This study utilizes a effective field theory with correlations theory to explore the dynamic magnetic behavior and magnetocaloric effects of a two-dimensional decorated triangular husimi lattice. The lattice is composed of magnetic atoms with spin values of 3/2 and 1. The results indicate that variations in the exchange coupling |J| influence the system's saturation order parameter. Under specific parameter conditions, the magnetization susceptibility curve exhibits a double peak. A compensation phenomenon is also observed. The bias field (hb) and the oscillating field (ho) have opposite effects on the system's phase transition temperature. The study further examines the impact of various parameters on the magnetization, magnetic entropy change, relative cooling power (RCP), temperature-averaged entropy change (TEC), and normalized refrigerant capacity (NRC) of a ferromagnetic system. The findings demonstrate that strong exchange coupling reduces the material's RCP, TEC, and NRC. In contrast, a strong magnetic field enhances RCP and TEC while reducing NRC. These insights significantly deepen our understanding of magnetocaloric effects in two-dimensional materials. They also highlight their potential in developing more efficient and versatile magnetic devices.

The objective is to evaluate the magnetic behaviors of bilayer 2D nanomaterials with a Kagome lattice by employing the Monte Carlo method integrated with the Metropolis algorithm. This computational method is renowned for its accuracy in forecasting the magnetic properties of various nano-systems. We examine the order parameters and plateau effect, revealing that the exchange interactions and anisotropies are highly sensitive to the plateau number. Furthermore, we find that the application of a static bias field fosters magnetic ordering by aligning the spins, thereby enhancing the overall magnetization. In contrast, the introduction of an oscillating magnetic field induces a state of disorder, disrupting the alignment of the order parameter and leading to a reduction in the system's magnetization. Additionally, we analyze the magnetization versus time curve under different control parameters of the external magnetic field, such as hb, ho, and omega. This research provides valuable insights into the control of magnetic properties in advanced materials, with significant implications for experimental investigations and practical applications in fields like spintronics and magnetic storage.

MgH2 is a promising solid-state hydrogen storage material but limited by high thermal stability and sluggish dehydrogenation. While nanostructuring and adding catalysts improve its performance, MgH2 cluster agglomeration and the high loading of traditional metal catalysts reduce the effective hydrogen storage capacity. Therefore, developing novel two-dimensional (2D) catalysts for MgH2 is important. In this work, we employed first-principles calculations to explore the catalytic effect of the BC3 monolayer on improving the dehydrogenation performance of MgH2. The adsorption energies indicate that BC3 effectively confines the MgnH2n (n = 2-5) clusters and prevents their agglomeration. Among these, Mg5H10 adsorbed on BC3 exhibits the largest adsorption energy, reflecting the strongest interaction. Moreover, the BC3-supported Mg5H10 system considerably reduces the dehydrogenation enthalpy and energy barrier by more than 49% relative to the isolated Mg5H10 cluster. Compared with graphene, hexagonal boron nitride (h-BN), and boron (B) doped graphene, it demonstrates a clear catalytic performance trend: BC3 > B-doped graphene > graphene > h-BN. Mechanistic analyses reveal that B-C units in BC3 act as electron acceptors, facilitating charge transfer and weakening Mg-H bonds via interfacial orbital hybridization, contributing to its excellent catalytic behavior. This study establishes the BC3 monolayer as a high-performance catalyst for advanced hydrogen storage.

To overcome the sluggish kinetics and high operating temperatures of MgH2, we developed carbon-supported Fe5Ni4S8-Ni3S2 (FNS-NS/C) catalysts. The optimized MgH2+FNS-NS/C composite achieves an onset dehydrogenation temperature of 200 degrees C. Remarkably, it absorbs 5.26 wt% H-2 in 30 s at 175 degrees C and desorbs 6.22 wt% H-2 in 60 min at 300 degrees C, maintaining robust cycling stability (retaining 6.56 wt% over 10 cycles). Kinetic analysis reveals a dramatically reduced activation energy of 81.68 +/- 2.04 kJ mol(-1). This exceptional performance results from the synergistic interplay of the in-situ generated Mg2Ni "hydrogen pump", MgS/Fe-mediated diffusion channels, and carbon confinement. Furthermore, DFT calculations confirm that Mg2Ni, metallic Fe, and MgS cooperatively weaken the Mg-H bonds. This work establishes tailored sulfide/carbon hybrids as highly efficient promoters for practical solid-state hydrogen storage.

Single crystal superalloy scrap represents an important secondary resource containing rhenium (Re), yet only a very small fraction of high-purity scrap can be directly reused as remelting feedstock, while most of the material must undergo hydrometallurgical processing to enable Re recovery. In hydrometallurgical processes, the formation of oxide-dominated barrier layers hinders effective dissolution. To address this, an electrochemical leaching method using a mixed electrolyte of HCl and H2O2 was developed. The process parameters were optimized to 3 mol & sdot;L-1 HCl, 9% (v/v) H2O2, a current density of 0.36 A & sdot;cm-2, and an electrolysis time of 2 h. Under these conditions, the current efficiency reached 77% and the Re leaching efficiency was 97.9%. The barrier layers consisted of a chloride deposit layer, a Ta-W oxide layer, and a Cr-rich oxide layer. These layers were effectively broken down during the electrochemical process. Specifically, the Ta-W oxide layer underwent cracking and spallation, while the Cr-rich oxide layer was progressively destabilized and dissolved under the coupled chemical and electrochemical effects. This method successfully disrupted the oxide barrier layers and significantly enhances Re leaching efficiency. It provides an efficient nitric-acid-free route for recovering Re from single crystal superalloy scrap.

MgH2 is a promising solid-state hydrogen storage material but suffers from slow kinetics and high thermodynamic stability. This work designs a high-efficiency catalyst by anchoring MOF-derived FeOX/CoOX nanoparticles on Ni-functionalized Ti3C2ClX MXene/carbon nanocomposites. The unique interface provides strongly coupled active sites, promoting hydrogen dissociation, diffusion, and exchange. With only 7.5 wt% catalyst, the MgH2 composite achieves rapid uptake (similar to 6.2 wt% in 5 min at 150 degrees C) and release (similar to 6.8 wt% in 1 h at 300 degrees C), significantly reduced activation energy, and promising cycling stability with a capacity retention above 97% after 10 cycles. Mechanistic analysis reveals synergistic effects from in-situ-formed Mg2Ni/Mg2NiH4 hydrogen pumps, multivalent Ti-mediated electron transfer, and dispersed oxide sites. This study offers a feasible strategy for developing MXene-based catalysts to advance hydrogen storage systems.

Layered double hydroxides (LDHs)-derived ternary FeCoNi- and CrCoNi-mixed metal oxides (MMOs) were employed as high-efficiency catalysts to enhance the hydrogen storage performance of MgH2. The optimized MgH2-MMO composites significantly improved hydrogen storage kinetics, absorbing 5.92 wt% hydrogen within 2 min at 150 degrees C, far below the onset temperature of pure MgH2. Reversible dehydrogenation released 6.56 wt% hydrogen gas within 12 min at 310 degrees C, and the dehydrogenation activation energy dramatically decreased to 68.67 kJ/mol. Mechanistic studies indicate that in situ-formed Mg2NiH4 accelerates kinetics by destabilizing MgH bonds via strong electronic interactions, while CoO effectively suppresses particle agglomeration, ensuring excellent cycling stability. Additionally, highly dispersed amorphous Fe3 + and Cr3+ further promote hydrogen diffusion and reduce the barriers for both hydrogenation and dehydrogenation reactions. This work provides experimental insights and a novel framework for designing efficient catalysts to optimize MgH2-based hydrogen storage systems.

Based on Monte Carlo simulation, dynamic magnetic behaviors and the magnetocaloric effect of the double-layer MXene-like structure have been studied. The Ising model is employed to describe a double-layer MXene-like structure. Order parameters, susceptibility, and internal energy are discussed with various parameters. Additionally, hysteresis loops and coercivity are also depicted. We find that the exchange interaction, the amplitude, and the temperature are sensitive to the hoop number and the coercivity of the system. The presence of a bias field brings about order, whereas the oscillating magnetic field induces disorder. Besides, we also give the magnetic entropy changes and RCP of the double-layer MXene-like structure. These results have extensive application in spintronics, magnetic storage, and magnetic refrigeration.

The emergence of two-dimensional transition metal carbides/nitrides (MXene) has attracted extensive research interest. With a unique two-dimensional layered structure, MXene has a large specific surface area, excellent electrical conductivity, high mechanical strength and good stability, which make it highly promising in hydrogen storage and catalysis. It acts as a promising hydrogen storage material and improves the hydrogen storage capacity of metallic substrates, thus advancing the development of efficient and safe hydrogen storage systems. This review focuses on the structural features of MXene and clarifies their effects on hydrogen storage and catalytic performance. The preparation methods of MXene and its applications in hydrogen storage are also discussed. Moreover, the future prospects for MXene-based hydrogen storage materials are outlined, and the current bottlenecks and challenges in the development of MXene for hydrogen storage are explored. The insights from this review highlight the potential of MXene to address critical issues in hydrogen storage, such as low capacity and poor cycling stability, and provide guidance for future research to optimize synthesis processes and enhance the performance of MXene-based materials for practical applications.

Two-dimensional transition metal carbides (MXenes) are effective catalysts for enhancing the hydrogen storage performance of magnesium hydride (MgH2). However, their synthesis often involves hazardous conditions, such as hydrofluoric acid (HF), which limits practical applications. In this study, a Ni-doped Ti3C2ClX MXene was synthesized via a one-step molten salt method, avoiding HF and other hazardous acids and bases. This catalyst was incorporated into MgH2, significantly improving its hydrogen storage properties. Compared to conventional Ti3C2 MXene nanosheets prepared via HF etching, the Ni-Ti3C2ClX exhibited superior catalytic activity, enhancing the hydrogenation and dehydrogenation kinetics of MgH2. By optimizing catalyst loading, a balance between rapid hydrogen uptake/release rates and high storage capacity was achieved. The MgH2 composite with 7.5 wt% Ni-Ti3C2ClX released 6.59 wt% hydrogen within 3600 s at 300 degrees C, compared to 0.82 wt% for pristine MgH2under the same conditions. Additionally, the composite absorbed 5.95 wt% hydrogen within 1 h at 125 degrees C. The activation energy for dehydrogenation of the MgH2 + 7.5 wt% Ni-Ti3C2ClX composite was reduced to 79.6 kJ/mol, a 43.3 % decrease compared to pure MgH2. After ten hydrogenation/dehydrogenation cycles, the composite retained 98.8 % of its initial hydrogen storage capacity, demonstrating excellent cycling stability. Mechanistic studies revealed that the in-situ formed Mg2NiH4 phase acted as a "hydrogen pump," facilitating hydrogen diffusion, while multivalent titanium species enhanced electron transfer. These synergistic effects were crucial for the improved hydrogen storage performance of the composite.

Many studies have shown that the catalysts containing B, N, and Si elements significantly enhance the dehydrogenation process of MgH2. In present work, the Si2BN monolayer was chosen as the catalyst, and its effect on the dehydrogenation of MgH2 nanoparticles was systematically studied using first-principles calculations. The calculated binding energy indicates that the Si2BN monolayer effectively prevents the agglomeration of Mg5H10 cluster. More importantly, all the dehydrogenation enthalpies for Mg5H10 significantly decrease due to the catalysis of Si2BN. The dehydrogenation energy barrier of Mg5H10 on the Si2BN substrate is reduced by 0.8 eV when H5+H6 is released from the cluster compared to the undoped case. Analysing the electron densities, electron transfer, and density of states, it was found that the intrinsic mechanism of the catalytic effect of Si2BN on the Mg5H10 cluster originates from the formation of Mg-Si and H-Si chemical bonds at the Mg5H10/Si2BN interface. These chemical bonds not only tightly restrain the Mg5H10 to prevent its agglomeration, but also enlarge Mg-H bonds from 1.91 & Aring; to 2.00 & Aring;, leading to easier hydrogen release. The research suggests that the Si2BN monolayer is a promising catalyst with the ability to inhibit agglomeration, thus enhancing the dehydrogenation properties of MgH2 clusters.

Two-dimensional nanostructured materials offer abundant active sites, providing numerous pathways for diffusion and dissociation of hydrogen. CoFeLDH and NiFeLDH (LDH = layered double hydroxide) prepared by the co-precipitation method act as precursors, with their derivatives CoFeMMO and NiFeMMO (MMO = mixed metal oxide) being integrated into the MgH2 system. NiFeMMO doped MgH2 has shown impressive performance, absorbing 4.05 wt% hydrogen within 60 min at 75 degrees C and rapidly absorbing 5.72 wt% hydrogen within just 1 min at 150 degrees C. In contrast, CoFeMMO doped MgH2 absorbs 4.09 wt% hydrogen within 60 min at 150 degrees C, whereas milled MgH2 absorbs only 1.19 wt% hydrogen during the same period. The initial hydrogen release temperatures are lowered to 230 degrees C for CoFeMMO doped MgH2 and 200 degrees C for NiFeMMO doped MgH2, respectively. There is a significant reduction in the hydrogen release activation energies to 88.77 kJ/mol and 68.36 kJ/mol, respectively. Interestingly, NiFeMMO doped MgH2 demonstrates characteristics reminiscent of a "hydrogen pump" during hydrogenation and dehydrogenation by forming Mg2Ni/Mg2NiH4. This study highlights the promising potential of LDH-derived MMO catalysts in advancing hydrogen storage applications.

MgH2 is a promising solid-state hydrogen storage material, however, its kinetic properties and high operating temperature hinder practical applications. In this study, carbon-supported CoNi and FeNi bimetallic catalysts derived from metal-organic frameworks (MOFs) are designed and synthesized, demonstrating excellent catalytic effects on the hydrogen storage performance of the MgH2/Mg system. The initial dehydrogenation temperatures of MgH2 + CoNi/C and MgH2 + FeNi/C are 187 degrees C and 190 degrees C, respectively, which are 113 degrees C and 110 degrees C lower than that of pure MgH2. Notably, at 225 degrees C, these composites can absorb over 7 wt% H-2 within 1 h, while at 175 degrees C, hydrogen absorption exceeds 6.2 wt% in just 30 s. Complete dehydrogenation occurs at 300 degrees C, releasing >6.4 wt% H-2, with activation energies of 75.1 kJ mol(-1) and 70.9 kJ mol(-1) for the MgH2 + CoNi/C and MgH2 + FeNi/C composites. After 10 cycles, the hydrogen storage capacity remains at 6.6 wt%. Mechanistic analysis reveals that CoNi/C and FeNi/C are uniformly distributed on the surface of MgH2 particles, providing heterogeneous catalytic active sites and numerous hydrogen diffusion pathways, facilitating hydrogen adsorption and dissociation. This study presents an innovative approach for designing cost-effective and highly efficient carbon-supported bimetallic catalysts.

A gradient design of material is an effective way to solve the inhomogeneity of current-carrying damage. However, service conditions have a great influence on the current-carrying damage of gradient composites. To promote the development and application of current-carrying friction materials, it is necessary to elucidate the current-carrying damage mechanism of gradient composites with different service conditions. To this end, the gradient copper-graphite composites were prepared by hot pressing and sintering, and the variation in the current-carrying properties of the composites with loads were investigated in this study. The results showed that with increasing load, the wear rate of the composites initially decreased and then increased, while the currentcarrying properties initially improved and then deteriorated. The composite exhibited better current-carrying tribological performance at the load of 55 N, and the wear rate of the composite was 1.59 x 10-4 mm3 N- 1 m- 1. Meanwhile, the current carrying efficiency and current carrying stability was 98.5 % and 2.2 %, respectively. The main wear mechanism of the composite at 55 N was plastic deformation.

The development of efficient, stable, and cost-effective multifunctional electrocatalysts was crucial for water electrolysis. This study introduced MoGe₂P₂As₂, a novel two-dimensional monolayer material with Janus semiconductor properties, derived from atomic doping of MoGe2N4. Various single-atom doped configurations (TM@MoGe₂P₂As₂, where TM = Fe, Co, Ni, Cu, Ru, Rh, Ag) were synthesized. Using Density Functional Theory (DFT), we analyzed their structural integrity, electronic properties, and catalytic efficiencies for the Hydrogen Evolution Reaction (HER), Oxygen Evolution Reaction (OER), and Oxygen Reduction Reaction (ORR). Notably, Ru@MoGe₂P₂As₂ exhibited exceptional trifunctional electrocatalytic performance, with a Gibbs free energy for HER of -0.13 eV (superior to platinum) and lower overpotentials for OER (0.12 V) and ORR (0.23 V). Its OER activity surpassed that of RuO2, and its ORR efficiency exceeded Pt (111). Furthermore, the application of volcano plots and the establishment of linear correlations between intermediate free energies validated ΔGOOH*-ΔGOH* and ΔGOH* as reliable descriptors for OER and ORR activities, respectively. Analysis of the d-band center theory and electronic structure provided deep insights into the underlying catalytic mechanisms. This research highlighted the potential of MoGe₂P₂As₂ based materials in designing next-generation multifunctional electrocatalysts, offering new perspectives for their practical applications.

As a novel magnetism that combines features of ferromagnetism and antiferromagnetism, altermagnetism is attracting great attention due to its special energy band structure and potential application prospects. The NiAs-type metallic CrSb was proposed to be a new altermagnet, which has been experimentally verified by spin-resolved angle-resolved photoemission spectroscopy. In this work, we show the magnetic, electrical, and thermoelectric properties of CrSb single crystals. It is found that the thermoelectricity exhibits an anomalous Nernst effect (ANE) with the value of |SzAy| similar to 0.3 mu V/K, which is comparable to the value in the ferromagnetic metals. In addition, first-principles calculation shows that the experimental results are qualitatively consistent with the characteristics of an altermagnet and support the observation of ANE. This work not only provides a splendid bulk platform to study altermagnet physics, but also indicates that ANE is a highly effective method to study alternating spin-splitting band structure near the Fermi level and will greatly intrigue the research interest of ANE in altermagnets.

Electron-phonon interactions (EPIs) represent a fundamental cornerstone of condensed matter physics, commanding persistent attention due to their pivotal role in driving novel quantum phenomena within low-dimensional materials. Here, we unveil unusual anisotropic electron-phonon coupling behaviors in quasi-one-dimensional Ta_2Ni_3Te_5 nano-flakes through a powerful combination of angle-resolved polarized Raman spectroscopy and density functional perturbation theory (DFPT). High-resolution transmission electron microscopy and scanning tunneling microscopy directly visualize the pronounced quasi-one-dimensional atomic chains within the crystal structure, establishing a structural foundation for the observed anisotropic interactions. Our Raman investigations reveal remarkable polarization-dependent responses in A_g phonon modes that deviate significantly from conventional behavior, which our theoretical analyses attribute to complex anisotropic electron-photon and electron-phonon interactions. Temperature-dependent Raman measurements further uncover an intriguing phonon decay mechanism involving both three- and four-phonon processes, with the latter showing significant contributions in some modes - a possible manifestation of strong anisotropic electron-phonon interactions. Beyond revealing Ta_2Ni_3Te_5 as an exceptional platform for exploring anisotropic EPIs, this work demonstrates that integrating angle-resolved polarized Raman spectroscopy with DFPT calculations offers a powerful methodology for investigating electron-phonon interactions in emerging low-dimensional quantum materials.