Search Results (546)

This study presents a transient computational fluid dynamics (CFD) analysis of dielectric flow behaviour and debris transport in micro-EDM milling, considering the effects of dielectric properties, inter-electrode gap (IEG) size (20–30 µm), and tool rotational speed (400–850 rpm). Four dielectric media, nitrogen gas, deionized water, HEDMA111 EDM oil, and sunflower seed oil, were investigated using a two-dimensional FEM-based model coupled with particle tracking simulations to evaluate debris mobility within the machining region. The results demonstrate that dielectric properties, particularly viscosity, strongly influence hydrodynamic behaviour and particle transport within the IEG. Under the adopted equal mass flow rate condition, nitrogen gas exhibited the highest flow velocities and the fastest debris evacuation due to the combined effects of its low viscosity and the resulting higher inlet velocity. Deionized water and HEDMA111 oil exhibit comparable intermediate behaviour, indicating that moderate viscosity variations within liquid dielectrics do not significantly alter the overall flow regime. In contrast, sunflower seed oil generates the most damped flow conditions, with reduced velocities and prolonged particle residence due to increased viscous resistance. Variations in IEG size produce only minor changes in evacuation efficiency compared with the dominant influence of dielectric properties, while tool rotational speed primarily affects velocity magnitude without altering qualitative transport behaviour. Full article

Alkaline nickel zinc batteries feature high safety, low cost and eco-friendly characteristics, making them highly promising for large-scale energy storage deployment. However, their practical application is severely constrained by the cathode’s electrical conductivity, available active sites, and cycling stability. Herein, vertical 2D hierarchical flake-like NiCoS_x arrays were in situ grown on nickel foam (NF) via a facile alkali-free solvothermal and in situ sulfidation approach. This highly interconnected and open porous flaky structure significantly shortens the ion diffusion pathways, exposes abundant redox-active sites, and accelerates electron transport, imparting excellent rate performance and superior long-cycle stability to the material. The optimized NiCoS_x/NF electrode achieves a high specific capacity of 323 mAh g⁻¹ at 0.5 A g⁻¹, along with excellent capacity retention capability. Assembled with a commercial Zn anode, the NiCoS_x/NF//Zn full battery delivers 124 mAh g⁻¹ at 3 A g⁻¹, and maintains 112.5% of the initial capacity after 500 cyclic tests. Moreover, the assembled NiCoS_x/NF//Zn full cell possesses a high energy density of 615.2 Wh kg⁻¹ along with a power density of 38.6 kW kg⁻¹ (based on the mass of positive electrode active materials). This unique vertical 2D open hierarchical structure plays a crucial role in enhancing the electrochemical performance of cobalt sulfide cathodes and provides valuable insights for the design of high-performance alkaline zinc-based battery electrodes. Full article

Lithium-ion batteries with high energy density and long cycle life have been widely used as secondary batteries in electric vehicles and energy storage systems. With the growing demand for high energy density in lithium-ion batteries, silicon-based materials, which possess a high theoretical specific capacity (4200 mAh g⁻¹), are regarded as core candidates for anode materials. However, Si-based materials undergo severe volume expansion (up to 300%), which leads to the collapse of the electrode structure, inducing pulverization of the active material and capacity loss, thereby hindering the commercial application of silicon-based materials. To address these issues, scholars from various countries have developed many silicon-based materials with different compositions and three-dimensional structures, and have made some research progress. This review first elaborates on the lithium storage mechanisms and advantages of diverse silicon-based anode materials by taking Si, SiO_x, SiN_x, and SiP_x as representative examples with distinct characteristics. Subsequently, from the two aspects of dimensional design (0D, 1D, 2D and 3D) and architecture design (core–shell, sandwich-like and network structure), the design strategies for various silicon-based anode structures and their enhancement on electrochemical performance are analyzed. Finally, this review elucidated the challenges faced by silicon-based anodes from the perspectives of mechanism elucidation, structural customization, industrialization, and full-cell applications. It also proposed future development directions for silicon anodes by combining actual challenges and focusing on aspects such as structure optimization, machine learning, advanced characterization techniques, and mechanistic analysis. Full article

Marine diesel engines generate high concentrations of sub-micron particulate matter (PM) that requires effective exhaust aftertreatment. While conventional wire-in-tube electrostatic precipitators (ESP) offer a low-drag solution, their practical efficiency is limited by particle re-entrainment at elevated flow velocities. This study investigates a novel application of corrugated cylindrical ducts—standard vibration-compensating couplings—as electrostatic collectors. A fully coupled two-dimensional axisymmetric COMSOL Multiphysics 6.4 model was developed, integrating turbulent flow (k–ε), electrostatics, ion charge transport, and particle tracing. Numerical results demonstrate that while smooth and corrugated geometries yield identical theoretical Deutsch–Anderson efficiency (61.1% at Uin = 0.5 m/s, the corrugated profile significantly suppresses re-entrainment. The corrugations reduce wall shear stress by a factor of 7.7 to 13.5 at flow velocities of 0.3–0.8 m/s, maintaining aerodynamic conditions below critical particle detachment thresholds. With a pressure drop penalty representing less than 6% of the localized corona power, these findings show that existing marine exhaust infrastructure can be repurposed as high-efficiency, low-re-entrainment particle collectors through the integration of cold plasma electrodes. Full article

To address contact-limited transport commonly encountered in two-dimensional semiconductors, this study fabricated few-layer two-dimensional molybdenum disulfide (MoS₂) films on sapphire substrates via controllable oxide-to-sulfide conversion. Combined sputtering deposition of molybdenum trioxide and precise chemical-vapor sulfidation afforded high-quality, high-uniformity, and thickness-tunable MoS₂. The resulting films exhibit distinct differences in the frequencies of the Raman modes, consistent elemental ratios, and uniform interlayer spacing of ~0.65 nm. The MoS₂-based devices exhibit robust photodetection with microampere-scale photocurrents. Bilayer MoS₂ exhibited negative photoconductivity under ambient atmosphere, which is hypothesized to be linked to environment-induced surface doping and molecular adsorption rather than permanent structural traps. Contact engineering via mild thermal annealing of Ni electrodes significantly enhanced the photocurrent by improving effective interfacial carrier injection. These findings underscore the oxide sulfidation strategy as a scalable approach for engineering the layer-dependent behavior of transition metal dichalcogenides for optoelectronic applications. Full article

Van der Waals (vdW) multiferroic tunnel junctions (MFTJs) based on two-dimensional layered materials have emerged as a promising platform for next-generation non-volatile memory devices. In this work, we propose and theoretically investigate a high-performance all-vdW MFTJ consisting of a sliding ferroelectric bilayer GeC barrier sandwiched between asymmetric ferromagnetic metallic electrodes, Fe₃GaTe₂ and Fe₃GeTe₂. Using first-principles calculations combined with the non-equilibrium Green’s function (NEGF) method, we demonstrate that the bilayer GeC possesses robust vertical ferroelectricity switchable by interlayer sliding. By incorporating monolayer graphene as protective layers to mitigate metal-induced gap states, the device preserves the intrinsic ferroelectric polarization of the barrier. Our results reveal that four distinct non-volatile resistance states can be realized by independently manipulating the ferroelectric polarization and magnetization configurations. Remarkably, the device exhibits a giant Tunneling Magnetoresistance (TMR) ratio of up to 750.95% and a large Tunneling Electroresistance (TER) ratio of 322.97%. Furthermore, we observe perfect spin-filtering efficiency and a significant negative differential resistance (NDR) effect under finite bias voltage. These findings suggest that the Fe₃GaTe₂/graphene/bilayer-GeC/graphene/Fe₃GeTe₂ heterostructure is a compelling candidate for multifunctional spintronic applications in the post-Moore era. Full article

Given its high energy density and environmentally benign nature, hydrogen has emerged as a sustainable alternative to conventional fossil fuels. Consequently, water electrolysis has attracted considerable attention as a hydrogen production method, with the design of efficient and durable catalytic materials representing a crucial research focus. Herein, we design a two-dimensional metal–organic framework (MOF) for hydrogen evolution electrocatalysis using density functional theory calculation. V₃(C₆O₆)₂, Cr₃(C₆O₆)₂ and Co₃(C₆O₆)₂ emerge as potentially viable, meeting dual criteria of thermodynamic stability and optimal catalytic activity. Notably, Cr₃(C₆O₆)₂ demonstrates unexpectedly high hydrogen evolution reaction (HER) activity comparable to Pt-based catalysts, owing to the moderate H-s/Cr-d-orbital hybridization that fine-tunes H binding. The findings provide substantial theoretical guidance for developing advanced electrocatalysts for sustainable hydrogen evolution. Full article

Ni coarsening is a primary degradation mechanism in Ni-based anodes, significantly contributing to performance decline and diminished lifespan of methane steam reforming solid oxide fuel cells (SOFCs) during long-term operation. In this study, a novel algorithm is introduced to reconstruct two-dimensional Ni-YSZ anode microstructures, complemented by the development of a multi-physics model that integrates phase-field modeling (PFM) with the Lattice Boltzmann Method (LBM). This coupled PFM-LBM framework is employed to investigate the effects of Ni agglomeration on microstructural evolution and methane-steam mass transport under diverse conditions. The results demonstrate that the initial Ni particle diameter exerts a significant influence on Ni agglomeration dynamics. Furthermore, the mass transport analysis reveals that the necking structures formed during Ni coarsening pose a substantial impediment to mass transfer efficiency. Finally, optimized structural parameters for Ni-YSZ are proposed to enhance anode performance in Ni-based electrodes. Full article

Nonaqueous potassium-ion batteries (KIBs) are emerging as promising next-generation energy storage systems owing to their abundant resources and high energy density. However, their large-scale application is hindered by structural degradation and sluggish kinetics resulting from the large ionic radius of K ions. Engineering electrode materials with open frameworks, such as two-dimensional (2D) layered structures, present an effective strategy to address these challenges by providing rapid ion diffusion pathways and robust host structures. Herein, a rational interlayer engineering strategy is developed by intercalating phenylamine derivatives with varying molecular sizes (P-butylaniline: PTA, P-Methylaniline: PMA, and phenylamine: PA) into layered 2D VOPO₄ nanosheets. The intercalation of PANI derivatives progressively expands the interlayer spacing from 0.76 nm (pristine VOPO₄) to 1.58, 1.85, and 2.09 nm, while maintaining the structural integrity of the layered framework. Notably, the regulated interlayer expansion (from 0.76 to 2.09 nm) not only provides enlarged diffusion pathways for rapid K⁺ ion intercalation/deintercalation kinetics, but also facilitates the formation of oxygen vacancies that may serve as additional active sites for potassium storage. By correlating the electrochemical performance with the modulated interlayer distances, it is established that a preferred spacing of 1.85 nm achieves the best synergy between fast kinetics, high capacity, and structural stability. As expected, the electrode with the optimal interlayer spacing (1.85 nm) exhibits superior potassium-ion storage performance, delivering a high reversible capacity of 333.2 mAh g⁻¹ at 0.1 A g⁻¹ over 100 cycles and exceptional rate capability with 205.7 mAh g⁻¹ retained at 1 A g⁻¹, as well as maintaining remarkable stability up to 600 cycles even at high rates. This work innovatively proposes phenylamine derivative-enabled interlayer regulation as a promising approach for designing high-performance VOPO₄-based electrode materials. Full article

Proton exchange membrane water electrolysis is a promising technology for large-scale green hydrogen production due to its high efficiency, compact design, and rapid dynamic response. However, its commercialization is strictly limited by high material costs, durability issues, and complex multiphysics coupling within the membrane electrode assembly. This work provides a comprehensive and critical review of key physicochemical processes and advanced predictive modeling approaches for PEMWEs. To capture recent paradigm shifts, we introduce an innovative multi-dimensional classification framework—incorporating spatial resolution, temporal dynamics, and methodological paradigms—to critically evaluate lumped-parameter, continuum, microscale, and multiscale models, explicitly defining their applicability bounds and inherent limitations. The fundamental mechanisms governing electrode kinetics, membrane water transport, and gas–liquid two-phase flow are analyzed, establishing state-of-the-art quantitative benchmarks for microstructural parameters and advanced 3D flow field topologies under high-current-density and high-pressure regimes. Furthermore, we systematically examine model validation rigor, typical prediction errors, and the critical failure of static models in capturing dynamic property shifts during extreme bubble breakthrough. Recent breakthroughs integrating in situ diagnostics, pore-scale simulations, density functional theory, and Physics-Informed Neural Networks are extensively discussed. Future efforts must prioritize mechanical–electrochemical–thermal coupling, transient degradation prognostics, and machine learning-driven predictive digital twin technologies to overcome current empirical limitations and accelerate the gigawatt-scale deployment of PEMWE systems. Full article

Electrochemical oxidation (EO) possesses numerous advantages and great potential for organic pollutant degradation. However, traditional plate anodes for EO are limited by pollutant mass transfer, leading to low oxidation efficiency and high energy consumption. Herein, a three-dimensional (3D) polyacrylonitrile-based carbon fiber brush (PAN-CFB) anode was employed to enhance mass transfer and improve oxidation efficiency. The oxidation capacity of the PAN-CFB anode was compared with those of boron-doped diamond (BDD) and Ti/IrO₂-Ta₂O₅ plate anodes using oxalic acid (OA), phenol, and perfluorooctanoic acid (PFOA) as target pollutants, respectively. Experimental results demonstrated that the 3D PAN-CFB anode exhibits superior direct oxidation capacity compared to BDD and the Ti/IrO₂-Ta₂O₅ plate anode in degrading OA, which is attributed to the significantly enhanced mass transfer of OA toward the brush anode surface. Under a constant current of 400 mA for 240 min, the total organic carbon (TOC) removal from 50 mmol/L OA reached 90.5%, 57.5% and 6.6% for PAN-CFB, BDD and the Ti/IrO₂-Ta₂O₅ anode, respectively, and the energy consumption followed the order of PAN-CFB (5.5~8.9 kWh/kg_TOC) < BDD (11.2~19.3 kWh/kg_TOC) < Ti/IrO₂-Ta₂O₅ (76.1~120.7 kWh/kg_TOC). However, the 3D PAN-CFB anode exhibited poor stability at high potential and failed to promote phenol and PFOA degradation due to the weak direct oxidation capacity toward the two pollutants and the poor generation capacity of reactive oxygen species, associated with its low oxygen evolution potential. Therefore, future efforts should focus on developing stable 3D brush electrodes with a higher oxygen evolution potential to enable non-selective oxidation of a broader range of pollutants. Full article

As low-temperature plasmas (LTPs) have gained significant attention in materials processing for the microelectronics industry, challenges in spatiotemporal analysis of plasma parameters in a radio frequency capacitively coupled plasma (RF-CCP) system necessitate multidimensional numerical simulations. This study investigated the conditions under which a kinetic simulation or a fluid model is effective for low-pressure CCPs, focusing on the critical role of energy-dependent electron kinetics in LTPs by comparing symmetric and asymmetric electrode structures. We provide a comprehensive investigation of particle energy distributions, elucidating the kinetic effects of non-Maxwellian distributions. The validity of standard fluid approximations, such as the drift–diffusion approximation and isotropic pressure assumptions, is assessed by comparing results from a two-dimensional fluid model with those from a particle-in-cell simulation. The dominance of the ion pressure tensor over isotropic approximations in the sheath has been observed, especially in an asymmetric electrode structure, which is more representative of realistic process chambers. Full article

Innovations in nanomaterial science, engineering and printing technologies have increasingly driven advances in electrochemical sensing. Screen-printed electrodes (SPEs) have become a versatile, low-cost, and scalable solution for developing portable electrochemical detection platforms. However, their analytical performance remains intrinsically limited by surface area, electron transfer efficiency, and the immobilization of biomolecules. Recent developments in nanostructured materials, ranging from two-dimensional (2D) materials such as graphene, MXenes, and transition metal dichalcogenides, to one-dimensional nanostructures and hybrid nanocomposites, have transformed the signal transduction landscape of SPE-based electrochemical sensors. Integration of nanomaterials into SPEs has successfully transformed their analytical capabilities, but the diversity of materials and modification strategies has made it difficult to consolidate current knowledge in the field. Strategies that integrate nanomaterials via ink formulation, surface modification, or in situ growth have yielded sensors with unprecedented sensitivity, reproducibility, and selectivity across various chemical and biological targets. This review offers a cross-material synthesis of how nanomaterial engineering transforms the electrochemical performance of SPEs. By integrating insights across morphology, interfacial chemistry, and device-level behavior, it establishes a unified perspective that has been missing from the current literature and clarifies the design principles driving next-generation SPE-based sensing platforms. 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

Dopamine (DA) is a crucial catecholamine neurotransmitter, and its abnormal levels are closely associated with neurological disorders such as Parkinson’s disease. Electrochemical sensing technology offers a rapid and cost-effective platform for DA detection; however, it often suffers from interference from coexisting biomolecules such as ascorbic acid (AA) and uric acid (UA). In this study, we report a novel electrochemical biosensor based on PdMo bimetallene, a nanomaterial synthesized via a facile wet-chemical approach, aiming to enhance the detection performance and selectivity for DA. PdMo bimetallene is a highly curved, atomically thin two-dimensional nanosheet featuring abundant strained sites and a high density of active centers, enabling the selective and sensitive detection of DA. The results demonstrate that the as-prepared PdMo bimetallene-modified glassy carbon electrode (GCE) exhibits excellent electrocatalytic activity toward the oxidation of DA. The sensor displays a good linear response over the concentration range from 10 nM to 200 µM, with an ultrahigh sensitivity of 80 µA·µM⁻¹ cm⁻² and a low detection limit of 0.14 µM (S/N = 3). Owing to the synergistic electronic effect between Pd and Mo, the high density of exposed active sites, and the unique strained lattice structure of the bimetallene, the sensor enables accurate determination of DA concentrations even in the presence of interfering species such as AA and UA. In summary, the successfully fabricated PdMo bimetallene-based sensor offers the advantages of low cost, facile synthesis, a wide linear range, and high sensitivity, positioning it as a promising candidate for neurotransmitter detection applications. Full article