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Strain engineering has been proved to be an effective approach to modulate various physical properties in two-dimensional (2D) materials with flexible structures. In this work, based on first-principles calculations, the impact of in-plane biaxial tensile strain on lattice thermal conductivity of bilayer MoSe2, involving different stacking modes, has been systematically investigated by iteratively solving phonon Boltzmann transport equation. Simultaneously, potential regulations of interfacial anharmonic effect in phonon transport via in-plane strain can also be clarified through a comparative study between the monolayer and bilayer cases. Our results indicate that thermal transport in both the monolayer and bilayer MoSe2 is governed by low-frequency phonon branches, and the bilayer exhibits a notably reduced thermal transport capacity due to interlayer interaction existing in van der Waals homogeneous stacks. As the in-plane tensile strain is applied, a significant suppression in thermal transport capacity per layer can be further achieved in both the monolayer and bilayer cases, implying great potential for effective thermal management in 2D MoSe2 via strain engineering. Besides, the role of homogeneous interface in phonon transport of bilayer MoSe2 can also be regulated by the exerted in-plane tensile strain, which slows the decline in thermal conductivity with strain and leads to a larger thermal sheet conductance in the strained bilayer compared to the monolayer. [ABSTRACT FROM AUTHOR]

[Display omitted] With the ever-growing demand for high-capacity energy storage technologies, lithium-ion batteries (LIBs) have drawn increasing attention. Ti 2 B 2 , a typical two-dimensional MBenes material, has been considered as a strong contender for anode materials of LIBs with significant performance. However, the limited Li storage capacity of MBenes has hindered its wide applications. To address this issue, we have functionalized Janus-structured MBenes, denoted as Ti 2 B 2 X a X b (X a /X b = N, O, S, Se). Employing first-principles simulations based on density functional theory, we have investigated the geometric characteristics and electrochemical properties of Ti 2 B 2 X a X b. Our results reveal that Ti 2 B 2 NO exhibits an exceptionally large theoretical specific capacity of 1091.17 mAh·g−1, improved by 2.4 times compared with the pristine Ti 2 B 2 (456 mAh·g−1). Li atoms on the O side of Ti 2 B 2 NO possess a low diffusion barrier of 0.33 eV, which is conducive to the rapid charging and discharging of the battery. Moreover, the open-circuit voltage of Ti 2 B 2 NO within the safe voltage range of 0–1 V ensures the safety of battery operation. Overall, our study sheds light on understanding the underlying mechanism of surface functionalization on the Li storage properties of Janus-structured MBenes from atomic-scale, laying the groundwork for future design of high-performance anode materials. [ABSTRACT FROM AUTHOR]

Context: Two-dimensional (2D) nanoheterostructures of materials, integrating various phase or materials into a single nanosheet have stimulated large-scale research interest for designing novel two dimensional devices. In contemporary analysis present work, we examined the structural and electronic properties of the isolated 2D BN and GaN monolayers. We have investigated the structural stability and optoelectronic and photocatalytic response of the g-GaN/BN nanoheterostructure along with its response to strain. Nanoheterostructure g-GaN/BN is predicted to be a direct bandgap semiconductor with wide gap of 4.45 eV, whose value can be effectively modulated by applied strain ( ϵ) , ranging from 4.55 (ϵ = − 4%) to 3.58 eV (ϵ = 8%). We also discovered that the tensile strain of 8% can substantially tune the direct bandgap of nanoheterostructure to indirect band gap nature. Even more important, the biaxial tensile strain engineering accentuates an enhancement of optical absorption in the UV region, broadening the light harvesting of the g-GaN/BN nanoheterostructure with the shifting of first absorption peak from 4.64 (ϵ = − 4%) to 3.71 eV (ϵ = 8%). Furthermore, strain-tuned band edge potentials arrangement perfectly fits the water reduction and oxidation redox potentials. Our findings portend that the g-GaN/BN nanoheterostructure has application in prospective nanoscale optoelectronic devices and photocatalytic hydrogen evolution system. Methods: First principles calculations in this study are performed using density functional theory. Generalized gradient approximation within PBEsol functional employed to address the electron–electron exchange–correlation effects. For avoiding periodic interactions between the layers, we have inserted a vacuum region of thickness 10 Å in the z-direction. For ensuring the convergence accuracy of the computed results, convergence criteria of the iteration process is set to be 0.0001 eV. Local modified Becke–Johnson, a semi local functional, is applied for calculating electronic and optical properties for more accuracy of results. As in layered 2D nanoheterostructure, a factual depiction of the van der Waals interactions cannot be provided by conventional DFT techniques. Accordingly, in order to incorporate these interactions, we had employed the dispersion correction method of Grimme's. [ABSTRACT FROM AUTHOR]

To study the high pressure behavior of metal tetrahydrides, here, we apply the first-principles method to study the influence of pressure on the structural stability, mechanical, electronic and optical properties of two TMH 4 (TM = Ti and V) tetrahydrides. The calculated results show that although the formation enthalpy of two TMH 4 increases with increasing pressure, two TMH 4 tetrahydrides are thermodynamic stability under high pressure. In particular, the VH 4 has better thermodynamic stability in comparison to TiH 4 under pressure. Furthermore, the calculated elastic modulus of TMH 4 increases with increasing pressure. The VH 4 has strong deformation resistance and high elastic stiffness in comparison to TiH 4 under pressure. Essentially, the structural stability and mechanical properties of TiH 4 and VH 4 are related to the formation of TM-H bond in TMH 4. However, the pressure weakens the shear deformation resistance and elastic stiffness of TMH 4 when the pressure is bigger than 70 GPa. In addition, two TMH 4 tetrahydrides show electronic properties. In particular, the pressure enhances the electronic interaction of TiH 4 and VH 4 near the Fermi level, which is beneficial to store a mass of hydrogen. Finally, it is found that the pressure induces the main peak of TMH 4 to occur migration from low energy region to the high energy region. [ABSTRACT FROM AUTHOR]

• Evolution law of long-period stacking ordered phase (LPSO) in Mg-Gd-Y-Zn alloy and its effect on mechanical properties were investigated. • First-principles calculations for 14H and 18R LPSO phases regarding thermodynamic and mechanical properties were carried out. • Superlattice structure of the LPSO phase folds the fermi surface of the brillouin zone, resulting in an increase in the elastic modulus of the LPSO phase. • Long-range interactions caused by the LPSO phase play a crucial role in suppressing dislocation motion. Based on experiments and first-principles calculations, the microstructures and mechanical properties of as-cast and solution treated Mg-10Gd-4Y-xZn-0.6Zr (x = 0, 1, 2, wt.%) alloys are investigated. The transformation process of long-period stacking ordered (LPSO) structure during solidification and heat treatment and its effect on the mechanical properties of experimental alloys are discussed. Results reveal that the stacking faults and 18R LPSO phases appear in the as-cast Mg-10Gd-4Y-1Zn-0.6Zr and Mg-10Gd-4Y-2Zn-0.6Zr alloys, respectively. After solution treatment, the stacking faults and 18R LPSO phase transform into 14H LPSO phase. The Enthalpies of formation and reaction energy of 14H and 18R LPSO are calculated based on first-principles. Results show that the alloying ability of 18R is stronger than that of 14H. The reaction energies show that the 14H LPSO phase is more stable than the 18R LPSO. The elastic properties of the 14H and 18R LPSO phases are also evaluated by first-principles calculations, and the results are in good agreement with the experimental results. The precipitation of LPSO phase improves the tensile strength, yield strength and elongation of the alloy. After solution treatment, the Mg-10Gd-4Y-2Zn-0.6Zr alloy has the best mechanical properties, and its ultimate tensile strength and yield strength are 278.7 MPa and 196.4 MPa, respectively. The elongation of Mg-10Gd-4Y-2Zn-0.6Zr reaches 15.1, which is higher than that of Mg-10Gd-4Y0.6Zr alloy. The improving mechanism of elastic modulus by the LPSO phases and the influence on the alloy mechanical properties are also analyzed. [ABSTRACT FROM AUTHOR]

Photocatalytic materials are of great scientific interest due to their potential applications in sustainable energy sources. Band gap and optical absorption of the materials are two core characteristics for photocatalysis that eventually depend on electronic structure. In order to accurately compute (predict) the electronic‐scale properties of a crystalline solid using first principles calculations, which might be costly to measure experimentally, large‐scale atomic level calculation frameworks have been made possible through the use of density functional theory (DFT). We have used DFT with many body perturbation theory (MBPT) by solving the bethe‐salpeter equation (BSE) to priorly predict the properties of bulk tin sulfide (SnS) as it meets the necessary requirements for photocatalytic applications. We fixed the DFT band gap underestimation by including the Hubbard parameter (U) and used projector augmented wave pseudo‐potentials with generalized‐gradient approximation (GGA) to calculate the electronic and optical properties of SnS. Optical properties were computed using independent particle approximation (IPA) and BSE with DFT+U wave functions. Our theoretical results align with experimental data for this material, demonstrating the potential for further research in validating experimental results with theoretical approximations and empirical relations. [ABSTRACT FROM AUTHOR]

We have identified a complex interplay of van der Waals, coulombic, and direct edge-to-edge covalent interactions as key factors in determining the stability of bilayer zigzag SiC nanoribbons (ZSiCNRs). The Si–Si edge of the homo-AA-stacked ZSiCNR displays a unique bond angle, indicative of sp 3-like covalent bonds. In contrast, the C–C edge shows a flat structure, suggesting a formation of the pseudo-chemical bonding between p z orbitals at the edge like bilayer graphene NRs. The homo-AA-stacked ZSiCNR is nonmagnetic and metallic, although the monolayer ZSiCNR exhibits magnetic properties due to spin-polarized p z orbitals localized at the edge Si and C atoms. In contrast, the hetero-AA-stacked ZSiCNR is more stable than the homo one and is indicative of semiconductor properties with a finite band gap, since the topology of the edge states originating from p z orbitals is no longer preserved. [ABSTRACT FROM AUTHOR]

To investigate the dissolution mechanism of Ti metal, ab initio calculations were conducted to observe the impact of Ti vacancy defects on the O-adsorbed Ti(0001) surface, focusing on the formation energies of Ti vacancy, geometric structures, and electronic structures. The surface structures subsequent to Ti dissolution were simulated by introducing a Ti cavity on both clean and O-adsorbed Ti(0001) surfaces. Our findings indicated that Ti vacancy formation energies and electrochemical dissolution potential on the O-adsorbed Ti(0001) surface surpassed those on the clean surface, and they increased with increasing O coverage. This suggested that O adsorption inhibited Ti dissolution and enhanced O atom interaction with the Ti surface as O coverage increased. Furthermore, at higher O coverage, Ti vacancies contributed to the strengthening of Ti-O bonds on the O-adsorbed Ti(0001) surface, indicating that Ti dissolution aided in stabilizing the Ti surface. The formation of Ti vacancies brought the atomic ratio of Ti to O on the Ti surface closer to that of TiO2, potentially explaining the increased stability of the structure with Ti vacancies. [ABSTRACT FROM AUTHOR]

In order to design Cu-Sn alloys with excellent overall performance, the structural stability, mechanical properties, and electronic structure of X-doped Cu-Sn alloys were systematically calculated using first-principles calculations. The calculation results of the cohesive energy indicate that the Cu-Sn-X structures formed by X atoms (X = Ag, Ca, Cd, Mg, Ni, Zr) doping into Cu-Sn can stably exist. The Cu-Sn-Ni structure is the most stable, with a cohesive energy value of −3.84 eV. Doping of X atoms leads to a decrease in the bulk modulus, Possion's ratio and B/G ratio. However, doping Ag and Ni atoms can improve the shear modulus, Young's modulus, and strain energy of the dislocation. The doping of Ni has the highest enhancement on shear modulus, Young's modulus, and strain energy of the dislocation, with respective values as follows: 63.085 GPa, 163.593 GPa, and 1.689 W/J· m − 1 . The analysis of electronic structure results shows that the covalent bond between Cu and X is the reason for the performance differences in Cu-Sn-X structures. [ABSTRACT FROM AUTHOR]

To explore the stability, electrical, and mechanical characteristics of undoped AgNi alongside AgNi doped with elemental Ge, V, and Ta, we performed calculations on their electronic structures using density functional theory from first-principles. We also prepared AgNi(17) and AgNi-x(Ge, V, Ta) electrical contact materials using the powder metallurgy technique, and they were subsequently assessed experimentally. The electrical properties of these materials were evaluated under a 24 V/15 A DC-resistive load using the JF04D contact material testing system. A three-dimensional morphology scanner was employed to examine the contact surface and investigate the erosion patterns of the materials. Our findings indicate that doping with metal elements significantly enhanced the mechanical properties of electrical contacts, including conductivity and hardness, and optimizes arc parameters while improving resistance to arc erosion. Notably, AgNi-Ge demonstrated superior conductivity and arc erosion resistance, showing significant improvements over the undoped AgNi contacts. This research provides a theoretical foundation for selecting doping elements aimed at enhancing the performance of AgNi electrical contact materials. [ABSTRACT FROM AUTHOR]

The impact of variations in the content of single alloying element on the properties of alloy materials has been extensively discussed, but the influence of this change on the content of multiple alloying elements in the alloy materials has been disregarded, as the performances of alloy materials should be determined by the collective influence of multiple alloying elements. To address the aforementioned issue, the present study conducted a comprehensive investigation into the impact of variations in the content of alloying elements, namely Ni, Cr, and Co, on the structural and mechanical properties of L12-(Nix1Crx2Cox3)3Al precipitates using the high-throughput first-principles calculations and the partial least squares (PLS) regression, and the competitive mechanism among these three elements was elucidated. The findings demonstrate that the same alloying element may exhibit opposite effects in both single element analysis and comprehensive multi-element analysis, for example, the effect of Ni element on elastic constant C11, and the influence of Cr element on Vickers hardness and yield strength. The reason for this is that the impact of the content of other two alloying elements is ignored in the single element analysis. Meanwhile, the Co element demonstrates a significant competitive advantage in the comparative analysis of three alloying elements for different physical properties. Therefore, the methodology proposed in this study will facilitate the elucidation of competition mechanisms among different alloy elements and offer a more robust guidance for experimental preparation. [ABSTRACT FROM AUTHOR]

Layered‐type transition metal (TM) oxides are considered as one of the most promising cathodes for K‐ion batteries because of the large theoretical gravimetric capacity by low molar mass. However, they suffer from severe structural change by de/intercalation and diffusion of K+ ions with large ionic size, which results in not only much lower reversible capacity than the theoretical capacity but also poor power capability. Thus, it is important to enhance the structural stability of the layered‐type TM oxides for outstanding electrochemical behaviors under the K‐ion battery system. Herein, it is investigated that the substitution of the appropriate Ti4+ contents enables a highly enlarged reversible capacity of P3‐type KxCrO2 using combined studies of first‐principles calculation and various experiments. Whereas the pristine P3‐type KxCrO2 just exhibits the reversible capacity of ∼120 mAh g−1 in the voltage range of 1.5–4.0 V (vs. K+/K), the ∼0.61 mol K+ corresponding to ∼150 mAh g−1 can be reversible de/intercalated at the structure of P3‐type K0.71[Cr0.75Ti0.25]O2 under the same conditions. Furthermore, even at the high current density of 788 mA g−1, the specific capacity of P3‐type K0.71[Cr0.75Ti0.25]O2 is ∼120 mAh g−1, which is ∼81 times larger than that of the pristine P3‐type KxCrO2. It is believed that this research can provide an effective strategy to improve the electrochemical performances of the cathode materials suffered by severe structural change that occurred during charge/discharge under not only K‐ion battery system but also other rechargeable battery systems. [ABSTRACT FROM AUTHOR]

The 2D ferrovalley semiconductor (FVSC) with spontaneous valley polarization offers an exciting material platform for probing Berry phase physics. How FVSC can be incorporated in valleytronic device applications, however, remain an open question. Here, the concept of metal/semiconductor (MS) contact into the realm of valleytronics is generalized. A half‐valley Ohmic contact is proposed based on FVSC/graphene heterostructure, where the two valleys of FVSC separately forms Ohmic and Schottky contacts with those of graphene, thus allowing current to be valley‐selectively injected through the 'Ohmic' valley while being blocked in the 'Schottky' valley. A theory of contact‐limited valley‐contrasting current injection is developed and such transport mechanism can produce gate‐tunable valley‐polarized injection current. Using RuCl2/graphene heterostructure as an example, a device concept of valleytronic barristor is illustrated, where high valley polarization efficiency and sizable current on/off ratio, can be achieved under experimentally feasible electrostatic gating conditions. These findings uncover contact‐limited valley‐contrasting current injection as an efficient mechanism for valley polarization manipulation, and reveals the potential of valleytronic MS contact as a functional building block of valleytronic device technology. [ABSTRACT FROM AUTHOR]

Isovalent doping offers a method to enhance the thermoelectric properties of semiconductors, yet its influence on the phonon structure and propagation is often overlooked. Here, we take C d X ( X = T e ,   S e ) compounds as an example to study the role of isovalent doping in thermoelectrics by first-principles calculations in combination with the Boltzmann transport theory. The electronic and phononic properties of C d 8 S e 8 , C d 8 S e 7 T e , C d 8 T e 8 , and C d 8 T e 7 S e are compared. The results suggest that isovalent doping with C d X significantly improves the thermoelectric performance. Due to the similar properties of S e and T e atoms, the electronic properties remain unaffected. Moreover, doping enhances anharmonic phonon scattering, leading to a reduction in lattice thermal conductivity. Our results show that optimized p-type(n-type) ZT values can reach 3.13 (1.33) and 2.51 (1.21) for C d 8 T e 7 S e and C d 8 S e 7 T e at 900 K, respectively. This research illuminates the potential benefits of strategically employing isovalent doping to enhance the thermoelectric properties of C d X compounds. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries with a high theoretical energy density of 2600 Wh·kg−1 are hindered by challenges such as low S conductivity, the polysulfide shuttle effect, low S reduction conversion rate, and sluggish Li2S oxidation kinetics. Herein, single-atom non-noble metal catalysts (SACs) loaded on two-dimensional (2D) vanadium disulfide (VS2) as the potential host materials for the cathode in Li–S batteries were investigated systematically by using first-principles calculations. Based on the comparisons of structural stability, the ability to immobilize sulfur, electrochemical reactivity, and the kinetics of Li2S oxidation decomposition between these non-noble metal catalysts and noble metal candidates, Nb@VS2 and Ta@VS2 were identified as the potential candidates of SACs with the decomposition energy barriers for Li2S of 0.395 eV (Nb@VS2) and of 0.162 eV (Ta@VS2), respectively. This study also identified an exothermic reaction for Nb@VS2 and the Gibbs free energy of 0.218 eV for Ta@VS2. Furthermore, the adsorption and catalytic mechanisms of the VS2-based SACs in the reactions were elucidated, presenting a universal case demonstrating the use of unconventional graphene-based SACs in Li–S batteries. This study presents a universal surface regulation strategy for transition metal dichalcogenides to enhance their performance as host materials in Li–S batteries. [ABSTRACT FROM AUTHOR]

Utilizing first-principles calculations about A-B-O binary systems (A = Zr, Hf; B = Ta, Nb) and oxyacetylene ablation tests (2.4 MW/m2, 30 s), the synergistic effects of Hf, Zr, Ta and Nb elements in (Hf-Zr-Ta-Nb)C ceramic were studied. From the aspect of experimental results, the (Hf-Zr-Ta-Nb)C ceramic exhibited the lowest average linear variation rate (−1.2 μm/s) and thinnest oxide layer (∼170 μm), only half the thickness of (Hf–Ta)C ceramic (∼330 μm). From the aspect of protective characteristic of HfO 2 -based oxide layer, Ta enrichment will be easier to bring about structural instability of HfO 2 than Zr and Nb elements, attributed to the easily formed Hf 6 Ta 2 O 17 phase with relatively low melting point. As for ZrO 2 -based solid solutions, the continuous enrichment of Ta and Nb will both cause structural instability, based on the increasing trend of calculated binding energies of Ta or Nb modified ZrO 2 , accompanied by the spontaneous formation trend of Zr 6 Ta 2 O 17 and Zr 6 Nb 2 O 17 low-melting-point phases. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) Janus structures, as a newly derived form of 2D materials, have recently attracted great attention due to their structural symmetry breaking along with a piezoelectric effect and potential applications in nanoscale sensors, surface acoustic waves, and energy harvesters. To date, 2D Janus materials mainly appear in the IV–VI and III–V systems but are scarce involving the IV–V elements. Hereby, utilizing first-principles structure prediction, a stable IV–V–V family of 2D Janus structure 1T-M2AB (M = Si, Ge, Sn, A/B = N, P, As) was proposed. Their electronic, elastic, and piezoelectric properties are systematically investigated and compared. The calculated piezoelectric coefficient results reveal that the 1T-Sn2NP exhibits superior piezoelectric performance with a high in-plane piezoelectric constant (−8.07 pm/V), beyond many known 2D piezoelectric materials. Three independent factors of charge density distribution, vertical mirror asymmetry, and electrostatic potential gradients were assessed, which can well account for the piezoelectric characteristics of 1T-M2AB. This work not only demonstrates the potential applications of 2D Janus 1T-M2AB monolayer in piezoelectric devices but also enriches the family of 2D Janus structures. [ABSTRACT FROM AUTHOR]

Renowned for their outstanding structural and electronic properties, two-dimensional (2D) polar materials are highly regarded as promising candidates for advanced optoelectronics and catalysis applications. Herein, based on the design principle of valence charge balance and layer stacking, we successfully designed 22 stable 2D polar monolayers with intrinsic built-in electric fields. The predicted monolayer, i.e., 2D MAN3, originates from the MA2N4 (M= V, Nb, Ta; A = Si, Ge) and has been widely studied in recent years. All of these monolayers exhibit semiconductor properties, with half displaying a direct band feature. Additionally, 2D MAN3 monolayer shows remarkable hole mobility (∼104 cm2 V–1 s–1) and optical absorption. Furthermore, the band edges of these monolayers not only facilitate the establishment of diverse interface contacts but also meet the requirements for photovoltaic water splitting. Our work not only significantly expands the MAN3 family but also provides valuable insights for its future research on optoelectronic applications. [ABSTRACT FROM AUTHOR]

MXenes have superior catalytic activities, because of their excellent electronic properties. In this work, the electronic properties, quantum capacitance, and photocatalytic activity of Pt-doped Zr2CO2 (Pt-VO-Zr2CO2) nanosheets under biaxial strain are investigated by first-principles calculations. Pt-VO-Zr2CO2 are all indirect semiconductors under compressive strain and are direct semiconductors under tensile strain except at 10%. The red shift of Zr-d and O-p orbitals in conduction bands results in the decrease of band gaps under compressive strain. Pt-VO-Zr2CO2 under strain except at −8% are cathode materials in an aqueous system, especially for Pt-VO-Zr2CO2 with +10% strain with the maximum storage charge. Pt-VO-Zr2CO2 under strain can reduce water at pH 0 and perform overall water splitting in a neutral environment. Pt-VO-Zr2CO2 nanosheets with a strain larger than +4% can reduce CO2 to all products, and tensile strain enhances CO2 photocatalysis. The N2 reduction capability of Pt-VO-Zr2CO2 reduces in a neutral environment. [ABSTRACT FROM AUTHOR]

Developing highly active metal-based single-atom catalysts (SACs), as a thriving topic in overall water-splitting, can maximum atom utilization efficiency and yet entail high activity, and bifunctional hydrogen evolution reaction (HER)/oxygen evolution reaction (OER) electrocatalysts can enable more efficient overall water-splitting meanwhile reducing the cost than two individual unifunctional electrocatalysts. Bifunctional HER/OER SACs are thus of enormous economic importance and scientific interest. Herein, using density functional theory (DFT) calculations, a design of the optimal bifunctional SACs was achieved, namely, C 30 N 12 Se 6 H 12 supported Rh (Rh@CNSeH). Also worth noting is that Rh@CNSeH stands out among 23 candidates and holds the promise of as an efficient bifunctional catalyst due to low HER/OER overpotential of 0.003/0.39 V, outperforming the commercial Pt (0.09 V)/IrO 2 (0.55 V) and achieving the overall water-splitting. Good stability demonstrated by calculations of ab initio molecular dynamics simulation, antioxidant capacity and Pourbaix diagram ensured the implementation of Rh@CNSeH in ambient conditions. Remarkably, Δ G O H * can act as an energy descriptor to reveal and even predict the OER activity trend, whose changing trend can be quantitatively described by charge transfer descriptor (Bader charge analysis) and electronic structure descriptors (d-band center and integrated crystal orbital Hamilton population (ICOHP)). Moreover, an intrinsic descriptor (φ) coupled with the electronegativity and the d-electrons number of transition-metal can give a reasonable prediction and explanation for the catalytic activity origin. Finally, we built a bridge for structure-property relationship from intrinsic characteristics to Bader charge, to d-band center, to ICOHP and then to free energies of intermediates, which can intuitively herald the activity origin of OER and give a reasonable guidance toward high-efficient designing for SACs. • Developing highly active metal-based single-atom catalysts (SACs). • Screening Rh@CNSeH as bifunctional water-splitting catalyst. • Finding descriptors to reveal and even predict the electrocatalytic activity trend. • An intrinsic descriptor can give a reasonable explanation for the activity origin. • Bridge from basic properties to descriptors can give a guidance for design of SACs. [ABSTRACT FROM AUTHOR]

We have used density functional theory simulations to explore the topological characteristics of a new MXene‐like material, V4C3, and its oxide counterpart, assessing their potential as anode materials for Mg‐ion batteries. Our research reveals that V4C3 monolayer is a topological type‐II nodal line semimetal, protected by time reversal and spatial inversion symmetries. This type‐II nodal line is marked by unique drumhead‐like edge states that appear either inside or outside the loop circle, contingent upon the edge ending. Intriguingly, even with an increase in metallicity due to oxygen functionalization, the topological features of V4C3 remain intact. Consequently, the monolayer V4C3 has a topologically enhanced electrical conductivity that amplifies further upon oxygen functionalization. During the charging phase, a remarkable storage concentration led to a peak specific capacity of 894.73 mAh g−1 for V4C3, which only decreases to 789.33 mAh g−1 for V4C3O2. When compared to V2C, V4C3 displays a significantly lower specific capacity loss due to functionalization, demonstrating its superior electrochemical properties. Additionally, V4C3 and V4C3O2 exhibit moderate average open‐circuit voltages (0.54 V for V4C3 and 0.58 V for V4C3O2) and energy barriers for intercalation migration (ranging between 0.29–0.63 eV), which are desirable for anode materials. Thus, our simulation results support V4C3 potential as an efficient anode material for Mg‐ion batteries. [ABSTRACT FROM AUTHOR]

In this study, we conducted an extensive investigation into broadband near-infrared luminescence of Cr3+-doped Ca3Y2Ge3O12 garnet, employing first-principles calculations within the density functional theory framework. Our initial focus involved determining the site occupancy of Cr3+ activator ions, which revealed a pronounced preference for the Y3+ sites over the Ca2+ and Ge4+ sites, as evidenced by the formation energy calculations. Subsequently, the geometric structures of the excited states 2E and 4T2, along with their optical transition energies relative to the ground state 4A2 in Ca3Y2Ge3O12:Cr3+, were successfully modeled using the ΔSCF method. Calculation convergence challenges were effectively addressed through the proposed fractional particle occupancy schemes. The constructed host-referred binding energy diagram provided a clear description of the luminescence kinetics process in the garnet, which explained the high quantum efficiency of emission. Furthermore, the accurate prediction of thermal excitation energy yielded insights into the thermal stability of the compound, as illustrated in the calculated configuration coordinate diagram. More importantly, all calculated data were consistently aligned with the experimental results. This research not only advances our understanding of the intricate interplay between geometric and electronic structures, optical properties, and thermal behavior in Cr3+-doped garnets but also lays the groundwork for future breakthroughs in the high-throughput design and optimization of luminescent performance and thermal stability in Cr3+-doped phosphors. [ABSTRACT FROM AUTHOR]

The low index interfacial configuration, interface energy and electronic properties of NbC/α-Fe are calculated using the first-principles method based on density functional theory and ab initio molecular dynamics simulation. Additionally, the NbC/α-Fe interface with the low index interfacial configuration is calculated by two-dimensional disregistry method. It is demonstrated that the Fe-C type has an interface energy of -1.553 J/m², the smallest interface energy and the most stable structure, therefore the Fe-C type is the most stable conformation of the NbC(001)/α-Fe(001). Strong orbital resonance phenomenon exists between Fe-3d, Nb-4d and C-2p, producing strong metallic and covalent bonds. The results of disregistry calculation by different interfacial structures of NbC/α-Fe shows that the disregistry of NbC(001)/α-Fe(001) crystalline surface is the smallest at 10.19%, which corresponds to the results of interface energy calculation. It can be shown that the α-Fe(001) is the optimal orientation surface of the NbC(001). Herein, we have revealed the site-oriented and stable bonding mode relationship of NbC/α-Fe interface in steel, which provides important theoretical guidance to explore the mechanism of grain refinement of NbC particles in shipbuilding steels. [ABSTRACT FROM AUTHOR]

Although hydrides such as LaH10 are experimentally confirmed to possess high superconducting critical temperature (Tc) of 250-260 K under 170-200 GPa, it is still a tough challenge to be applied. It is highly anticipated to find hydride superconductors with relatively high Tc at low or ambient pressure. Reducing the dimensionality of materials can induce unexpected properties that are distinct from their bulk counterparts, and whether it can modulate the superconducting properties deserves further investigation. Herein, a new 2D monolayer aluminum hydride h-AlH2 is theoretically predicted under ambient pressure based on the first-principles calculations. Since the electronic structures of h-AlH2 reveal the metallicity, the electron-phonon coupling (EPC) and possible phonon-mediated superconductivity are investigated. Based on the isotropic Eliashberg equation, the calculated EPC constant λ of h-AlH2 is 1.16, and the Tc is up to 42.6 K. The EPC mainly originates from the coupling between electrons of Al-s, px, py, and H-s orbitals and the in-plane vibration modes of H atoms. Especially, the Tc can be enhanced to 63.7 K by applying 3% biaxial tensile strain. Thus, the predicted h-AlH2 provides a new platform for finding hydride superconductors in lowdimensional materials at ambient pressure. [ABSTRACT FROM AUTHOR]

The topological effects of phonons are extensively studied in various materials, which have the potential to improve heat dissipation in power electronics due to its intrinsic, topologically protected, nondissipative phonon surface states. Nevertheless, the phase transition of the Weyl phonons in nitrides is yet to be elucidated. To unveil the microscale origin, topological phonon properties in AlGaN alloys are investigated from first principles. It is found that phase transitions in Weyl phonons are evidently present in AlGaN alloys and nitride single crystals. Under strain states, both GaN and AlN show a more prominent phase transition of Weyl phonons when subjected to biaxial compressive and uniaxial tensile strains. It has been observed that the zz components in the self-term and the transverse first-nearest-neighbor (1NN) force constants (FCs) are the most influential. The noncontinuous Weyl phonon phase transition in AlGaN alloys is reflected in the normalized self-term and 1NN FCs, which vary in a nonlinear fashion with increasing magnitude. With increased branches in AlGaN alloys, hundreds of Weyl phonons are present accompanied by significant disorders in normalized FCs, which mainly occur for N atoms in self-terms and for all components in normalized 1NN FCs. [ABSTRACT FROM AUTHOR]

The retention of the photoactive phase is vital for inorganic CsPbI3 perovskite solar cells; however, the atomic‐level knowledge is currently elusive, leading to trial‐and‐error methods in experiments. In this study, proves that the kinetic process dominates the lifetime of CsPbI3, while the energetic difference, which is conventionally thought to be a dominant factor, only plays a secondary role. The defect—iodine vacancy (VI) can significantly lower the kinetic barriers and act as the seed of structural collapse in the corner‐sharing octahedral structure. Inspired by this, the success of B‐ and X‐site doping as well as strain engineering for stabilizing CsPbI3 arising from the suppression of VI are explained. Through comprehensively investigating thirty‐two and fifteen kinds of passivators substituting on the Pb and I site, respectively, on reducing the VI concentration and inhibiting its diffusion, proposed that the trivalent lanthanide cations, especially La3+ on Pb site, and highly electronegative anions with a small size on I site are proper doping candidates to enhance the stability of perovskite CsPbI3. The results provide a universal picture and guidance for engineering all‐inorganic perovskite CsPbI3 for elevated stability with the focus on inhibiting iodine vacancies. [ABSTRACT FROM AUTHOR]

Hydrogen-based compounds have been found to exhibit high superconducting critical temperature ( T c ) through the electron–phonon coupling mechanism under ultrahigh pressure. Herein, a new two-dimensional transition metal dichalcogenide material is constructed, namely, the Janus WSH monolayer. It is formed by replacing one layer of S atoms in the WS2 monolayer with H atoms. Then the electronic structure, phonon dispersion, electron–phonon coupling, and superconductivity are investigated by first-principles calculations. The results show that the introduction of H atoms helps to flatten the electronic dispersion and leads to high electronic density of states at the Fermi level, resulting in strong electron–phonon coupling. Additionally, the softening of phonon modes from the hybridization of in-plane W atomic vibrations and out-of-plane H atomic vibrations boosts the electron–phonon coupling further. The strong interactions between electrons and phonons lead to phonon-mediated superconductivity in Janus WSH monolayer with a calculated T c being about 23.1 K. This is the highest T c predicted in WS2-based materials at present, which indicates that hydrogenation is a great way to improve the T c of transition metal dichalcogenide materials. [ABSTRACT FROM AUTHOR]

In recent years, studies on the two-dimensional transition metal dichalcogenides have become important since their potentials have useful properties in technological applications. In this respect, the structural, electronic and vibrational properties of the 12 transition metal dichalcogenide (TMD) MX2 (M=Mo,W,Cr,Ni; X=S,Se,Te) sheets are investigated using first-principles calculations. The calculated band structures show that all TMDs are semiconductors with a direct band gap at the K point, except NiX2 ones with indirect band gaps. We find energetic and dynamical stabilities of the MX2 sheets, while NiSe2 lattice becomes unstable with negative frequencies appearing in acoustic modes near the K point. We also discuss the role of average atomic mass and interatomic bonding in determining the Debye temperatures of dynamically stable dichalcogenide sheets. [ABSTRACT FROM AUTHOR]

In this work, novel monolayers of 2D Janus SHfAZ2 (A═Si, Ge; Z═N, P, As) materials are introduced. These Janus structures are primarily investigated for their ability to exhibit adjustable electronic properties when subjected to biaxial strain and an applied electric field. At equilibrium, the four structures in the Janus SHfAZ2 monolayers all display indirect bandgap semiconductor properties, with the exception of the SHfGeN2 monolayer, which exhibits direct bandgap semiconductor properties. Under the influence of biaxial strain, the study observes that the electronic properties of all SHfAZ2 monolayers can be adjusted, transitioning from semiconductor to metallic properties when subjected to compressive strain. However, the SHfSiP2, SHfGeP2, and SHfGeAs2 monolayers show limited sensitivity to an applied electric field, with their electronic properties being modifiable solely under the influence of applied biaxial strain. In contrast, both the SHfSiAs2 and SHfGeN2 monolayers demonstrate the ability to modulate their electronic properties from semiconductors to metals when subjected to both biaxial strain and an applied electric field. Finally, the carrier mobility of these five structures is calculated. The outcomes of the research provide a solid theoretical foundation for the potential utilization of 2D Janus SHfAZ2 monolayers in electronic devices. [ABSTRACT FROM AUTHOR]

Hydrogen as a sustainable and clean energy source has been widely noticed, but it is urgent to find an efficient and stable electrocatalyst to increase its hydrogen production. For the catalytic performance of electrocatalysts, defects, doping, and stress are usually selected to enhance the catalytic performance, on the basis of which in this paper, MSi 2 N 4 (M = Mo, W) system containing vacancies and bimetallic doping was constructed and analyzed for its HER performance. The results show that the formation energy of all structures is stable and Ni doping can significantly improve the stability according to formation energy of the structures with vacancy. Both ipsilateral doping and contralateral doping can significantly improve the Gibbs free energy of MA 2 Z 4 materials, especially the MoSi 2 N 4 doped with double Co. In particular, the values of Gibbs free energy of C-Ni-V N @MoSi 2 N 4 -N in and C-Co-V N @WSi 2 N 4 -N in are −0.027 eV and 0.041 eV, significantly better than the performance of the recognized electrocatalyst Pt, which has a free energy of only 0.09 eV. After doped with transition metallic atoms, the energy bands of all materials present semiconductor property. Our work provides a novel method for the regulation of MA 2 Z 4 family materials and a theoretical strategy for designing efficient HER electrocatalysts. • Screening of bimetal-doped MA 2 Z 4 with defective structures for HER catalytic activity. • The HER performance of the ipsilateral doping is better than that of the contralateral doping. • The vacancies can significantly improve the formation energy of Ni doped materials. • The MoSi 2 N 4 defect structure doped with double Co has a near-zero ΔG H. [ABSTRACT FROM AUTHOR]

The relatively low melting point of a traditional Si bonding layer limits the upper servicing temperature of environmental barrier coatings (EBC). To explore suitable high temperature bonding layers and expedite the development of EBC, first-principles calculation was used to evaluate the mechanical properties and thermal conductivity of HfSi2, HfSi, Hf5Si4, Hf3Si2, and Hf2Si with much higher melting points than that of Si. Among them, HfSi2 has the lowest modulus capable of good modulus matching with SiC substrate. In addition, these Hf-Si compounds have much lower high temperature thermal conductivity with Hf2Si being the lowest of 0.63 W m−1 K−1, which is only half of Si, capable of improved heat insulation. [ABSTRACT FROM AUTHOR]

In this work, we have performed extensive swarm-intelligence structures searching simulations on the RbBSi compounds within the pressure range from 0 to 100 GPa. We have proposed three different phases of RbBSi, of which the stability, the electronic structure and the potential superconductivity were calculated by first-principles calculations. All predicted phases are thermodynamically and dynamically stable within the studied pressure range. The bands of the three phases crossing the Fermi level indicate the structures are all metallic. In addition, P4/nmm-RbBSi is a superconductor with Tc of 14.4 K at ambient pressure. This work extends the understanding and potential application of alkali metal boron-silicide compounds in the field of superconductor. [ABSTRACT FROM AUTHOR]

Near-infrared laser radiation based on Nd3+-doped yttrium ortho-aluminate (Nd:YAlO3, Nd:YAP) has garnered significant interest regarding solid-state lasers. Nevertheless, the crystal microstructures and electronic characteristics of Nd:YAP are still unclear, and the unique physical properties underlying its enormous applications require clarification. In this study, we conducted first-principles calculations at the atomic level to explore the electronic properties and mechanical characteristics of both pure YAP and Nd3+-doped YAP. The results suggest that the substitution of the Y3+ ion site with the Nd3+ impurity ion induces slight structural distortion in the YAP crystal lattice. An impurity band emerges between the original conduction band and the valence band, attributed to the 4f orbital of the Nd3+ ion, exerting a substantial influence on the narrowing of the band gap. Through an analysis of the mechanical characteristics of both pure YAP and Nd:YAP, we conclude that the incorporation of Nd3+ atoms leads to a reduction in the mechanical properties of YAP to a certain extent. Our study can serve as a foundational data source for investigations into material performance, especially for the application of Nd:YAP in solid-state laser systems. [ABSTRACT FROM AUTHOR]

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Negative thermal expansion (NTE) is crucial for controlling the thermomechanical properties of functional materials, albeit being relatively rare. This study reports a giant NTE (αV∼−9.2 ⋅ 10−5 K−1, 100–200 K; αV∼−3.7 ⋅ 10−5 K−1, 200–650 K) observed in NaB(CN)4, showcasing interesting ultralight properties. A comprehensive investigation involving synchrotron X‐ray diffraction, Raman spectroscopy, and first‐principles calculations has been conducted to explore the thermal expansion mechanism. The findings indicate that the low‐frequency phonon modes play a primary role in NTE, and non‐rigid vibration modes with most negative Grüneisen parameters are the key contributing factor to the giant NTE observed in NaB(CN)4. This work presents a new material with giant NTE and ultralight mass density, providing insights for the understanding and design of novel NTE materials. [ABSTRACT FROM AUTHOR]

Negative thermal expansion (NTE) is crucial for controlling the thermomechanical properties of functional materials, albeit being relatively rare. This study reports a giant NTE (αV∼−9.2 ⋅ 10−5 K−1, 100–200 K; αV∼−3.7 ⋅ 10−5 K−1, 200–650 K) observed in NaB(CN)4, showcasing interesting ultralight properties. A comprehensive investigation involving synchrotron X‐ray diffraction, Raman spectroscopy, and first‐principles calculations has been conducted to explore the thermal expansion mechanism. The findings indicate that the low‐frequency phonon modes play a primary role in NTE, and non‐rigid vibration modes with most negative Grüneisen parameters are the key contributing factor to the giant NTE observed in NaB(CN)4. This work presents a new material with giant NTE and ultralight mass density, providing insights for the understanding and design of novel NTE materials. [ABSTRACT FROM AUTHOR]

Herein, a first-principles pseudopotential plane-wave method is used to investigate the effects of co-doping Sc with Cu (or Zn) on the structural stability and desorption temperature of Mg-based hydrogen storage alloys and their hydride phases, as well as the related microscopic mechanisms. Specifically, the cell volume, electronic density of states, bond order, differential charge density, charge spreading, enthalpy of generation, and hydrogen desorption temperature of Mg 1.75 Sc 0.25 Ni 1−x M x H 4 (M = Cu or Zn, x = 0.125, 0.25, 0.375, and 0.5) are analyzed. Results indicate that the Mg 2 Ni alloy cell expands with an increase in the concentration of Cu or Zn co-doped with Sc. This expansion avoids the formation of a hydrogen adsorption layer, thus facilitating the entry and exit of hydrogen atoms from the alloy, thus improving its hydrogen release performance. In addition, the Cu or Zn atoms attract the surrounding H atoms and weaken the H–Ni bonds. Thus, the stability and dehydrogenation temperature of the system decrease with increasing Cu or Zn content. [Display omitted] • First-principles pseudopotential plane-wave method used to investigate Mg-based hydrogen storage materials. • The cell volume of the Mg 2 Ni alloy increases with increasing dopant content. • Co-doping Sc and M (M: Cu or Zn) in Mg 2 Ni weakens the bonding order of the H–Mg and H–Ni bonds. • Sc and M co-doping in Mg 2 Ni improves hydrogen release from the hydride phase. [ABSTRACT FROM AUTHOR]

Hydrogen is a promising clean energy source to address the energy issue as well as the environmental and health risks of current energy sources. Metal hydrides have demonstrated significant potential for storing hydrogen. The perovskite hydrides AMgH 3 (A = Be, Ca) have demonstrated potential for hydrogen storage applications due to their impressive gravimetric hydrogen density of 8.32 and 4.49 wt% for BeMgH 3 and CaMgH 3 , respectively. The calculated results indicate that AMgH 3 (A = Be, Ca) perovskite hydrides exhibit metallic character. The AMgH 3 (A = Be, Ca) compounds mostly absorb quanta of energy in the IR range, but they also exhibit high absorption in the UV region. The formation enthalpies of these hydrides have been found to be negative, indicating that they are thermodynamically stable. Furthermore, it has been established that these perovskite hydrides are mechanically stable as they fulfil Born stability criteria. [Display omitted] • Hydrogen storage properties of AMgH 3 (A = Be, Ca) are investigated using DFT approach. • AMgH 3 (A = Be, Ca) show metallic character as their energy bandgap value is 0 eV. • They show remarkable gravimetric H-densities of 8.32 and 4.49 wt%. • AMgH 3 (A = Be, Ca) perovskite hydrides exhibit thermodynamic and mechanical stability. [ABSTRACT FROM AUTHOR]

Negative thermal expansion (NTE) is crucial for controlling the thermomechanical properties of functional materials, albeit being relatively rare. This study reports a giant NTE (αV∼−9.2 ⋅ 10−5 K−1, 100–200 K; αV∼−3.7 ⋅ 10−5 K−1, 200–650 K) observed in NaB(CN)4, showcasing interesting ultralight properties. A comprehensive investigation involving synchrotron X‐ray diffraction, Raman spectroscopy, and first‐principles calculations has been conducted to explore the thermal expansion mechanism. The findings indicate that the low‐frequency phonon modes play a primary role in NTE, and non‐rigid vibration modes with most negative Grüneisen parameters are the key contributing factor to the giant NTE observed in NaB(CN)4. This work presents a new material with giant NTE and ultralight mass density, providing insights for the understanding and design of novel NTE materials. [ABSTRACT FROM AUTHOR]

Negative thermal expansion (NTE) is crucial for controlling the thermomechanical properties of functional materials, albeit being relatively rare. This study reports a giant NTE (αV∼−9.2 ⋅ 10−5 K−1, 100–200 K; αV∼−3.7 ⋅ 10−5 K−1, 200–650 K) observed in NaB(CN)4, showcasing interesting ultralight properties. A comprehensive investigation involving synchrotron X‐ray diffraction, Raman spectroscopy, and first‐principles calculations has been conducted to explore the thermal expansion mechanism. The findings indicate that the low‐frequency phonon modes play a primary role in NTE, and non‐rigid vibration modes with most negative Grüneisen parameters are the key contributing factor to the giant NTE observed in NaB(CN)4. This work presents a new material with giant NTE and ultralight mass density, providing insights for the understanding and design of novel NTE materials. [ABSTRACT FROM AUTHOR]

Ferrovalley (FV) materials with high performance have attracted significant attention for their potential applications in information storage and logic operations. In this report, the RuOHCl monolayer with a 1H phase structure is found to be a ferromagnetic semiconductor by first-principles calculations. RuOHCl monolayer presents an in-plane magnetic anisotropy with a critical temperature of magnetic phase transition up to 461 K. Moreover, RuOHCl monolayer exhibits FV characteristics with a valley polarization up to 201 meV. Interestingly, the magnetic, electronic, and valley properties of the RuOHCl monolayer can be effectively regulated using biaxial strain. Under compressive strains, the RuOHCl monolayer keeps the FV state, and its easy axis of magnetization can be turned from in-plane to out-of-plane, induced by the change in the d-orbitals interactions of the Ru atom. With the action of tensile strains, the RuOHCl monolayer can achieve mutual transformation between FV, half-valley metal, and quantum anomalous Hall effect, resulting in a topological transition is achieved. Finally, anomalous valley Hall devices by doping holes and electrons into the RuOHCl monolayer are proposed. This study indicates that the RuOHCl monolayer is one of the amazing materials for the development of spintronics and valleytronics devices. [ABSTRACT FROM AUTHOR]

A data‐driven understanding of the reaction mechanism of the O3‐type Na[Li1/3Mn2/3]O2‐layered cathode model is systematically performed to decouple the complex correlations of covariate scale‐dependent variables in diagnosing and solving structural problems for facilitating nonhysteretic and reversible (nHR) oxygen capacities using interpretable machine learning (ML) assisted by density functional theory. A large dataset of vacancy formation energies depending on the desodiation mode for the oxide is investigated in detail, and it provides two numerical principles: i) linearizing the energy landscape and ii) steepening its slope to reach the ideal reaction. The heatmaps comprising Pearson coefficient correlation values are broken down into two‐scale components: i) macroscopic and ii) local structure features. Deriving the overall mitigation of scale‐dependent covariate variables in negative correlation potentially leads to nHR anionic redox upon (dis)charging. Containing the scale‐dependent features, the interpretable ML model based on a gradient‐boosting machine predicts each formation energy well. With data‐driven comprehension, honeycomb‐ and turtle‐type superstructures (TS) have been suggested depending on the thermodynamic (un)favorable pathways during desodiation from a local structural perspective, and the dangling O2– in the TS is a critical origin leading to the formation of O2 molecules trapped in the bulk. [ABSTRACT FROM AUTHOR]

In this research, the adsorption performance of individual atoms on the surface of monolayer graphene surface was systematically investigated using machine learning methods to accelerate density functional theory. The adsorption behaviors of over thirty different atoms on the graphene surface were computationally analyzed. The adsorption energy and distance were extracted as the research targets, and the basic information of atoms (such as atomic radius, ionic radius, etc.) were used as the feature values to establish the dataset. Through feature engineering selection, the corresponding input feature values for the input-output relationship were determined. By comparing different models on the dataset using five-fold cross-validation, the mathematical model that best fits the dataset was identified. The optimal model was further fine-tuned by adjusting of the best mathematical ML model. Subsequently, we verified the accuracy of the established machine learning model. Finally, the precision of the machine learning model forecasts was verified by the method of comparing and contrasting machine learning results with density functional theory. The results suggest that elements such as Zr, Ti, Sc, and Si possess some potential in controlling the interfacial reaction of graphene/aluminum composites. By using machine learning to accelerate first-principles calculations, we have further expanded our choice of research methods and accelerated the pace of studying element–graphene interactions. [ABSTRACT FROM AUTHOR]

Indium (In) is a critical element for electronics and catalysis industries and a volatile metal during planet accretion. Indium isotopes can be used to study cosmochemical and geochemical processes, but no equilibrium indium isotope fractionation factor is available, which restricts our knowledge of indium enrichment and incorporation during geological processes. Here, we investigate the reduced partition function ratios (103 lnβ) of 115In/113In in indium-bearing minerals using first-principles calculations. The results show that 103 lnβ decreases in the following sequence of dzhalindite > laforetite > roquesite > cadmoindite > Ag-Sn-In-doped sphalerite ≈ Cu-In-doped sphalerite ≈ Cu-Sn-In-doped sphalerite > yixunite > indite > damiaoite > native indium. We found that chemical composition may affect indium isotope fractionation factor in indium-doped sphalerite with Zn/In from 4 to 80 and indium alloys by changing the length of indium bonds. Furthermore, the chemical composition is not only related to the bond length and coordination number (CN) of the target element but also to the electronegativity of other doped elements, which can influence equilibrium indium isotope fractionation. The variation in 103 lnβ of indium-doped sphalerites and independent minerals predicts measurable isotopic differences between indium-bearing minerals. The equilibrium indium isotope fractionation factors calculated in this study provide important guides for the potential applications of indium isotopes in geological processes. [ABSTRACT FROM AUTHOR]

Multi-component high-entropy carbides (HECs) have garnered extensive attention owing to their excellent serviceability in harsh environments characterized by ultra-high temperatures and high pressures. However, the microstructure, electronic structure, and chemical bonding of materials are significantly influenced by high pressure. This study investigates the effects of high-pressure conditions on the stability and properties of (TiZrHfVNb)C₅ phases using the first-principles calculation. According to the judgment analysis in thermodynamics, mechanics, and kinetics, HECs can form a single solid-solution phase which is stable in 0–100 GPa. When pressure is applied, HECs undergo more significant property changes. With increasing pressure, there are some increases in lattice distortion, elastic modulus, mechanical anisotropy, sound velocity, and Debye temperature of (TiZrHfVNb)C₅ ceramic. It is worth noting that hardness has a perverse behavior at high pressures, and the hardness decreases with increasing pressure. At 40–50 GPa, HECs also experience a brittle–ductile transition. A shift in HECs' electronic structure under pressure is what essentially causes the changes in brittle–ductile transition and hardness. This work provides instructive insights for predicting and designing high-performance high-entropy carbide ceramics tailored for extreme environmental conditions. [ABSTRACT FROM AUTHOR]

xTiB2/Al-9Si composites were fabricated in this study using the mixed salt reaction method. With increasing TiB2 particle content, the size of the primary α-Al grains decreased correspondingly. The best refinement of the primary α-Al grains was achieved with the addition of 4 wt.% TiB2 particles, which resulted in the highest yield and tensile strength (172.3 and 255.3 MPa, respectively) and an elongation of 1.6%. In order to explore the TiB2( 1 ¯ 100 )/α-Al( 1 ¯ 1 ¯ 1 ) interfacial structure and to understand the potential of the heterogeneous nucleation of α-Al grains on TiB2 particles, the ideal work of adhesion (Wad), electronic structure and bonding properties of the TiB2( 1 ¯ 100 )/α-Al( 1 ¯ 1 ¯ 1 ) interface were investigated utilizing density functional theory-based first-principles calculations. The calculation results demonstrated that the stacking model with a B-terminated interface had a relaxed interfacial distance of 2.093 Å, the work of adhesion of 1.24 J/m2 and the interfacial energy of 0.09 J/m2, thereby revealing the stability of this model. The calculated electron bonding indicated that strong and stable Al-B covalent bonds were generated at the interface, revealing the ability of α-Al grains to heterogeneously nucleate on TiB2 grains and the positive contribution of TiB2 particles to the grain refinement and strengthening mechanism of the Al-Si alloys. This study provides references for the in-depth study of ceramic particle-reinforced aluminum matrix composites. [ABSTRACT FROM AUTHOR]

Hydrogen storage is a crucial step in commercializing hydrogen‐based energy production. Solid‐state hydrogen storage has gained much attention from researchers and needs extensive research. In the present study, we investigate the structural, mechanical, and optoelectronic properties of lithium‐based LiAH3 (A=Mn, Fe, Co) metal hydrides to elucidate their potential for solid‐state hydrogen storage. First, we evaluate the structure stability of LiAH3 hydrides using formation enthalpies calculations. Then, the mechanical stability is determined by elastic stiffness constants, which reveal that LiAH3 hydrides are stable mechanically as they meet the Born stability requirements. Electronic band structure calculations manifest that all LiAH3 hydrides possess a metallic character. Several optical properties have been discussed in detail. The gravimetric hydrogen storage capacities of LiMnH3, LiFeH3 and LiCoH3 hydrides are 4.65, 4.60 and 4.39 wt%, respectively, achieving the target of US‐DOE for rechargeable equipment. Additionally, we have determined the volumetric hydrogen storage capacities (Cv) for all LiAH3 hydrides. It is worth mentioning that the highest Cv values have been obtained to be 180.80, 188.18 and 177.25gH2l−1 for LiMnH3, LiFeH3 and LiCoH3 hydrides, respectively, which have achieved the US‐DOE target set for 2025. Our investigation predicts the applicability of lithium‐based hydrides as promising solid‐state hydrogen storage materials. [ABSTRACT FROM AUTHOR]

Recent studies have revealed the potential of 2D moiré superlattices as a condensed matter quantum simulator. The realization of different lattice model Hamiltonians in moiré superlattices has become the focus of researches. Here, it shows that, compared to bilayer moiré superlattices where there is only one interface, the interference between moiré patterns at different interfaces in 2D multilayer structures allows the physical realization of more complicated lattice models. The concept is demonstrated by trilayer moiré superlattices (TMSLs) of MoS2, where it finds that isolated flat moiré bands appear near the valence band edge, and they can be described by the honeycomb lattice ionic Hubbard model. More importantly, the hopping strength, the on‐site Coulomb repulsion, and the staggered potential in the TMSLs are highly tunable through the control of the twist angle, the dielectric environment, and the perpendicular electric field. It is possible to achieve various transitions between distinct quantum phases in the TMSLs, spanning from weak to strong correlation regimes. Therefore, the proposed TMSLs can serve as a good platform to study the strong correlation physics in the honeycomb lattice ionic Hubbard model. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials have emerged as highly promising photocatalysts for solar-driven water splitting. They have garnered significant interest owing to their large specific surface areas and short carrier migration distances. Our study focused on the theoretical prediction of promising photocatalysts for solar-driven water splitting in XAu 4 Y (X, Y= Se, Te) monolayers and their corresponding heterostructures using first-principles calculations. XAu 4 Y are semiconductors with indirect bandgaps of 1.27–1.54 eV. Owing to their appropriate band edges, SeAu 4 Se and SeAu 4 Te were found to be suitable for solar-driven water splitting. Importantly, SeAu 4 Te achieved a Janus-induced internal electric field of 0.80 V/Å, which favored the separation of photogenerated carriers, thus improving the photocatalytic efficiency. Further, SeAu 4 Se/TeAu 4 Te and SeAu 4 Se/TeAu 4 Se heterostructures were predicted to be high-performance Z(S)-scheme photocatalysts for hydrogen evolution with strong redox abilities, efficient separation of photogenerated carriers, and enhanced light absorptions. Our findings may provide valuable insights for realizing high-performance photocatalysts for water splitting. [Display omitted] • SeAu 4 Se and SeAu 4 Te are promising solar-driven photocatalysts for water splitting. • Janus SeAu 4 Te achieve a built-in electric field to restrain electron-hole recombination. • SeAu 4 Se/TeAu 4 Te, SeAu 4 Se/TeAu 4 Se, and TeAu 4 Te/SeAu 4 Te are staggered band alignments. • SeAu 4 Se/TeAu 4 Te and SeAu 4 Se/TeAu 4 Se are efficient Z(S)-scheme charge transport mechanisms. [ABSTRACT FROM AUTHOR]