricate a thin, dense layer of crystalline lithium phosphate on the NCM90 surface. This coherent layer serves as an artificial CEI precursor, which electrochemically evolves into a highly stable and ionically conductive interfacial shield during operation. It effectively suppresses parasitic reactions, mitigates transition metal dissolution, and alleviates mechanical strain induced by phase transitions. Comprehensive optimization of calcination temperature and coating content identifies 760 °C and 1 wt% as the optimal conditions, yielding a well-preserved layered structure and effectively suppressed Li⁺/Ni²⁺ mixing compared with the pristine NCM90. When tested at 0.1 C in the potential range of 2.75–4.3 V, the coated electrode delivers a high initial discharge specific capacity of 204.08 mAh g⁻¹. After 100 charge–discharge cycles at 1 C, it retains 89.24% of its capacity, and its rate capability is also significantly improved. Collectively, these findings verify that forming a customized CEI via precursor coating successfully suppresses interfacial degradation and improves structural integrity, thus representing a viable, scalable pathway toward advanced lithium-ion batteries with exceptionally stable cathodes. Full article

The demand for high-performance energy storage systems with enhanced energy and power density is growing alongside the renewable energy, mobile devices, and electric vehicle sectors. MXenes, a class of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides, have emerged as promising electrode materials for next-generation energy storage systems owing to their high electrical conductivity, hydrophilicity, and tunable surface chemistry. This review provides a comprehensive analysis of recent progress in MXene-based energy storage systems, focusing on MXene synthesis routes, their performance in energy storage applications, associated challenges, and future research directions. It discusses the advantages and disadvantages of various MXene synthesis routes and MXene-based composites, defect engineering, and MXene oxidation, which are crucial for energy storage applications, including rechargeable batteries and supercapacitors. The review also explores the challenges and prospects of scaling up MXenes and their composites for energy storage applications and the existing obstacles to integrating these materials into energy storage systems, with the aim of developing next-generation energy storage systems. Full article

The production of green hydrogen via aqueous electrolysis of hydrogen sulfide (H₂S) holds significant potential to address challenges related to sustainable energy generation and environmental protection. The electrocatalytic splitting of water polluted with highly toxic H₂S is attractive for industrial applications because the process: (i) is less power-consuming than direct thermal H₂S decomposition; (ii) achieves high Faradaic efficiencies for hydrogen production; and (iii) yields elemental sulfur as an added-value by-product. This review covers a brief discussion on sulfide-containing water sources and electrochemical methods for hydrogen production from H₂S, specifically Direct, Indirect, and Electrochemical Membrane Reactor (EMR) systems. To become commercially and economically attractive, these approaches require improvements in electrolysis efficiency through the development of low-cost electrode materials that are resistant to sulfur poisoning and corrosion, while possessing high catalytic activity, enhanced stability, and durability. Early research focused on carbon-based materials combined with noble metal oxides, transition metal compounds, and related materials. Since their practical performance is limited, investigations have shifted toward nanostructured electrocatalysts with unique crystal structures and designs, which show significantly improved efficiency for H₂S electrolysis. This review highlights the potential of H₂S electrolysis for hydrogen production, giving special attention to recent advancements in electrode materials. Full article

Developing sustainable and fire-resistant infrastructure is a critical technological, economic, and environmental challenge for modern construction stakeholders. Traditional cementitious composites experience severe microstructural degradation under extreme temperatures and their high carbon footprint exacerbates global environmental concerns. While the individual high-temperature behaviors of supplementary cementitious materials and fibers have been widely studied, the long-term synergistic mechanisms of high-volume fly ash combined with steel fibers under extreme thermal shock remain critically underinvestigated. To address this urgent need and bridge this scientific gap, hybrid mortars incorporating high-volume fly ash (FA) and steel fibers (SF) were tested under prolonged curing (150 days) and extreme heat (up to 600 °C). In terms of engineering and construction effects, the optimal CFA50-F hybrid composite delivered the highest residual compressive and flexural capacities (retaining nearly 60% of its late-age compressive strength at 32.00 MPa), preserved acoustic continuity (restricting UPV loss to 41.4%), and severely restricted high-temperature capillary permeability (limiting the water absorption increase to 49.7%) compared to traditional plain matrices. Scientifically, this superior resistance is governed by a two-step protective mechanism. High-volume FA chemically stabilizes the matrix by consuming vulnerable portlandite and preventing the formation of expansive calcium oxide. Simultaneously, ultra-fine FA particles physically densify the interfacial transition zones, securely anchoring the steel fibers and preventing premature high-temperature pull-out, while enabling the fibers to bridge thermally induced macro-cracks successfully. Environmentally and economically, an annualized service-life Life Cycle Assessment (LCA) revealed that substituting 50% of the cement with FA completely subsidizes the production-stage carbon penalty of the metallic reinforcement. By extending the operational lifespan to 40 years, the CFA50-F composite achieves a net 27% reduction in annualized global warming potential, providing a highly sustainable and cost-effective material solution. Full article

Here, we report a highly efficient and stable catalytic system based on monometallic oxides supported on HY zeolites for the catalytic oxidation of chlorobenzene (CB). Among the transition and rare-earth metal oxides screened, the 30Cu/HY catalyst demonstrates exceptional performance, achieving near 100% CB conversion at 300 °C (500 ppm CB, 10,000 h⁻¹) alongside outstanding 24 h continuous stability without deactivation. Quantitative Py-IR analysis reveals that this superior activity is fundamentally driven by extensive solid-state ion exchange, forming robust Lewis acid centers (Cu-Y structures) that synergize with zeolitic Brønsted acid sites to efficiently polarize and cleave C-Cl bonds. Through an integrated approach combining in situ DRIFTS, real-time mass spectrometry, TGA, and NLDFT pore size analysis, we elucidate that the exceptional deep-oxidation capability of Cu/HY continuously mineralizes carbonaceous intermediates. This property minimizes coke deposition (2.91 wt%) and preserves the hierarchical pore architecture, preventing the coverage of active sites and severe pore blockage by partially oxidized intermediates (such as phenolic, aldehydic, and quinonic species) and stable carbonate species responsible for the deactivation of other metal oxides. These insights provide a mechanistic framework for the rational design of robust, chlorine-resistant catalysts for the sustainable abatement of persistent organic pollutants. Full article