The adsorptive denitrification performance of MIL-101(Cr)-0.5 toward pyridine,aniline or quinoline in simulated fuels with basic nitrogen content of 1732μg/g was evaluated separately.Furthermore,the effects of adsorp...The adsorptive denitrification performance of MIL-101(Cr)-0.5 toward pyridine,aniline or quinoline in simulated fuels with basic nitrogen content of 1732μg/g was evaluated separately.Furthermore,the effects of adsorption temperature,adsorption time and adsorbent dosage on their adsorptive denitrification performance were systematically investigated.The experimental results demonstrated that under a fixed adsorbent dosage of 0.05 g and a simulated fuel volume of 10 mL,the optimal removal efficiency for aniline was achieved at 30℃ within 30 min,whereas higher temperatures and longer times(40℃and 40 min)were required for effective removal of pyridine and quinoline.Density Functional Theory(DFT)calculations were conducted via Materials Studio(MS)software to study the adsorptive denitrification mechanism of MIL-101(Cr)toward these three basic nitrogen-containing compounds.The simulation calculation results revealed that the interaction between pyridine and MIL-101(Cr)primarily involved coordination adsorption.In contrast,the interaction between aniline or quinoline and MIL-101(Cr)proceeded mainly through coordination,with additional contributions fromπ-complexation and hydrogen bonding.The overall adsorption strength order is pyridine>aniline>quinoline.During the adsorption process,pyridine and quinoline transfer electrons to the MIL-101(Cr)surface through the H→C→N→Cr^(3+)pathway,while aniline transfers electrons to the MIL-101(Cr)surface through various pathways,including N→Cr^(3+),N→C→Cr^(3+)and N→H→O.Furthermore,adsorption kinetics studies indicated that the adsorption processes for all three basic nitrogen-containing compounds followed the quasi second order kinetic models.The experimental results on the effect of benzene on the adsorptive denitrification performance of MIL-101(Cr)-0.5 demonstrated that benzene exerted a more significant impact on the adsorption of aniline and quinoline.Finally,the adsorbent was regenerated using ethanol washing.It was found that MIL-101(Cr)-0.5 retained stable denitrification performance after two regeneration cycles.展开更多
The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor ...The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.展开更多
The hydrogen evolution reaction(HER) is a key process in electrocatalytic water splitting for hydrogen production,yet it is often limited by sluggish H^(*)-OH adsorption and H*binding kinetics.We obtained Rumodified N...The hydrogen evolution reaction(HER) is a key process in electrocatalytic water splitting for hydrogen production,yet it is often limited by sluggish H^(*)-OH adsorption and H*binding kinetics.We obtained Rumodified Ni O nanoparticles(Ru-Ni O/NF) with enhanced HER properties by substituting ruthenium(Ru)for Ni atoms in the Ni O(200) crystalline facets on nickel foam by a one-step electrodeposition technique.This novel catalyst exhibits a significantly reduced H^(*)-OH adsorption energy and improved kinetics,with an overpotential of only 60 mV at 10 mA/cm^(2) and a Tafel slope of 26.19 mV/dec.The Ru-Ni O/NF maintains its activity for over 115 h,outperforming NiO/NF by reducing the overpotential by 177 mV.DFT calculations confirm that the addition of Ru to NiO enhances the HER kinetics by modifying the electronic structure,optimizing the surface chemistry,stabilizing the intermediates,lowering the energy barriers,and facilitating efficient charge transfer through a robust three-dimensional structure,resulting in a change in the rate-limiting step and a significant reduction in the Gibbs free energy.This study presents a highly efficient HER catalyst and offers insights into designing advanced NiO-based electrocatalysts by reducing reaction energy barriers.展开更多
Charge-transfer complexes(CTCs)have emerged as promising n-type organic thermoelectric(TE)materials due to their inherent high electrical conductivity and tunable transport polarities.In this study,we performed a comp...Charge-transfer complexes(CTCs)have emerged as promising n-type organic thermoelectric(TE)materials due to their inherent high electrical conductivity and tunable transport polarities.In this study,we performed a comprehensive first-principles investigation on the TE properties of nine CTCs comprised of 2,7-dialkyl[1]benzothieno[3,2-b][1]benzothiophenes(CnBTBT,n=4,8,12)as donors and fluorinated derivatives of tetracyanoquinodimethane(F_(m)TCNQ,m=0,2,4)as acceptors,aiming to identify high-performance n-type organic TE materials and elucidate the underlying structure-property relationships.Our calculation results,based on the Boltzmann transport equation and deformation potential theory,reveal that the length of the alkyl side chains and the number of fluorine substitutions significantly impact their electronic structures and TE properties.Notably,the CnBTBT-F_(m)TCNQ CTCs with shorter alkyl chains and more fluorine substitution demonstrate superior n-type characteristics,particularly C4BTBT-F4TCNQ,which achieves an excellent power factor of 671µW cm^(-1) K^(-2) at an optimal charge carrier concentration.Our findings not only clarify the critical role of molecular engineering in CTC-based TE materials but also provide valuable guidance for developing high-efficiency organic TE materials with versatile practical applications.展开更多
Oxygen evolution reaction(OER)is widely recognized as a bottleneck of water electrolysis.To determine the underlying reaction mechanisms,particularly the relative contribution of the adsorbate evolution mechanism(AEM)...Oxygen evolution reaction(OER)is widely recognized as a bottleneck of water electrolysis.To determine the underlying reaction mechanisms,particularly the relative contribution of the adsorbate evolution mechanism(AEM)and lattice-oxygen participation mechanism(LOM),we conduct a comprehensive investigation combining Density Functional Theory(DFT)calculations and experimental validation.Our theoretical analysis of doped RuO_(2)catalysts reveals that heteroatom doping(Ni,Cu,and Zn)induces significant local charge transfer,leading to the increased charge state of Ru and the downshifted d-band center.This,in turn,enables the mechanism switching from the conventional AEM to the more efficient LOM,and finally improves OER activity.We also establish a simple yet powerful descriptor,Ne of Ru(representing charge density of Ru sites),which enables accurate prediction of both catalytic activity and stability.Guided by these theoretical predictions,we successfully synthesize a Ni-doped RuO_(2)catalyst,which exhibits excellent OER activity and stability in acidic media,achieving an overpotential of just 156 mV and maintaining stability for 4000 h at 10 mA cm^(−2),significantly surpassing the performance of the commercial RuO_(2).These findings not only provide fundamental insights into the mechanism-switching behavior in OER catalysis but also offer a practical strategy for designing high-performance,stable electrocatalysts for acidic water electrolysis.展开更多
Owing to their intricate molecular frameworks and copious chiral centers,the structural identification and configurational assignment of natural products are challenging tasks.Comprehensive spectral data analysis is c...Owing to their intricate molecular frameworks and copious chiral centers,the structural identification and configurational assignment of natural products are challenging tasks.Comprehensive spectral data analysis is crucial for the confirmation of absolute configurations.Ignoring critical parameters will lead to false structure,which may confuse the total synthesis and drug development.Herein,the configurations of seven heterogeneous Pallavicinia diterpenoids(PDs) isolated from Pallavicinia liverworts are revised using a combination of single-crystal X-ray diffraction and electronic circular dichroism(ECD) calculations.Meanwhile,identification of five unprecedented PD heterodimers PD-dimers A-E(18-22) along with eleven previously undescribed PDs(5-9,13-17,23) obtained by the reinvestigation of the Chinese liverwort Pallavicinia subciliata have resulted in corrections and support the revised conclusions.展开更多
Two-dimensional(2D)multilayer kagome materials hold significant research value for regulating kagome-related physical properties and exploring quantum effects.However,their development is hindered by the scarcity of a...Two-dimensional(2D)multilayer kagome materials hold significant research value for regulating kagome-related physical properties and exploring quantum effects.However,their development is hindered by the scarcity of available material systems,making the identification of novel 2D multilayer kagome candidates particularly important.In this work,three types of 2D materials with trilayer kagome lattices,namely Sc_(6)S_(5)X_(6)(X=Cl,Br,I),are predicted based on first-principles calculations.These 2D materials feature two kagome lattices composed of Sc atoms and one kagome lattice composed of S atoms.Stability analysis indicates that these materials can exist as free-standing 2D materials.Electronic structure calculations reveal that Sc_(6)S_(5)X_(6)are narrow-bandgap semiconductors(0.76–0.95 e V),with their band structures exhibiting flat bands contributed by Sc-based kagome lattices and Dirac band gaps resulting from symmetry breaking.The sulfur-based kagome lattice in the central layer contributes an independent flat band below the Fermi level.Additionally,Sc_(6)S_(5)X_(6)exhibit high carrier mobility,with hole and electron mobilities reaching up to 10^(3)cm^(2)·V^(-1)·s^(-1),indicating potential applications in low-dimensional electronic devices.This work provides an excellent example for the development of novel multilayer 2D kagome materials.展开更多
Superconductivity in two-dimensional(2D)materials has attracted considerable attention due to their unique physical properties and potential for high-temperature operation.Boron-based 2D compounds are particularly pro...Superconductivity in two-dimensional(2D)materials has attracted considerable attention due to their unique physical properties and potential for high-temperature operation.Boron-based 2D compounds are particularly promising,thanks to their structural flexibility and the emergence of strong electron-phonon coupling(EPC)associated with light elements.While most previous studies have focused on stabilizing boron sheets through metal incorporation,we propose an alternative approach based on multicenter bonding enabled by group-IV non-metallic elements(Si,Ge,Sn).The resulting XB_(2)(X=Si,Ge,Sn)monolayers,which adopt a MgB_(2)-like monolayer configuration,are stabilized by a seven-center two-electron(7c-2e)bonding network between the X atoms and the boron honeycomb lattice.This bonding lowers the energy of the B-p_(z)orbitals and enhances lattice stability.The superconducting transition temperature(T_(c))increases significantly with the atomic number of X—from 4.7 K in SiB_(2)to 13.3 K in GeB_(2)and 24.9 K in SnB_(2)—driven by an increased carrier density near the Fermi level(E_(F))and softening of the high-frequency E_(2)phonon mode.Furthermore,we design a SnB_4 monolayer,in which a Sn layer is sandwiched between the two boron layers.This structure enriches in-plane phonon modes and strengthens EPC,yielding a T_(c)of 38 K,close to the McMillan limit.These findings highlight the critical role of multicenter bonding and targeted phonon engineering in enabling high-T_(c)2D boron-based superconductors.展开更多
The development of high-performance solid electrolytes is pivotal for advancing solid-state battery technologies.In this work,we design an oxysulfide-based solid electrolyte Na MgPO_(3)S by combining bond valence theo...The development of high-performance solid electrolytes is pivotal for advancing solid-state battery technologies.In this work,we design an oxysulfide-based solid electrolyte Na MgPO_(3)S by combining bond valence theory and density functional theory calculations.The material features a wide band gap of 4.0 eV and a considerable reduced Na^(+)migration barrier of 0.44 eV,a 1.26-eV decrease compared to pristine Na MgPO_(4)(~1.70 eV).Ab initio molecular dynamics simulations further reveal significantly enhanced ionic conductivity in the oxysulfide-based system compared to the pristine oxide structure.In addition,the calculated decomposition energy indicates that the modified material exhibits good moisture stability.Our findings suggest that sulfur-doping strategy can simultaneously achieve improved ionic conductivity and high moisture stability in oxide solid electrolytes,which could pave the way for designing high-performance solid electrolytes.展开更多
Interfacial superconductivity(IS)has been a topic of intense interest in condensed matter physics,due to its unique properties and exotic photoelectrical performance.However,there are few reports about IS systems cons...Interfacial superconductivity(IS)has been a topic of intense interest in condensed matter physics,due to its unique properties and exotic photoelectrical performance.However,there are few reports about IS systems consisting of two insulators.Here,motivated by the emergence of an insulator-metal transition in type-Ⅲ heterostructures and the superconductivity in some“special”two-dimensional(2D)semiconductors via electron doping,we predict that the 2D heterostructure SnSe_(2)/PtTe_(2) is a model system for realizing IS by using firstprinciples calculations.Our results show that due to slight but crucial interlayer charge transfer,SnSe_(2)/PtTe_(2) turns to be a type-Ⅲ heterostructure with metallic properties and shows a superconducting transition with the critical temperature(T_(c))of 3.73 K.Similar to the enhanced electron–phonon coupling(EPC)in the electrondoped SnSe_(2) monolayer,the IS in the SnSe_(2)/PtTe_(2) heterostructure mainly originates from the metallized SnSe_(2) layer.Furthermore,we find that its superconductivity is sensitive to tensile lattice strain,forming a domeshaped superconducting phase diagram.Remarkably,at 7%biaxial tensile strain,the superconducting T_(c) can increase more than twofold(8.80 K),resulting from softened acoustic phonons at the𝑀point and enhanced EPC strength.Our study provides a concrete example for realizing IS in type-Ⅲ heterostructures,which waits for future experimental verification.展开更多
Strong long-wavelength laser pulses enable direct manipulation of atomic lattices for engineering novel quantum states in complex materials.Nonlinear coupling between two infrared-active phonon modes(TO_(1) and TO_(2)...Strong long-wavelength laser pulses enable direct manipulation of atomic lattices for engineering novel quantum states in complex materials.Nonlinear coupling between two infrared-active phonon modes(TO_(1) and TO_(2)),induced by intense terahertz light fields,significantly enhances the amplitude of the TO_(1) mode and facilitates ultrafast control of transient structural distortions.This light-induced distortion reduces the lattice thermal conductivity from 8.1 W·m^(-1)·K^(-1)to 3.0 W·m^(-1)·K^(-1).The reduction originates from the nonlinear coupling,which enhances anharmonic interactions in the lattice potential energy and substantially shortens the phonon lifetime(τ).This work demonstrates a strategy applicable to other perovskite materials and provides a framework for investigating light-induced electrical,optical,and thermodynamic phase transitions.展开更多
Underwater gas-liquid two-phase propulsion technology is an emerging propulsion method that offers high efficiency and unrestricted navigation speed.The integration of this technology into water ramjet engines can sig...Underwater gas-liquid two-phase propulsion technology is an emerging propulsion method that offers high efficiency and unrestricted navigation speed.The integration of this technology into water ramjet engines can significantly enhance propulsion efficiency and holds substantial potential for broad applications.However,forming a gas-liquid two-phase flow within the nozzle requires introducing a large amount of rammed seawater.At this time,there is a complex phase transition problem of combustion products in the combustion chamber,which makes the thermodynamic calculation for gas-liquid two-phase water ramjet engines particularly challenging.This paper proposes a thermodynamic calculation method for gas-liquid two-phase water ramjet engines,based on the energy equation for gas-liquid two-phase flow and traditional thermodynamic principles,enabling thermodynamic calculations under conditions of ultra-high water-fuel ratios.Additionally,ground ignition tests of the gas-liquid two-phase engine were conducted,yielding critical engine test parameters.The results demonstrate that the gas-liquid two-phase water ramjet engine achieves a high specific impulse,with a theoretical maximum specific impulse of up to 7000(N s)/kg.The multiphase flow effects significantly impact engine performance,with specific impulse losses reaching up to 25.86%.The error between the thrust and specific impulse in the ground test and the theoretical values is within 10%,validating the proposed thermodynamic calculation method as a reliable reference for further research on gas-liquid two-phase water ramjet engines.展开更多
The electric double layer(EDL)at the electrochemical interface is crucial for ion transport,charge transfer,and surface reactions in aqueous rechargeable zinc batteries(ARZBs).However,Zn anodes routinely encounter per...The electric double layer(EDL)at the electrochemical interface is crucial for ion transport,charge transfer,and surface reactions in aqueous rechargeable zinc batteries(ARZBs).However,Zn anodes routinely encounter persistent dendrite growth and parasitic reactions,driven by the inhomogeneous charge distribution and water-dominated environment within the EDL.Compounding this,classical EDL theory,rooted in meanfield approximations,further fails to resolve molecular-scale interfacial dynamics under battery-operating conditions,limiting mechanistic insights.Herein,we established a multiscale theoretical calculation framework from single molecular characteristics to interfacial ion distribution,revealing the EDL’s structure and interactions between different ions and molecules,which helps us understand the parasitic processes in depth.Simulations demonstrate that water dipole and sulfate ion adsorption at the inner Helmholtz plane drives severe hydrogen evolution and by-product formation.Guided by these insights,we engineered a“water-poor and anion-expelled”EDL using 4,1’,6’-trichlorogalactosucrose(TGS)as an electrolyte additive.As a result,Zn||Zn symmetric cells with TGS exhibited stable cycling for over 4700 h under a current density of 1 mA cm^(−2),while NaV_(3)O_(8)·1.5H_(2)O-based full cells kept 90.4%of the initial specific capacity after 800 cycles at 5 A g^(−1).This work highlights the power of multiscale theoretical frameworks to unravel EDL complexities and guide high-performance ARZB design through integrated theory-experiment approaches.展开更多
Low-density superalloys often exhibit low yield strength in the intermediate temperature range(300−650℃).To enhance yield performance in this range,the CALPHAD method was used to design a new Co-based superalloy.The ...Low-density superalloys often exhibit low yield strength in the intermediate temperature range(300−650℃).To enhance yield performance in this range,the CALPHAD method was used to design a new Co-based superalloy.The Co−30Ni−10Al−3V−6Ti−2Ta alloy,designed based onγʹphase dissolution temperature and phase fraction,was synthesized via arc melting and heat treatment.Phase transition temperatures,microstructure evolution,and hightemperature mechanical properties were characterized by differential scanning calorimetry,scanning electron microscopy,dual-beam TEM,and compression tests.Results show that the alloy has low density(8.15 g/cm^(3))and highγʹdissolution temperature(1234℃),along with unique yield strength retention from room temperature to 650℃.The yield strength anomaly(YSA)is attributed to high stacking fault energy and activation of the Kear−Wilsdorf locking mechanism,contributing to superior high-temperature stability of the alloy.The yield strength of this alloy outperforms other lowdensity Co-based superalloys in the temperature range of 23−650℃.展开更多
Moirésuperlattices hosting flat bands and correlated states have become a central focus in condensed matter research.Using first-principles calculations,we investigate three-dimensional flat bands in alternating ...Moirésuperlattices hosting flat bands and correlated states have become a central focus in condensed matter research.Using first-principles calculations,we investigate three-dimensional flat bands in alternating twisted NbSe_(2)moirébulk structures,which exhibit stronger interlayer interactions than twisted bilayer configurations.Our results show that moirébulks undergo spontaneous large-scale structural relaxation,leading to the formation of remarkably flat energy bands at twist angles≤7.31°.The k_(z)-dependent dispersion of these flat bands across different moirébulks highlights their intrinsic three-dimensional character.Moreover,the presence of out-of-plane mirror symmetry in these moirébulk structures indicates potential interlayer triplet superconducting pairing mechanisms,distinct from those in twisted bilayer systems.This work opens new avenues for exploring three-dimensional flat bands in other moirébulk systems.展开更多
The excessive use of pesticides has exacerbated environmental pollution due to herbicide residues,while their persistent toxicity poses serious challenges to global ecological security.A magnetically recyclable CoFe_(...The excessive use of pesticides has exacerbated environmental pollution due to herbicide residues,while their persistent toxicity poses serious challenges to global ecological security.A magnetically recyclable CoFe_(2)O_(4)/BiOBr S-scheme heterojunctions was prepared by microwave-assisted co-precipitation method for photocatalytic degradation of Diuron(DUR) in water.The formation of S-scheme heterojunction enhances electron transfer and charge separation,which was demonstrated by free radical trapping,electrochemical experiments,and DFT calculations.The magnetic CoFe_(2)O_(4)/BiOBr catalysts can achieve 99.9 %removal of diuron in 50 min under visible light irradiation.Furthermore,the system maintains stable performance across a broad p H range(3-9),enabling adaptation to diverse water environments,effective elimination of multiple pollutants,and strong resistance to ionic interference.Using magnetic recovery,CoFe_(2)O_(4)/BiOBr exhibits a high removal rate of 99 % and a markedly low ion leaching rate(<20 μg/L) after six cycles photocatalytic process,confirming its excellent stability and durability.According to HPLCQTOF-MS and DFT calculation,the main ways of DUR degradation include dechlorinated hydroxylation,dealkylation and hydroxylation of aromatic ring and side chain.Toxicity analysis showed that the toxicity of the intermediates generated during degradation was generally lower than that of DUR.The magnetic CoFe_(2)O_(4)/BiOBr S-scheme heterojunction developed in this study exhibits excellent photocatalytic performance,high applicability,good stability,and durability,providing an effective magnetic for the removal of refractory pollutants.展开更多
Abiotic oxygen formation predates photosynthesis,sustaining early chemical evolution,yet its elementary mechanisms remain contested.Here,we show the production pathways for molecular oxygen from doubly ionized carbon ...Abiotic oxygen formation predates photosynthesis,sustaining early chemical evolution,yet its elementary mechanisms remain contested.Here,we show the production pathways for molecular oxygen from doubly ionized carbon dioxide upon electron-impact.Through fragment ions and electron coincidence momentum imaging,we unambiguously determine the ionization mechanism by measuring the projectile energy loss in association with the C^(+) +O_(2)^(+) channel.Further potential energy and trajectory calculations enable us to elucidate the dynamical details of this fragmentation process,in which a bond rearrangement pathway is found to proceed via the structural deformation to a triangular intermediate.Moreover,we demonstrate a further roaming pathway for the formation of O_(2)^(+) from CO_(2)^(+) 2,in which a frustrated C-O bond cleavage leaves the O atom without sufficient energy to escape.The O atom then wanders around varied configuration spaces of the flat potential energy regions and forms a C-O-O_(2)^(+) intermediate prior to the final products C^(+) +O_(2)^(+).Considering the large quantities of free electrons in interstellar space,the processes revealed here are expected to be significant and should be incorporated into atmospheric evolution models.展开更多
The interfacial properties of Schottky contacts crucially affect the performance of power devices. While a few studies have explored the impact of fluorine on Schottky contacts, a comprehensive theoretical explanation...The interfacial properties of Schottky contacts crucially affect the performance of power devices. While a few studies have explored the impact of fluorine on Schottky contacts, a comprehensive theoretical explanation supported by experimental evidence remains lacking. This work investigates the effects of fluorine incorporation and electrothermal annealing(ETA) on the current transport process at Ni/β-Ga_(2)O_(3) Schottky contacts. X-ray photoelectron spectroscopy and first-principles calculations confirm the presence of fluorine substitutions for oxygen and oxygen vacancies and their lowering effect on the Schottky barrier heights. Additionally, accurate electrothermal hybrid TCAD simulations validates the extremely short-duration high temperatures(683 K) induced by ETA, which facilitates lattice rearrangement and reduces interface trap states. The interface trap states are quantitatively resolved through frequency-dependent conductance technique, showing the trap density(DT)reduction from(0.88-2.48) × 10^(11) cm^(-2)·eV^(-1) to(0.46-2.09) × 10^(11) cm^(-2)·eV^(-1). This investigation offers critical insights into the β-Ga_(2)O_(3) contacts with the collaborative treatment and solids the promotion of high-performance β-Ga_(2)O_(3) power devices.展开更多
We report a theoretical investigation into superconductivity within the MAXH_(6) quaternary hydride system using first-principles calculations,where M and A denote alkali and alkaline earth elements,respectively,and X...We report a theoretical investigation into superconductivity within the MAXH_(6) quaternary hydride system using first-principles calculations,where M and A denote alkali and alkaline earth elements,respectively,and X represents transition metal elements.Systematic analysis of electronic band structures,phonon dispersions,and electron-phonon coupling reveals that substitution of MA binary metal combinations and X metal atoms can create favorable conditions for superconductivity.Mapping of superconducting critical temperatures,combined with dynamical stability analysis through phonon calculations,identifies ten superconducting candidates at ambient pressure.Among these,LiNaAgH_(6) exhibits nearly-free-electron behavior reminiscent of monovalent electron superconductors.It demonstrates exceptional superconducting properties with electron–phonon coupling λ=2.707,which yields a superconducting transition temperature T_(c) of 206.4 K using the Allen–Dynes formula.Its structural analogs MgNaPdH_(6),LiMgPdH_(6),LiMgAgH_(6),LiMgAuH_(6) all exhibit superconducting transition temperatures above 110 K.These findings advance our fundamental understanding of superconductivity in quaternary hydrides and provide guidance for rational design of new high-temperature superconducting materials.展开更多
基金Supported by Basic Scientific Research Project of the Liaoning Provincial Department of Education Has Been Unveiled to Facilitate Local Project Funding (JYTMS20230835)Enhanced Scientific Research Project Funded by the Departmentof Higher Education in Liaoning Province (General program)(JYTMS20230852)。
文摘The adsorptive denitrification performance of MIL-101(Cr)-0.5 toward pyridine,aniline or quinoline in simulated fuels with basic nitrogen content of 1732μg/g was evaluated separately.Furthermore,the effects of adsorption temperature,adsorption time and adsorbent dosage on their adsorptive denitrification performance were systematically investigated.The experimental results demonstrated that under a fixed adsorbent dosage of 0.05 g and a simulated fuel volume of 10 mL,the optimal removal efficiency for aniline was achieved at 30℃ within 30 min,whereas higher temperatures and longer times(40℃and 40 min)were required for effective removal of pyridine and quinoline.Density Functional Theory(DFT)calculations were conducted via Materials Studio(MS)software to study the adsorptive denitrification mechanism of MIL-101(Cr)toward these three basic nitrogen-containing compounds.The simulation calculation results revealed that the interaction between pyridine and MIL-101(Cr)primarily involved coordination adsorption.In contrast,the interaction between aniline or quinoline and MIL-101(Cr)proceeded mainly through coordination,with additional contributions fromπ-complexation and hydrogen bonding.The overall adsorption strength order is pyridine>aniline>quinoline.During the adsorption process,pyridine and quinoline transfer electrons to the MIL-101(Cr)surface through the H→C→N→Cr^(3+)pathway,while aniline transfers electrons to the MIL-101(Cr)surface through various pathways,including N→Cr^(3+),N→C→Cr^(3+)and N→H→O.Furthermore,adsorption kinetics studies indicated that the adsorption processes for all three basic nitrogen-containing compounds followed the quasi second order kinetic models.The experimental results on the effect of benzene on the adsorptive denitrification performance of MIL-101(Cr)-0.5 demonstrated that benzene exerted a more significant impact on the adsorption of aniline and quinoline.Finally,the adsorbent was regenerated using ethanol washing.It was found that MIL-101(Cr)-0.5 retained stable denitrification performance after two regeneration cycles.
文摘The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.
基金supported by the National Natural Science Foundation of China (No.22275052)Department of Science and Technology of Hubei Province (Nos.2025AFA111 and 2024CSA076)。
文摘The hydrogen evolution reaction(HER) is a key process in electrocatalytic water splitting for hydrogen production,yet it is often limited by sluggish H^(*)-OH adsorption and H*binding kinetics.We obtained Rumodified Ni O nanoparticles(Ru-Ni O/NF) with enhanced HER properties by substituting ruthenium(Ru)for Ni atoms in the Ni O(200) crystalline facets on nickel foam by a one-step electrodeposition technique.This novel catalyst exhibits a significantly reduced H^(*)-OH adsorption energy and improved kinetics,with an overpotential of only 60 mV at 10 mA/cm^(2) and a Tafel slope of 26.19 mV/dec.The Ru-Ni O/NF maintains its activity for over 115 h,outperforming NiO/NF by reducing the overpotential by 177 mV.DFT calculations confirm that the addition of Ru to NiO enhances the HER kinetics by modifying the electronic structure,optimizing the surface chemistry,stabilizing the intermediates,lowering the energy barriers,and facilitating efficient charge transfer through a robust three-dimensional structure,resulting in a change in the rate-limiting step and a significant reduction in the Gibbs free energy.This study presents a highly efficient HER catalyst and offers insights into designing advanced NiO-based electrocatalysts by reducing reaction energy barriers.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Science(No.XDB0520000)the National Natural Science Foundation of China(Nos.52273170 and 52394271)the National Key R&D Program of China(No.2022YFA1203200).
文摘Charge-transfer complexes(CTCs)have emerged as promising n-type organic thermoelectric(TE)materials due to their inherent high electrical conductivity and tunable transport polarities.In this study,we performed a comprehensive first-principles investigation on the TE properties of nine CTCs comprised of 2,7-dialkyl[1]benzothieno[3,2-b][1]benzothiophenes(CnBTBT,n=4,8,12)as donors and fluorinated derivatives of tetracyanoquinodimethane(F_(m)TCNQ,m=0,2,4)as acceptors,aiming to identify high-performance n-type organic TE materials and elucidate the underlying structure-property relationships.Our calculation results,based on the Boltzmann transport equation and deformation potential theory,reveal that the length of the alkyl side chains and the number of fluorine substitutions significantly impact their electronic structures and TE properties.Notably,the CnBTBT-F_(m)TCNQ CTCs with shorter alkyl chains and more fluorine substitution demonstrate superior n-type characteristics,particularly C4BTBT-F4TCNQ,which achieves an excellent power factor of 671µW cm^(-1) K^(-2) at an optimal charge carrier concentration.Our findings not only clarify the critical role of molecular engineering in CTC-based TE materials but also provide valuable guidance for developing high-efficiency organic TE materials with versatile practical applications.
基金supported by the National Natural Science Foundation of China(22472104)Guangdong Basic and Applied Basic Research Foundation(2024A1515012075,2024A1515010028)the Postdoctoral Fellowship Program of CPS Funder(GZC20241083,2025M771117)。
文摘Oxygen evolution reaction(OER)is widely recognized as a bottleneck of water electrolysis.To determine the underlying reaction mechanisms,particularly the relative contribution of the adsorbate evolution mechanism(AEM)and lattice-oxygen participation mechanism(LOM),we conduct a comprehensive investigation combining Density Functional Theory(DFT)calculations and experimental validation.Our theoretical analysis of doped RuO_(2)catalysts reveals that heteroatom doping(Ni,Cu,and Zn)induces significant local charge transfer,leading to the increased charge state of Ru and the downshifted d-band center.This,in turn,enables the mechanism switching from the conventional AEM to the more efficient LOM,and finally improves OER activity.We also establish a simple yet powerful descriptor,Ne of Ru(representing charge density of Ru sites),which enables accurate prediction of both catalytic activity and stability.Guided by these theoretical predictions,we successfully synthesize a Ni-doped RuO_(2)catalyst,which exhibits excellent OER activity and stability in acidic media,achieving an overpotential of just 156 mV and maintaining stability for 4000 h at 10 mA cm^(−2),significantly surpassing the performance of the commercial RuO_(2).These findings not only provide fundamental insights into the mechanism-switching behavior in OER catalysis but also offer a practical strategy for designing high-performance,stable electrocatalysts for acidic water electrolysis.
基金supported by the National Natural Science Foundation of China (Nos.82293682,82293684,and 82173703)。
文摘Owing to their intricate molecular frameworks and copious chiral centers,the structural identification and configurational assignment of natural products are challenging tasks.Comprehensive spectral data analysis is crucial for the confirmation of absolute configurations.Ignoring critical parameters will lead to false structure,which may confuse the total synthesis and drug development.Herein,the configurations of seven heterogeneous Pallavicinia diterpenoids(PDs) isolated from Pallavicinia liverworts are revised using a combination of single-crystal X-ray diffraction and electronic circular dichroism(ECD) calculations.Meanwhile,identification of five unprecedented PD heterodimers PD-dimers A-E(18-22) along with eleven previously undescribed PDs(5-9,13-17,23) obtained by the reinvestigation of the Chinese liverwort Pallavicinia subciliata have resulted in corrections and support the revised conclusions.
基金supported by the Fundamental Research Funds for the Central Universities(WUT:2024IVA052 and Grant No.104972025KFYjc0089)。
文摘Two-dimensional(2D)multilayer kagome materials hold significant research value for regulating kagome-related physical properties and exploring quantum effects.However,their development is hindered by the scarcity of available material systems,making the identification of novel 2D multilayer kagome candidates particularly important.In this work,three types of 2D materials with trilayer kagome lattices,namely Sc_(6)S_(5)X_(6)(X=Cl,Br,I),are predicted based on first-principles calculations.These 2D materials feature two kagome lattices composed of Sc atoms and one kagome lattice composed of S atoms.Stability analysis indicates that these materials can exist as free-standing 2D materials.Electronic structure calculations reveal that Sc_(6)S_(5)X_(6)are narrow-bandgap semiconductors(0.76–0.95 e V),with their band structures exhibiting flat bands contributed by Sc-based kagome lattices and Dirac band gaps resulting from symmetry breaking.The sulfur-based kagome lattice in the central layer contributes an independent flat band below the Fermi level.Additionally,Sc_(6)S_(5)X_(6)exhibit high carrier mobility,with hole and electron mobilities reaching up to 10^(3)cm^(2)·V^(-1)·s^(-1),indicating potential applications in low-dimensional electronic devices.This work provides an excellent example for the development of novel multilayer 2D kagome materials.
基金supported by the National Natural Science Foundation of China(Grant Nos.22372142,12304028,12404027)the Foreign Expert Introduction Program(Grant No.G2023003004L)+6 种基金the Central Guiding Local Science and Technology Development Fund Projects(Grant No.236Z7605G)the Natural Science Foundation of Hebei Province(Grant Nos.B2024203051,A2024203023,A2024203002)the Science and Technology Project of Hebei Education Department(Grant No.JZX2023020)the Innovation Capability Improvement Project of Hebei Province(Grant No.22567605H)the Hebei Province Yan Zhao Huang Jin Tai Talent Program(Postdoctoral Platform,Grant No.B2024003003)the financial support from the Spanish Ministry of Science and Innovation(Grant No.PID2022139230NB-I00)the Department of Education,Universities and Research of the Basque Government and the University of the Basque Country(Grant No.IT1707-22)。
文摘Superconductivity in two-dimensional(2D)materials has attracted considerable attention due to their unique physical properties and potential for high-temperature operation.Boron-based 2D compounds are particularly promising,thanks to their structural flexibility and the emergence of strong electron-phonon coupling(EPC)associated with light elements.While most previous studies have focused on stabilizing boron sheets through metal incorporation,we propose an alternative approach based on multicenter bonding enabled by group-IV non-metallic elements(Si,Ge,Sn).The resulting XB_(2)(X=Si,Ge,Sn)monolayers,which adopt a MgB_(2)-like monolayer configuration,are stabilized by a seven-center two-electron(7c-2e)bonding network between the X atoms and the boron honeycomb lattice.This bonding lowers the energy of the B-p_(z)orbitals and enhances lattice stability.The superconducting transition temperature(T_(c))increases significantly with the atomic number of X—from 4.7 K in SiB_(2)to 13.3 K in GeB_(2)and 24.9 K in SnB_(2)—driven by an increased carrier density near the Fermi level(E_(F))and softening of the high-frequency E_(2)phonon mode.Furthermore,we design a SnB_4 monolayer,in which a Sn layer is sandwiched between the two boron layers.This structure enriches in-plane phonon modes and strengthens EPC,yielding a T_(c)of 38 K,close to the McMillan limit.These findings highlight the critical role of multicenter bonding and targeted phonon engineering in enabling high-T_(c)2D boron-based superconductors.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.22473010,22303114,and 12474372)the Fundamental Research Funds for the Central Universities,Jilin University,the National Key Research and Development Program of China(Grant No.SQ2023YFB2805600)+4 种基金the Natural Science Foundation of Beijing Municipality(Grant No.Z210004)the Fund from the State Key Laboratory of Information Photonics and Optical Communications(Grant No.IPOC2021ZT01)Beijing Nova Program from Beijing Municipal Science and Technology Commission(Grant No.20230484433)Beijing University of Posts and Telecommunications Excellent Ph.D.Students Foundation(Grant No.CX20241078)Beijing Natural Science Foundation(Undergraduate Program)(Grant No.QY24218)。
文摘The development of high-performance solid electrolytes is pivotal for advancing solid-state battery technologies.In this work,we design an oxysulfide-based solid electrolyte Na MgPO_(3)S by combining bond valence theory and density functional theory calculations.The material features a wide band gap of 4.0 eV and a considerable reduced Na^(+)migration barrier of 0.44 eV,a 1.26-eV decrease compared to pristine Na MgPO_(4)(~1.70 eV).Ab initio molecular dynamics simulations further reveal significantly enhanced ionic conductivity in the oxysulfide-based system compared to the pristine oxide structure.In addition,the calculated decomposition energy indicates that the modified material exhibits good moisture stability.Our findings suggest that sulfur-doping strategy can simultaneously achieve improved ionic conductivity and high moisture stability in oxide solid electrolytes,which could pave the way for designing high-performance solid electrolytes.
基金supported by the National Key R&D Program of China (Grant Nos.2022YFA1403103 and 2019YFA0308603)the National Natural Science Foundation of China (Grant No.12304167)the Shandong Provincial Natural Science Foundation of China (Grant No.ZR2023QA020)。
文摘Interfacial superconductivity(IS)has been a topic of intense interest in condensed matter physics,due to its unique properties and exotic photoelectrical performance.However,there are few reports about IS systems consisting of two insulators.Here,motivated by the emergence of an insulator-metal transition in type-Ⅲ heterostructures and the superconductivity in some“special”two-dimensional(2D)semiconductors via electron doping,we predict that the 2D heterostructure SnSe_(2)/PtTe_(2) is a model system for realizing IS by using firstprinciples calculations.Our results show that due to slight but crucial interlayer charge transfer,SnSe_(2)/PtTe_(2) turns to be a type-Ⅲ heterostructure with metallic properties and shows a superconducting transition with the critical temperature(T_(c))of 3.73 K.Similar to the enhanced electron–phonon coupling(EPC)in the electrondoped SnSe_(2) monolayer,the IS in the SnSe_(2)/PtTe_(2) heterostructure mainly originates from the metallized SnSe_(2) layer.Furthermore,we find that its superconductivity is sensitive to tensile lattice strain,forming a domeshaped superconducting phase diagram.Remarkably,at 7%biaxial tensile strain,the superconducting T_(c) can increase more than twofold(8.80 K),resulting from softened acoustic phonons at the𝑀point and enhanced EPC strength.Our study provides a concrete example for realizing IS in type-Ⅲ heterostructures,which waits for future experimental verification.
基金Project supported by the National Key Research and Development Program of China(Grant No.2024YFF0508503)。
文摘Strong long-wavelength laser pulses enable direct manipulation of atomic lattices for engineering novel quantum states in complex materials.Nonlinear coupling between two infrared-active phonon modes(TO_(1) and TO_(2)),induced by intense terahertz light fields,significantly enhances the amplitude of the TO_(1) mode and facilitates ultrafast control of transient structural distortions.This light-induced distortion reduces the lattice thermal conductivity from 8.1 W·m^(-1)·K^(-1)to 3.0 W·m^(-1)·K^(-1).The reduction originates from the nonlinear coupling,which enhances anharmonic interactions in the lattice potential energy and substantially shortens the phonon lifetime(τ).This work demonstrates a strategy applicable to other perovskite materials and provides a framework for investigating light-induced electrical,optical,and thermodynamic phase transitions.
基金supported by the Stable Support Fund forBasic Disciplines,China(No.3072024WD0201)。
文摘Underwater gas-liquid two-phase propulsion technology is an emerging propulsion method that offers high efficiency and unrestricted navigation speed.The integration of this technology into water ramjet engines can significantly enhance propulsion efficiency and holds substantial potential for broad applications.However,forming a gas-liquid two-phase flow within the nozzle requires introducing a large amount of rammed seawater.At this time,there is a complex phase transition problem of combustion products in the combustion chamber,which makes the thermodynamic calculation for gas-liquid two-phase water ramjet engines particularly challenging.This paper proposes a thermodynamic calculation method for gas-liquid two-phase water ramjet engines,based on the energy equation for gas-liquid two-phase flow and traditional thermodynamic principles,enabling thermodynamic calculations under conditions of ultra-high water-fuel ratios.Additionally,ground ignition tests of the gas-liquid two-phase engine were conducted,yielding critical engine test parameters.The results demonstrate that the gas-liquid two-phase water ramjet engine achieves a high specific impulse,with a theoretical maximum specific impulse of up to 7000(N s)/kg.The multiphase flow effects significantly impact engine performance,with specific impulse losses reaching up to 25.86%.The error between the thrust and specific impulse in the ground test and the theoretical values is within 10%,validating the proposed thermodynamic calculation method as a reliable reference for further research on gas-liquid two-phase water ramjet engines.
基金supported by the National Natural Science Foundation of China(52471240)the Natural Science Foundation of Zhejiang Province(LZ23B030003)+2 种基金the Fundamental Research Funds for the Central Universities(226-2024-00075)support from the Engineering and Physical Sciences Research Council(EPSRC,UK)RiR grant-RIR18221018-1EU COST CA23155。
文摘The electric double layer(EDL)at the electrochemical interface is crucial for ion transport,charge transfer,and surface reactions in aqueous rechargeable zinc batteries(ARZBs).However,Zn anodes routinely encounter persistent dendrite growth and parasitic reactions,driven by the inhomogeneous charge distribution and water-dominated environment within the EDL.Compounding this,classical EDL theory,rooted in meanfield approximations,further fails to resolve molecular-scale interfacial dynamics under battery-operating conditions,limiting mechanistic insights.Herein,we established a multiscale theoretical calculation framework from single molecular characteristics to interfacial ion distribution,revealing the EDL’s structure and interactions between different ions and molecules,which helps us understand the parasitic processes in depth.Simulations demonstrate that water dipole and sulfate ion adsorption at the inner Helmholtz plane drives severe hydrogen evolution and by-product formation.Guided by these insights,we engineered a“water-poor and anion-expelled”EDL using 4,1’,6’-trichlorogalactosucrose(TGS)as an electrolyte additive.As a result,Zn||Zn symmetric cells with TGS exhibited stable cycling for over 4700 h under a current density of 1 mA cm^(−2),while NaV_(3)O_(8)·1.5H_(2)O-based full cells kept 90.4%of the initial specific capacity after 800 cycles at 5 A g^(−1).This work highlights the power of multiscale theoretical frameworks to unravel EDL complexities and guide high-performance ARZB design through integrated theory-experiment approaches.
基金supported by the National Natural Science Foundation of China(Nos.51831007,52101135)the Shenzhen Science and Technology Program,China(No.SGDX20210823104002016)the Guangdong Basic and Applied Basic Research Foundation,China(Nos.2021B1515120071,JCYJ20220531095217039)。
文摘Low-density superalloys often exhibit low yield strength in the intermediate temperature range(300−650℃).To enhance yield performance in this range,the CALPHAD method was used to design a new Co-based superalloy.The Co−30Ni−10Al−3V−6Ti−2Ta alloy,designed based onγʹphase dissolution temperature and phase fraction,was synthesized via arc melting and heat treatment.Phase transition temperatures,microstructure evolution,and hightemperature mechanical properties were characterized by differential scanning calorimetry,scanning electron microscopy,dual-beam TEM,and compression tests.Results show that the alloy has low density(8.15 g/cm^(3))and highγʹdissolution temperature(1234℃),along with unique yield strength retention from room temperature to 650℃.The yield strength anomaly(YSA)is attributed to high stacking fault energy and activation of the Kear−Wilsdorf locking mechanism,contributing to superior high-temperature stability of the alloy.The yield strength of this alloy outperforms other lowdensity Co-based superalloys in the temperature range of 23−650℃.
基金supported by the National Key Research and Development Program of China(Grant No.2024YFA1410300)the National Natural Science Foundation of China(Grant No.12304217)+1 种基金the Natural Science Foundation of Hunan Province(Grant No.2025JJ60002)the Fundamental Research Funds for the Central Universities of China(Grant No.531119200247)。
文摘Moirésuperlattices hosting flat bands and correlated states have become a central focus in condensed matter research.Using first-principles calculations,we investigate three-dimensional flat bands in alternating twisted NbSe_(2)moirébulk structures,which exhibit stronger interlayer interactions than twisted bilayer configurations.Our results show that moirébulks undergo spontaneous large-scale structural relaxation,leading to the formation of remarkably flat energy bands at twist angles≤7.31°.The k_(z)-dependent dispersion of these flat bands across different moirébulks highlights their intrinsic three-dimensional character.Moreover,the presence of out-of-plane mirror symmetry in these moirébulk structures indicates potential interlayer triplet superconducting pairing mechanisms,distinct from those in twisted bilayer systems.This work opens new avenues for exploring three-dimensional flat bands in other moirébulk systems.
基金supported by the National Natural Science Foundation of China (No.52370174)the Natural Science Foundation of Shandong Province,China (No.ZR2022ME128)Special Projects in Key Areas of Colleges and Universities in Guangdong Province (No.2023ZDZX4050)。
文摘The excessive use of pesticides has exacerbated environmental pollution due to herbicide residues,while their persistent toxicity poses serious challenges to global ecological security.A magnetically recyclable CoFe_(2)O_(4)/BiOBr S-scheme heterojunctions was prepared by microwave-assisted co-precipitation method for photocatalytic degradation of Diuron(DUR) in water.The formation of S-scheme heterojunction enhances electron transfer and charge separation,which was demonstrated by free radical trapping,electrochemical experiments,and DFT calculations.The magnetic CoFe_(2)O_(4)/BiOBr catalysts can achieve 99.9 %removal of diuron in 50 min under visible light irradiation.Furthermore,the system maintains stable performance across a broad p H range(3-9),enabling adaptation to diverse water environments,effective elimination of multiple pollutants,and strong resistance to ionic interference.Using magnetic recovery,CoFe_(2)O_(4)/BiOBr exhibits a high removal rate of 99 % and a markedly low ion leaching rate(<20 μg/L) after six cycles photocatalytic process,confirming its excellent stability and durability.According to HPLCQTOF-MS and DFT calculation,the main ways of DUR degradation include dechlorinated hydroxylation,dealkylation and hydroxylation of aromatic ring and side chain.Toxicity analysis showed that the toxicity of the intermediates generated during degradation was generally lower than that of DUR.The magnetic CoFe_(2)O_(4)/BiOBr S-scheme heterojunction developed in this study exhibits excellent photocatalytic performance,high applicability,good stability,and durability,providing an effective magnetic for the removal of refractory pollutants.
基金supported by the National Natural Science Foundation of China (Grant Nos.12325406,92261201,12404305,and W2512072)the Shaanxi Province Natural Science Fundamental Research Project (Grant Nos.2023JC-XJ-03 and23JSQ013)the China Postdoctoral Science Foundation (Grant Nos.BX20240286 and 2024M7625)。
文摘Abiotic oxygen formation predates photosynthesis,sustaining early chemical evolution,yet its elementary mechanisms remain contested.Here,we show the production pathways for molecular oxygen from doubly ionized carbon dioxide upon electron-impact.Through fragment ions and electron coincidence momentum imaging,we unambiguously determine the ionization mechanism by measuring the projectile energy loss in association with the C^(+) +O_(2)^(+) channel.Further potential energy and trajectory calculations enable us to elucidate the dynamical details of this fragmentation process,in which a bond rearrangement pathway is found to proceed via the structural deformation to a triangular intermediate.Moreover,we demonstrate a further roaming pathway for the formation of O_(2)^(+) from CO_(2)^(+) 2,in which a frustrated C-O bond cleavage leaves the O atom without sufficient energy to escape.The O atom then wanders around varied configuration spaces of the flat potential energy regions and forms a C-O-O_(2)^(+) intermediate prior to the final products C^(+) +O_(2)^(+).Considering the large quantities of free electrons in interstellar space,the processes revealed here are expected to be significant and should be incorporated into atmospheric evolution models.
基金supported by the National Natural Science Foundation of China (Grant Nos. 62174019, 52302046, L2424216)the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2024A1515012139)+2 种基金the Major Program (JD) of Hubei Province (Grant No. 2023BAA009)the Knowledge Innovation Program of Wuhan-Shuguang Project (Grant No. 2023010201020262)the Basic Research Program of Jiangsu (Grant No. BK20230268)。
文摘The interfacial properties of Schottky contacts crucially affect the performance of power devices. While a few studies have explored the impact of fluorine on Schottky contacts, a comprehensive theoretical explanation supported by experimental evidence remains lacking. This work investigates the effects of fluorine incorporation and electrothermal annealing(ETA) on the current transport process at Ni/β-Ga_(2)O_(3) Schottky contacts. X-ray photoelectron spectroscopy and first-principles calculations confirm the presence of fluorine substitutions for oxygen and oxygen vacancies and their lowering effect on the Schottky barrier heights. Additionally, accurate electrothermal hybrid TCAD simulations validates the extremely short-duration high temperatures(683 K) induced by ETA, which facilitates lattice rearrangement and reduces interface trap states. The interface trap states are quantitatively resolved through frequency-dependent conductance technique, showing the trap density(DT)reduction from(0.88-2.48) × 10^(11) cm^(-2)·eV^(-1) to(0.46-2.09) × 10^(11) cm^(-2)·eV^(-1). This investigation offers critical insights into the β-Ga_(2)O_(3) contacts with the collaborative treatment and solids the promotion of high-performance β-Ga_(2)O_(3) power devices.
基金supported by the National Key R&D Program of China (Grant No.2022YFA1403201)the National Natural Science Foundation of China (Grant Nos.12125404,T2495231,123B2049,and 12204138)+9 种基金the Advanced MaterialsNational Science and Technology Major Project (Grant No.2024ZD0607000)the Natural Science Foundation of Jiangsu Province (Grant Nos.BK20233001 and BK20253009)the Jiangsu Funding Program for Excellent Postdoctoral Talent (Grant No.2024ZB002)the China Postdoctoral Science Foundation (Grant No.2025M773331)the Fundamental and Interdisciplinary Disciplines Breakthrough Plan of the Ministry of Education of Chinathe AI&AI for Science program of Nanjing UniversityArtificial Intelligence and Quantum physics (AIQ) program of Nanjing Universitythe Fundamental Research Funds for the Central Universitiesthe Natural Science Foundation of Nanjing University of Posts and Telecommunications(Grant Nos.NY224165,NY220038,and NY219087)the Hua Li Talents Program of Nanjing University of Posts and Telecommunications。
文摘We report a theoretical investigation into superconductivity within the MAXH_(6) quaternary hydride system using first-principles calculations,where M and A denote alkali and alkaline earth elements,respectively,and X represents transition metal elements.Systematic analysis of electronic band structures,phonon dispersions,and electron-phonon coupling reveals that substitution of MA binary metal combinations and X metal atoms can create favorable conditions for superconductivity.Mapping of superconducting critical temperatures,combined with dynamical stability analysis through phonon calculations,identifies ten superconducting candidates at ambient pressure.Among these,LiNaAgH_(6) exhibits nearly-free-electron behavior reminiscent of monovalent electron superconductors.It demonstrates exceptional superconducting properties with electron–phonon coupling λ=2.707,which yields a superconducting transition temperature T_(c) of 206.4 K using the Allen–Dynes formula.Its structural analogs MgNaPdH_(6),LiMgPdH_(6),LiMgAgH_(6),LiMgAuH_(6) all exhibit superconducting transition temperatures above 110 K.These findings advance our fundamental understanding of superconductivity in quaternary hydrides and provide guidance for rational design of new high-temperature superconducting materials.
