Search Results (8,013)

This work investigated the effect of high-nitrogen/low-hydrogen mixed atmosphere heat treatment on the electrochemical corrosion and wear resistance of plasma-sprayed FeCoNiCrAl high-entropy alloy (HEA) coatings. The HEA coatings were sequentially prepared through annealing at 400, 600, and 800 °C for 6 h. The heat treatment method was conducted in a vacuum tube furnace under 0.1 MPa total pressure, with gas flow rates set to 300 sccm N₂ and 100 sccm H₂. The XRD results indicated that the as-deposited coating exhibited α-Fe (BBC) and Al_0.9Ni_4.22 (FCC) phases, with an Fe_0.64N_0.36 nitride phase generated after 800 °C annealing. The electrochemical measurements suggested that an exceptional corrosion performance with higher thicknesses of passive film and double-layer capacitance can be detected based on the point defect model (PDM) and effective capacitance model. Wear tests revealed that the friction coefficient at 800 °C decreased by 3.84% compared to that in the as-sprayed state due to the formation of a dense nitride layer. Molecular orbital theory pointed out that the formation of bonding molecular orbitals, resulting from the overlap of valence electron orbitals of different atomic species in the HEA coating system, stabilized the structure by promoting atomic interactions. The wear mechanism associated with stress redistribution and energy balance from compositional synergy is proposed in this work. Full article

Against the backdrop of accelerating global energy transition, developing high-performance energy-storage systems is crucial for achieving carbon neutrality. Traditional electrode materials are limited by a single densification storage mechanism and low conductivity, struggling to meet demands for high energy/power density and a long cycle life. Carbon/high-entropy alloy nanocomposites provide an innovative solution through multi-component synergistic effects and cross-scale structural design: the “cocktail effect” of high-entropy alloys confers excellent redox activity and structural stability, while the three-dimensional conductive network of the carbon skeleton enhances charge transfer efficiency. Together, they achieve synergistic enhancement via interfacial electron coupling, stress buffering, and dual storage mechanisms. This review systematically analyzes the charge storage/attenuation mechanisms and performance advantages of this composite material in diverse energy-storage devices (lithium-ion batteries, lithium-sulfur batteries, etc.), evaluates the characteristics and limitations of preparation techniques such as mechanical alloying and chemical vapor deposition, identifies five major challenges (including complex and costly synthesis, ambiguous interfacial interaction mechanisms, lagging theoretical research, performance-cost trade-offs, and slow industrialization processes), and prospectively proposes eight research directions (including multi-scale structural regulation and sustainable preparation technologies, etc.). Through interdisciplinary perspectives, this review aims to provide a theoretical foundation for deepening the understanding of carbon/high-entropy alloy composite energy-storage mechanisms and guiding industrial applications, thereby advancing breakthroughs in electrochemical energy-storage technology under the energy transition. Full article

To determine the structure of carbohydrate polymers using conventional analytical technology, several complicated steps are required. We instead adopted a direct approach without the need for pretreatments, using an intense infrared (IR) laser for carbohydrate analysis. IR free-electron lasers (FELs) driven by a linear accelerator possess unique spectroscopic features, including extensive wavelength tunability and high laser energy in the IR region from 1000 cm⁻¹ (10 μm) to 4000 cm⁻¹ (2.5 μm). FELs can induce IR multiphoton dissociation reactions against various molecules by supplying vibrational excitation energy to the corresponding chemical bonds. Chitin from crayfish and cellulose fiber were irradiated by FELs tuned to νC–O (9.1–9.8 μm), νC–H (3.5 μm), and δH–C–O (7.2 μm) in glycosidic bonds, and their low-molecular-weight sugars were separated, which were revealed by combining synchrotron radiation IR spectroscopy and electrospray ionization mass spectrometry. An intense IR laser can be viewed as a “molecular scalpel” for dissecting and directly analyzing the internal components in rigid biopolymers. This method is simple and rapid compared with general analytical techniques. Full article

We investigate TiAlZrTaNb nitride coatings deposited on Haynes 282 nickel superalloy substrates via high-power impulse magnetron sputtering (HiPIMS) under varying substrate bias voltages (0 V to −75 V). The influence of substrate bias on the microstructure, morphology, hardness, and wear resistance was systematically analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), nanoindentation, and ball-on-disk tribometry. The coatings exhibited a near equiatomic chemical composition with a face-centered cubic (FCC) crystal structure preferentially oriented along the (200) and (111) planes. Increasing the bias voltage reduced the grain size (3.65 nm to 2.84 nm) and lattice parameter (0.442 nm to 0.440 nm); meanwhile, the hardness (>45 GPa) and wear resistance were improved. The interplay between the deposition parameters and coating-substrate interactions are discussed in order to optimize HiPIMS-derived coatings for industrial applications. Full article

Despite notable advancements in lithium-ion battery (LIB) technology, growing industrialization, rising energy demands, and evolving consumer electronics continue to raise performance requirements. As the primary determinant of battery performance, cathode materials have become a central research focus. Among emerging candidates, iron-based fluorides show great promise due to their high theoretical specific capacities, elevated operating voltages, low cost (owing to abundant iron and fluorine), and structurally diverse crystalline forms such as pyrochlore and tungsten bronze types. These features make them strong contenders for next-generation high-energy, low-cost LIBs. This review highlights recent progress in iron-based fluoride cathode materials, with an emphasis on structural regulation and performance enhancement strategies. Using pyrochlore-type hydrated iron trifluoride (Fe₂F₅·H₂O), synthesized via ionic liquids like BmimBF₄, as a representative example, we discuss key methods for tuning physicochemical properties—such as electronic conductivity, ion diffusion, and structural stability—via doping, compositing, nanostructuring, and surface engineering. Advanced characterization tools (XRD, SEM/TEM, XPS, Raman, synchrotron radiation) and electrochemical analyses are used to reveal structure–property–performance relationships. Finally, we explore current challenges and future directions to guide the practical deployment of iron-based fluorides in LIBs. This review provides theoretical insights for designing high-performance, cost-effective cathode materials. Full article

Bismuth (Bi)-doped indium oxide (In₂O₃) has emerged as a promising thermoelectric material due to its tunable electrical and thermal properties. This study investigates the effects of Bi-doping on the thermoelectric performance of In₂O₃, focusing on its electrical conductivity, band structure, carrier concentration, mobility, Seebeck coefficient, power factor, thermal conductivity, and overall thermoelectric figure of merit (ZT). The incorporation of Bi into the In₂O₃ lattice significantly enhances the material’s electrical conductivity, attributed to the increased carrier concentration resulting from Bi acting as an effective dopant. However, this doping also leads to a broadening of the bandgap, which influences the electronic transport properties. The Seebeck coefficient (absolute value) is observed to decrease with Bi-doping, a consequence of the elevated carrier concentration. Despite this reduction, the overall power factor improves due to the substantial increase in electrical conductivity. Furthermore, Bi-doping effectively reduces both the total thermal conductivity and the lattice thermal conductivity of In₂O₃. This reduction is primarily due to enhanced phonon scattering caused by the introduction of Bi atoms, which disrupt the lattice periodicity and introduce point defects. The combined improvement in electrical conductivity and reduction in thermal conductivity results in a significant enhancement of the thermoelectric figure of merit (ZT) with highest ZT value increased from 0.055 to 0.402 at 973 K. The optimized Bi-doped In₂O₃ samples demonstrate a ZT value that surpasses that of undoped In₂O₃, highlighting the potential of Bi-doping for advancing thermoelectric applications. This work provides a comprehensive understanding of the underlying mechanisms governing the thermoelectric properties of Bi-doped In₂O₃ and offers valuable insights into the design of high-performance thermoelectric materials for energy conversion technologies. Full article

This study evaluated the feasibility of reusing abandoned copper mine tailings (Cu tailings) as a precursor in the production of fly-ash-based alkali-activated materials (FA-AAMs). Two formulations were developed by combining FA and Cu tailings with a mixture of sodium silicate and sodium hydroxide as alkaline activators at room temperature (20 °C). Formulation G1 consisted of 70% Cu tailings and 30% fly ash (FA), whereas G2 included the same composition with an additional 15% ordinary Portland cement (OPC). The materials were characterized using X-ray fluorescence (XRF), -X-ray diffraction (XRD), field emission scanning electron microscopy with energy-dispersive spectroscopy (FESEM-EDS), and particle size analysis. While FA exhibited a high amorphous content (64.4%), Cu tailings were largely crystalline and acted as inert fillers. After 120 days of curing, average compressive strength reached 24 MPa for G1 and 41 MPa for G2, with the latter showing improved performance due to synergistic effects of geopolymerization and OPC hydration. Porosity measurements revealed a denser microstructure in G2 (35%) compared to G1 (52%). Leaching tests confirmed the immobilization of hazardous elements, with arsenic concentrations decreasing over time and remaining below regulatory limits. Despite extended setting times (24 h for G1 and 18 h for G2) and the appearance of surface efflorescence, both systems demonstrated good chemical stability and long-term performance. The results support the use of Cu tailings in FA-AAMs as a sustainable strategy for waste valorization, enabling their application in non-structural and moderate-load-bearing construction components or waste encapsulation units. This approach contributes to circular economy goals while reducing the environmental footprint associated with traditional cementitious systems. Full article

Developing photocatalysts with both high efficiency and reaction pathway selectivity is essential for achieving efficient and sustainable CO₂ conversion. By incorporating sulphur vacancies into MoS₂, an S-scheme heterojunction photocatalyst (MoS₂-SVs/g-C₃N₄) was developed, achieving efficient and selective CO₂ photoreduction to CH₃OH. The structural and photoelectronic characterisation of the system shows that the heterogeneous interface between MoS₂ and g-C₃N₄ is in close contact. The introduction of SVs effectively modulates the electronic structure and surface activity of MoS₂, which in turn enhances the CO₂ reduction performance. Optical and electronic structure analyses reveal that the heterojunction promotes favourable band alignment and interfacial electric potential gradients, which together suppress charge recombination and enhance directional carrier separation. Under irradiation, the MoS₂-SVs/g-C₃N₄ photocatalyst exhibited outstanding photocatalytic CH₃OH production with a yield of 10.06 μmol·h⁻¹·g⁻¹, significantly surpassing the performance of control samples while demonstrating excellent product selectivity and remarkable stability. Mechanistic studies further verify that vacancy-induced energy band modulation with Fermi energy level enhancement significantly reduces the multi-electron transfer barrier, thus preferentially driving the CH₃OH generation pathway. This work proposes a universal structural design strategy that synergistically coordinates vacancy engineering with band structure modulation, establishing both theoretical principles and practical methodologies for developing selective multi-electron CO₂ reduction systems. Full article

In high-power insulated gate bipolar transistor (IGBT) module thermal management, the structural design of microchannel cooling plates plays a crucial role in determining heat dissipation efficiency and temperature uniformity. This study focuses on the effects of honeycomb-structured unit dimensions and arrangements, as well as inlet/outlet configurations of the cooling plate on its thermal and flow performance. Additionally, the influence of different coolant inlet velocities and temperatures is investigated. Under constant coolant flow rate and boundary conditions, four design configurations with varying pore widths and channel spacings were evaluated numerically. The results indicate that the optimized honeycomb structure can reduce the module’s peak temperature by approximately 8.7 K while significantly improving temperature uniformity and maintaining a moderate pressure drop. Moreover, increasing the number of inlets and outlets effectively lowers the pressure drop and enhances thermal uniformity. Although increasing the coolant flow rate and reducing the inlet temperature can further improve cooling performance, these measures also lead to notable increases in energy consumption and pressure loss. Therefore, a trade-off between thermal enhancement and system energy efficiency must be considered in practical applications. The findings of this study provide practical guidance for the design optimization of high-efficiency microchannel liquid cooling systems in power electronic applications. Full article

Gel-type electrofluorochromic (EFC) devices, which reversibly modulate photoluminescence under electrical stimuli, have emerged as versatile platforms for advanced optoelectronic applications. By integrating redox-active luminophores with soft, ion-conductive gel matrices, these systems combine the structural robustness of solids with the ionic mobility of liquids, enabling a high-contrast, flexible, and multifunctional operation. This review provides a comprehensive overview of gel-based EFC technologies, outlining fundamental working principles, device architectures, and key performance metrics such as contrast ratio, switching time, and cycling stability. Gel matrices are categorized into ionogels, organogels, and hydrogels, and their physicochemical properties are discussed in relation to EFC device performance. Recent advances are highlighted across applications ranging from flexible displays and rewritable electronic paper to strain and biosensors, data encryption, smart windows, and hybrid energy-interactive systems. Finally, current challenges and emerging strategies are analyzed to guide the design of next-generation adaptive, intelligent, and energy-efficient optoelectronic platforms. Full article

Graphene, a two-dimensional material with remarkable electrical, thermal, and mechanical properties, has revolutionized the fields of electronics, energy storage, and nanotechnology. This review presents a comprehensive analysis of graphene synthesis techniques, which can be classified into two primary approaches: top-down and bottom-up. Top-down methods, such as mechanical exfoliation, oxidation-reduction, unzipping carbon nanotubes, and liquid-phase exfoliation, are highlighted for their scalability and cost-effectiveness, albeit with challenges in controlling defects and uniformity. In contrast, bottom-up methods, including chemical vapor deposition (CVD), arc discharge, and epitaxial growth on silicon carbide, offer superior structural control and quality but are often constrained by high costs and limited scalability. The interplay between synthesis parameters, material properties, and application requirements is critically examined to provide insights into optimizing graphene production. This review also emphasizes the growing demand for sustainable and environmentally friendly approaches, aligning with the global push for green nanotechnology. By synthesizing current advancements and identifying critical research gaps, this work offers a roadmap for selecting the most suitable synthesis techniques and fostering innovations in scalable and high-quality graphene production. The findings serve as a valuable resource for researchers and industries aiming to harness graphene’s full potential in diverse technological applications. Full article

Co-combustion is regarded as an effective means for high-efficiency utilization of low-quality fuels. However, low-quality fuel has problems such as low energy density and high water content. The fuel quality and blending performance can be further optimized by the pretreatment of low-quality fuel, for example, calorific value, hydrophobicity, and NO conversion rate. Based on the idea of co-upgradation, this study systematically investigates the effects of integrated upgrading on fuel quality and hydrophobicity under different conditions. In this study, lignite and wheat straw were selected as research objects. The co-upgrading experiments of wheat straw and lignite were conducted at reaction temperatures of 170 °C, 220 °C, and 270 °C in flue gas and air atmospheres with biomass blending ratios of 0%, 25%, 50%, 75%, and 100%. SEM (scanning electron microscopy) and nitrogen (N₂) adsorption analyses showed that under low-temperature and low-oxygen conditions, organic components from biomass pyrolysis migrated in situ to cover the surface of lignite, resulting in a gradual smoothing of the fuel surface and a decrease in the specific surface area. Meanwhile, water reabsorption experiments and contact angle measurements showed that the equilibrium water holding capacity and water absorption capacity of the lifted fuels was weakened, and hydrophobicity was enhanced. Combustion kinetic parameters and pollutant release characteristics were investigated by thermogravimetric analysis (TGA) and isothermal combustion tests. It was found that co-upgradation could effectively reduce the reaction activation energy and NO conversion rate. Characterized by Raman spectroscopy (Raman) and X-ray photoelectron spectroscopy (XPS), in situ migration of organic components affected combustion reactivity by modulating changes in N-containing product precursors. The results showed that the extracted fuel with a 75% biomass blending ratio in the flue gas atmosphere exhibited the best overall performance at 220 °C, with optimal calorific value, combustion reactivity, and hydrophobicity. These findings may provide important theoretical foundations and practical guidance for the optimization of industrial-scale upgrading processes of low-quality fuels. Full article

The electrical properties of contacts to p-type nitride semiconductor devices, based on gallium nitride, were simulated by ab initio and drift-diffusion calculations. The electrical properties of the contact are shown to be dominated by the electron-transfer process from the metal to GaN, which is related to the Fermi-level difference, as determined by both ab initio and model calculations. The results indicate a high potential barrier for holes, leading to the non-Ohmic character of the contact. The electrical nature of the Ni–Au contact formed by annealing in an oxygen atmosphere was elucidated. The influence of doping on the potential profile of p-type GaN was calculated using the drift-diffusion model. The energy-barrier height and width for hole transport were determined. Based on these results, a new type of contact is proposed. The contact is created by employing multiple-layer implantation of deep acceptors. The implementation of such a design promises to attain superior characteristics (resistance) compared with other contacts used in bipolar nitride semiconductor devices. The development of such contacts will remove one of the main obstacles in the development of highly efficient nitride optoelectronic devices, both LEDs and LDs: energy loss and excessive heat production close to the multiple-quantum-well system. Full article

Structure–property relationships in imidazolium-based hybrid Sb(III) chlorides provide critical guidance for designing high-performance materials. Three zero-dimensional metal halides, namely, [C₃mmim]₂SbCl₅ (1, [C₃mmim]⁺ = 1-propyl-2,3-dimethylimidazolium), [C₅mmim]₂SbCl₅ (2, [C₅mmim]⁺ = 1-pentyl-2,3-dimethylimidazolium), and [C₅mim]₂SbCl₅ (3, [C₅mim]⁺ = 1-pentyl-3-methylimidazolium), are synthesized by ionothermal methods. These compounds exhibit markedly distinctly photophysical properties at their optimal excitation wavelengths. Structural analyses reveal that elongated alkyl chains in compounds 2 and 3 increase Sb–Sb distances compared to that in 1, effectively isolating [SbCl₅]²⁻ units, suppressing inter-center energy transfer, and reducing non-radiative transitions, thereby enhancing the photoluminescence quantum yield (PLQY). Furthermore, methyl substitution at the C2-position of the imidazolium ring in compounds 1 and 2 induces asymmetric coordination environments around the [SbCl₅]²⁻ emission centers, leading to pronounced structural distortion. This distortion promotes non-radiative decay pathways and diminishes luminescent efficiency. Furthermore, temperature-dependent spectroscopy analysis and fitting of the Huang–Rhys factor (S) reveal significant electron–phonon coupling in compounds 1–3, which effectively promotes the formation of self-trapped excitons (STEs). However, compound 1 exhibits extremely high S, which significantly enhances phonon-mediated non-radiative decay and ultimately reduces its PLQY. Overall, compound 3 has the highest PLQYs. Full article

The transport properties of biased type II superconductors are strongly influenced by external magnetic fields, which play a crucial role in optimizing the stability and performance of low-noise superconducting electronic devices. A major challenge is the stochastic behavior of Abrikosov vortices, which emerge in the mixed state and lead to energy dissipation through their nucleation, motion, and annihilation. Uncontrolled vortex dynamics can introduce electronic noise in low-power systems and trigger thermal breakdown in high-power applications. This study examines the effect of a perpendicular external magnetic field on vortex pinning in biased YBa₂Cu₃O_7-δ devices containing laser-written, rectangular-shaped, partially deoxygenated regions (δ ≈ 0.2). The results show that increasing the magnetic field amplitude induces an asymmetry in the concentration of vortices and antivortices, shifting the annihilation line toward a region of lower flux density and altering the flux pinning characteristics. Oxygen-deficient segments aligned parallel to the current flow act as barriers to vortex motion, enhancing the net pinning force by preventing vortex–antivortex pairs from reaching their annihilation zone. The current–voltage characteristics reveal periodic voltage steps corresponding to the onset and suppression of thermally activated flux flow and flux creep. These features indicate magnetic field–tunable transport behavior within a narrow range of temperatures from 0.94·T_c to 0.98·T_c, where T_c is the critical temperature of the superconductor. These findings offer new insights into the design of vortex-motion-controlled superconducting electronics that utilize engineered pinning structures. Full article