Electrides,characterized by spatially confined anionic electrons,have emerged as a promising class of materials for catalysis,magnetism,and superconductivity.However,transition-metal-based electrides with diverse elec...Electrides,characterized by spatially confined anionic electrons,have emerged as a promising class of materials for catalysis,magnetism,and superconductivity.However,transition-metal-based electrides with diverse electron dimensionalities remain largely unexplored.Here,we perform a comprehensive first-principles investigation of Y-Co electrides,focusing on Y_(3)Co,Y_(3)Co_(2),and YCo.Our calculations reveal a striking dimensional evolution of anionic electrons:from two-dimensional(2D)confinement in YCo to one-dimensional(1D)in Y_(3)Co_(2)and zero-dimensional(0D)in Y_(3)Co.Remarkably,the YCo monolayer exhibits intrinsic ferromagnetism,with a magnetic moment of 0.65μB per formula unit arising from spin-polarized anionic electrons mediating long-range coupling between Y and Co ions.The monolayer also shows a low exfoliation energy(1.66 J/m^(2)),indicating experimental feasibility.All three electrides exhibit low work functions(2.76 eV-3.11 eV)along with Co-centered anionic states.This work expands the family of transition-metal-based electrides and highlights dimensionality engineering as a powerful strategy for tuning electronic and magnetic properties.展开更多
Electrides are unique ionic compounds that electrons serve as the anions. Many electrides with fascinating physical and chemical properties have been discovered at ambient condition. Under pressure, electrides are als...Electrides are unique ionic compounds that electrons serve as the anions. Many electrides with fascinating physical and chemical properties have been discovered at ambient condition. Under pressure, electrides are also revealed to be ubiquitous crystal morphology, enriching the geometrical topologies and electronic properties of electrides. In this Review,we overview the formation mechanism of high-pressure electrides(HPEs) and outline a scheme for exploring new HPEs from pre-design, CALYPSO assisted structural searches, indicators for electrides, to experimental synthesis. Moreover, the evolution of electronic dimensionality under compression is also discussed to better understand the dimensional distribution of anionic electrons in HPEs.展开更多
In conventional electrides,excess electrons are localized in crystal voids to serve as anions.Most of these electrides are metallic and the metal cations are primarily from the s-block,d-block,or rare-earth elements.H...In conventional electrides,excess electrons are localized in crystal voids to serve as anions.Most of these electrides are metallic and the metal cations are primarily from the s-block,d-block,or rare-earth elements.Here,we report a class of p-block metal-based electrides found in bilayer SnO and PbO,which are semiconducting and feature electride states in both the valence band(VB)and conduction band(CB),as referred to 2D“bipolar”electrides.These bilayers are hybrid electrides where excess electrons are localized in the interlayer region and hybridize with the orbitals of Sn atoms in the VB,exhibiting strong covalent-like interactions with neighboring metal atoms.Compared to previously studied hybrid electrides,the higher electronegativity of Sn and Pb enhances these covalent-like interactions,leading to largely enhanced semiconducting bandgap of up to 2.5 eV.Moreover,the CBM primarily arises from the overlap between metal states and interstitial charges,denoting a potential electride and forming a free-electron-like(FEL)state with small effective mass.This state offers high carrier mobilities for both electron and hole in bilayer SnO,suggesting its potential as a promising p-type semiconductor material.展开更多
Compression of alkali elements makes them depart gradually from the s-band metals,leading to exotic physical and chemical properties.Here,we report the chemical reaction Li+K→Li_(2)K under high pressure by using a sw...Compression of alkali elements makes them depart gradually from the s-band metals,leading to exotic physical and chemical properties.Here,we report the chemical reaction Li+K→Li_(2)K under high pressure by using a swarm intelligence structure searching methodology combined with first-principles calculations.Li_(2)K has three stable/metastable structures and undergoes the pressure-induced phase transitions C2/m→Fddd→I4/mmm at 226 GPa and 291 GPa,respectively.Notably,this system features significant s→p and s→d charge transfers as well as a topologically zerodimensional electride character.Under 300 GPa,Li_(2)K manifests exceptional superconductivity with a critical temperature(T_(c))of 39 K,attributed to the orbital hybridization between Li p states and interstitial quasi-atom-derived s electrons,and their robust coupling with Li and K phonon modes.This work serves as a crucial reference for exploring novel superconducting electrides.展开更多
The Lieb lattice, characterized by its distinctive Dirac cone and flat-band electronic structures, hosts a variety of exotic physical phenomena. However, its realization remains largely confined to artificial lattices...The Lieb lattice, characterized by its distinctive Dirac cone and flat-band electronic structures, hosts a variety of exotic physical phenomena. However, its realization remains largely confined to artificial lattices. In this work, we propose the concept of a Lieb electride, where the non-bound electrons gather at the middle edges,behaving as the quasi-atoms of a Lieb lattice, enabling the emergence of flat bands. Using crystal structure prediction method MAGUS and first-principles calculations, we predict a stable candidate, Ca_(2)I, at ambient pressure. Distinct from conventional electrides with localized electrons at cavity centers, Ca_(2)I features interstitial electrons situated at cavity edges. The resultant flat bands lie close to the Fermi level, giving rise to a pronounced peak in the density of states and leading to Stoner-type ferromagnetism. With increasing pressures, we observe quantum phase transitions from ferromagnetic to non-magnetic and finally to antiferromagnetic orders in Ca_(2)I.Intriguingly, superconductivity emerges in the antiferromagnetic region, suggesting potential competition between these correlated states. Our study not only extends the concepts of electrides but also provides a novel strategy for realizing Lieb lattices through non-bound electrons. This work establishes Ca_(2)I as a promising platform for exploring flat-band physics and correlated electronic states, opening avenues for novel quantum phenomena in electride-based materials.展开更多
Single-atom catalysts(SACs)hold great promise in addressing the sluggish kinetics of the sulfur reduction reaction(SRR)in lithium-sulfur(Li-S)batteries for their unique catalytic activity and maximum atom efficiency.W...Single-atom catalysts(SACs)hold great promise in addressing the sluggish kinetics of the sulfur reduction reaction(SRR)in lithium-sulfur(Li-S)batteries for their unique catalytic activity and maximum atom efficiency.While these SACs must be dispersed on solid substrates,the underlying support is usually limited to carbon materials that have a poor ability to modulate the coordination environment and electronic structures of single atoms,and consequently their catalytic activity toward the SRR is restricted.Here we propose two-dimensional(2D)graphene/electride heterostructu res as substrates to enhance the catalytic activities of SACs for Li-S batteries.2D electrides featuring the anionic electron gas on their surface enable efficient electron transfer to SACs,which alters their electronic structures,resulting in the shifts of the d orbital and Fermi levels.This unique electronic structure decreases the filling of antibonding states such that the bonding with adsorbates at active sites is enhanced.We demonstrate the enhanced catalytic performance of SACs in terms of the Gibbs free energy of SRR and Li_(2)S dissociation.In addition,a universal descriptor for the rapid screening of SACs is established by a linear regression fitting method.This work provides a new design strategy to modulate SAC activity through electrides for Li-S batteries.展开更多
Manipulating the chemical reactivity of graphene toward oxygen reduced reduction(ORR)is of particular interest for both fundamental research and practical application in fuel cell.Deposing graphene on selected substra...Manipulating the chemical reactivity of graphene toward oxygen reduced reduction(ORR)is of particular interest for both fundamental research and practical application in fuel cell.Deposing graphene on selected substrate provides a structure-intact strategy to enhance its chemical reactivity due to substrate-induced charge and interface effect.Here,we report the graphene deposited on one-dimensional electride Y5Si3 as an effective ORR catalyst in acidic media.Thermodynamic calculations suggest that depositing graphene on electride materials can facilitate the protonation of O2,which is the rate-determining step based on the four-electron reaction pathway and thus promote the ORR activity.Further electronic calculations reveal that low work function(3.5 eV),superior electrical conductivity and slight charge transfer from substrate to graphene result in the enhanced ORR performance of graphene.These findings shed light on the rational design of ORR catalysts based on graphitic materials and emphasize the critical role of substrates for energy-related electrochemical reactions.展开更多
Emitter overheating is by far the greatest problem limiting the performance of novel C12A7 hollow cathodes. To explore the failure operating point and degradation mechanism of the C12A7 hollow cathode, microscopic ana...Emitter overheating is by far the greatest problem limiting the performance of novel C12A7 hollow cathodes. To explore the failure operating point and degradation mechanism of the C12A7 hollow cathode, microscopic analyses of a degraded electride emitter after 10 h of thermal electron emission are presented in this paper. The morphology and composition variation of overheated electride emitters by scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction indicate the melting and decomposition of electride of the surface layer. The monitored temperature of the electride emitter during the C12A7 hollow cathode operation shows that to avoid overheating the electride emitter, the average current density allowed should be about 64 m A mm^(-2) for the C12A7 hollow cathode in its current configuration. Experimental results of the heaterless C12A7 hollow cathode demonstrate that xenon(Xe) ion bombardment can remove the insulating layer and restore the thermionic emission capability for less degraded emitters. Based on experimental results and microscopic characterization, the depletion and degradation mechanisms of electride emitters during the hollow cathode operation are discussed.展开更多
To fully realize the superiority of the iodine electric propulsion system in streamlining the size and reducing the operating costs, iodine hollow cathode technology must be developed. Considering the corrosiveness of...To fully realize the superiority of the iodine electric propulsion system in streamlining the size and reducing the operating costs, iodine hollow cathode technology must be developed. Considering the corrosiveness of iodine and the possible impurity of the working propellant, the C12A7 hollow cathode with promising chemical ability was developed and tested. The C12A7 hollow cathode with a nominal current of 1–4 A was successfully ignited with iodine from the reservoir outside the vacuum chamber. It was operated at 1 A of anode current with a 1.2 mg s^(-1) iodine mass flow rate.Despite involuntary extinguishment, the C12A7 hollow cathode could be restarted repeatedly with a single operation time of up to 12 min and a total duration of 30 min. The unexpected fluctuation of iodine flow may be the reason for the short operation time. Experimental results and microscopical observation of the electride emitter show the compatibility of the iodine and electride emitter. For the development and demonstration of future single-iodine electric propulsion of Hall thrusters, the iodine storage and supply system with precise control and regulation may be the critical technology.展开更多
Two-dimensional electride Ca_(2)N has strong electron transfer ability and low work function,which is a potential candidate for hydrogen evolution reaction(HER)catalyst.In this work,based on density functional theory ...Two-dimensional electride Ca_(2)N has strong electron transfer ability and low work function,which is a potential candidate for hydrogen evolution reaction(HER)catalyst.In this work,based on density functional theory calculations,we adopt two strategies to improve the HER catalytic activity of Ca_(2)N monolayer:introducing Ca or N vacancy and doping transition metal atoms(TM,refers to Ti,V,Cr,Mn,Fe,Zr,Nb,Mo,Ru,Hf,Ta and W).Interestingly,the Gibbs free energyΔG_(H*)of Ca_(2)N monolayer after introducing N vacancy is reduced to-0.146 e V,showing good HER catalytic activity.It is highlighted that,the HER catalytic activity of Ca_(2)N monolayer can be further enhanced with TM doping,the Gibbs free energyΔG_(H*)of single Mo and double Mn doped Ca_(2)N are predicted to be 0.119 and 0.139 e V,respectively.The present results will provide good theoretical guidance for the HER catalysis applications of two-dimensional electride Ca_(2)N monolayer.展开更多
Room-temperature superconductivity is predominantly observed in high-pressure hydrides,but faces a formidable hurdle:the tendency of these materials to decompose and forfeit their superconducting prowess upon pressure...Room-temperature superconductivity is predominantly observed in high-pressure hydrides,but faces a formidable hurdle:the tendency of these materials to decompose and forfeit their superconducting prowess upon pressure release.Consequently,stabilizing room-temperature superconductivity under ambient conditions has emerged as a pressing concern in solid-state physics.Electrides are unique compounds,possessing exceptional properties attributed to the clustering of high-energy excess electrons within the interstices of their lattices.Our theory outlines a general blueprint for achieving ambient superconductivity through the strategic insertion of hydrogen into the interstitial spaces of electride materials.This ingenious approach harnesses quasimolecular H_(2)to sequester high-energy electrons,resulting in a substantial density of electronic states at the Fermi level and fostering robust electron-phonon coupling.We implemented this strategy within the realm of alkali metal electrides,finetuning their stability via carrier doping effects,grounded in rigorous quantum chemical analyses of pressure-induced chemical bonds.As a result,the KH_(6)compound exhibits an exceptional superconducting transition temperature of 222 K at a modest 10 GPa,outperforming previously reported high-pressure superconductors like H_(3)S(203 K at 155 GPa)and LaH_(10)(250 K at 170 GPa).Furthermore,the hole-doped NaH_(6)compound demonstrates superconductivity at ambient pressure with a remarkable T_(c)of 167 K,surpassing the previous record-holder HgBa_(2)Ca_(2)Cu_(3)O_(8)with 134 K.展开更多
Paramagnetic LaCoSi,a ternary intermetallic electride,consists of CoSi blocks separated by two layers of La atoms.Its structure is similar to that of the widely studied 111 system of iron-based superconductors.Utilizi...Paramagnetic LaCoSi,a ternary intermetallic electride,consists of CoSi blocks separated by two layers of La atoms.Its structure is similar to that of the widely studied 111 system of iron-based superconductors.Utilizing angle-resolved photoemission spectroscopy and first-principles calculations,we demonstrate the existence of linear bands and flat bands mainly originating from the orbitals of Co 3d states near the Fermi energy.The anomalous scattering rate of the linear bands varies linearly with the binding energy.The flat band above the Fermi energy indicated by the calculations could be modulated by substitutions and pressure to induce new ordered quantum phases,such as magnetism and superconductivity.Our findings reveal flat-band physics in electrides.展开更多
Electrides,in which anionic electrons are trapped in structural cavities,have garnered significant attention for exceptionalfunctionalities based on their low work function.In low-dimensional electrides,a strong quant...Electrides,in which anionic electrons are trapped in structural cavities,have garnered significant attention for exceptionalfunctionalities based on their low work function.In low-dimensional electrides,a strong quantum confinement of anionicelectrons leads to many interesting phenomena,but a severe chemical instability due to their open structures is one of the majordisadvantages for practical applications.Here we report that one-dimensional(1D)dititanium sulfide electride exhibits an ex-traordinary stability originating from the surface self-passivation and consequent durability in bifunctional electrocatalytic activity.Theoretical calculations identify the uniqueness of the 1D[Ti_(2)S]^(2+)·2e^(−)electride,where multiple cavities form two distinct channelstructures of anionic electrons.Combined surface structure analysis and in-situ work function measurement indicate that thenatural formation of amorphous titanium oxide surface layer in air is responsible for the remarkable inertness in water and pH-varied solutions.This makes the[Ti_(2)S]^(2+)·2e^(−)electride an ideal support for a heterogenous metal-electride hybrid catalyst,demonstrating the enhanced efficiency and superior durability in both the hydrogen evolution and oxygen reduction reactionscompared to commercial Pt/C catalysts.This study will stimulate further exploratory research for developing a chemically stableelectride in reactive conditions,evoking a strategy for a practical electrocatalyst for industrial energy conversions.展开更多
基金funding support from the National Science Fund for Distinguished Young Scholars(Grant No.T2225027)the National Natural Science Foundation of China(Grant Nos.12074013 and 12204419)the China Postdoctoral Science Foundation(Grant No.2021M702956)。
文摘Electrides,characterized by spatially confined anionic electrons,have emerged as a promising class of materials for catalysis,magnetism,and superconductivity.However,transition-metal-based electrides with diverse electron dimensionalities remain largely unexplored.Here,we perform a comprehensive first-principles investigation of Y-Co electrides,focusing on Y_(3)Co,Y_(3)Co_(2),and YCo.Our calculations reveal a striking dimensional evolution of anionic electrons:from two-dimensional(2D)confinement in YCo to one-dimensional(1D)in Y_(3)Co_(2)and zero-dimensional(0D)in Y_(3)Co.Remarkably,the YCo monolayer exhibits intrinsic ferromagnetism,with a magnetic moment of 0.65μB per formula unit arising from spin-polarized anionic electrons mediating long-range coupling between Y and Co ions.The monolayer also shows a low exfoliation energy(1.66 J/m^(2)),indicating experimental feasibility.All three electrides exhibit low work functions(2.76 eV-3.11 eV)along with Co-centered anionic states.This work expands the family of transition-metal-based electrides and highlights dimensionality engineering as a powerful strategy for tuning electronic and magnetic properties.
文摘Electrides are unique ionic compounds that electrons serve as the anions. Many electrides with fascinating physical and chemical properties have been discovered at ambient condition. Under pressure, electrides are also revealed to be ubiquitous crystal morphology, enriching the geometrical topologies and electronic properties of electrides. In this Review,we overview the formation mechanism of high-pressure electrides(HPEs) and outline a scheme for exploring new HPEs from pre-design, CALYPSO assisted structural searches, indicators for electrides, to experimental synthesis. Moreover, the evolution of electronic dimensionality under compression is also discussed to better understand the dimensional distribution of anionic electrons in HPEs.
基金the financial support from the Ministry of Science and Technology(MOST)of China(Grant No.2023YFA1406500)the National Natural Science Foundation of China(Grant Nos.11974422 and 12104504)+1 种基金the Fundamental Research Funds for the Central Universities,and the Research Funds of Renmin University of China(Grant No.22XNKJ30)(W.J.)supported by the Outstanding Innovative Talents Cultivation Funded Programs 2023 of Renmin University of China.
文摘In conventional electrides,excess electrons are localized in crystal voids to serve as anions.Most of these electrides are metallic and the metal cations are primarily from the s-block,d-block,or rare-earth elements.Here,we report a class of p-block metal-based electrides found in bilayer SnO and PbO,which are semiconducting and feature electride states in both the valence band(VB)and conduction band(CB),as referred to 2D“bipolar”electrides.These bilayers are hybrid electrides where excess electrons are localized in the interlayer region and hybridize with the orbitals of Sn atoms in the VB,exhibiting strong covalent-like interactions with neighboring metal atoms.Compared to previously studied hybrid electrides,the higher electronegativity of Sn and Pb enhances these covalent-like interactions,leading to largely enhanced semiconducting bandgap of up to 2.5 eV.Moreover,the CBM primarily arises from the overlap between metal states and interstitial charges,denoting a potential electride and forming a free-electron-like(FEL)state with small effective mass.This state offers high carrier mobilities for both electron and hole in bilayer SnO,suggesting its potential as a promising p-type semiconductor material.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12364003,11804131 and 11704163)the Natural Science Foundation of Jiangxi Province of China(Grant Nos.20252BAC240168,20232BAB211022,and 20181BAB211007)the Natural Science Foundation of Henan Province(Grant No.242300421689)。
文摘Compression of alkali elements makes them depart gradually from the s-band metals,leading to exotic physical and chemical properties.Here,we report the chemical reaction Li+K→Li_(2)K under high pressure by using a swarm intelligence structure searching methodology combined with first-principles calculations.Li_(2)K has three stable/metastable structures and undergoes the pressure-induced phase transitions C2/m→Fddd→I4/mmm at 226 GPa and 291 GPa,respectively.Notably,this system features significant s→p and s→d charge transfers as well as a topologically zerodimensional electride character.Under 300 GPa,Li_(2)K manifests exceptional superconductivity with a critical temperature(T_(c))of 39 K,attributed to the orbital hybridization between Li p states and interstitial quasi-atom-derived s electrons,and their robust coupling with Li and K phonon modes.This work serves as a crucial reference for exploring novel superconducting electrides.
基金supported by the National Natural Science Foundation of China(Grant Nos.12125404,T2495231,123B2049,and 12204138)the National Key R&D Program of China(Grant No.2022YFA1403201)+7 种基金the Advanced MaterialsNational Science and Technology Major Project (Grant No.2024ZD0607000)the Basic Research Program of Jiangsu (Grant Nos.BK20233001 and BK20241253)the Jiangsu Funding Program for Excellent Postdoctoral Talent (Grant Nos.2024ZB002,2024ZB075,2025ZB440 and2025ZB852)the China Postdoctoral Science Foundation (Grant No.2025M773331)the Postdoctoral Fellowship Program of CPSF (Grant No.GZC20240695 and GZC20252202)the AI&AI for Science Program of Nanjing UniversityArtificial Intelligence and Quantum physics (AIQ) program of Nanjing Universitythe Fundamental Research Funds for the Central Universities。
文摘The Lieb lattice, characterized by its distinctive Dirac cone and flat-band electronic structures, hosts a variety of exotic physical phenomena. However, its realization remains largely confined to artificial lattices. In this work, we propose the concept of a Lieb electride, where the non-bound electrons gather at the middle edges,behaving as the quasi-atoms of a Lieb lattice, enabling the emergence of flat bands. Using crystal structure prediction method MAGUS and first-principles calculations, we predict a stable candidate, Ca_(2)I, at ambient pressure. Distinct from conventional electrides with localized electrons at cavity centers, Ca_(2)I features interstitial electrons situated at cavity edges. The resultant flat bands lie close to the Fermi level, giving rise to a pronounced peak in the density of states and leading to Stoner-type ferromagnetism. With increasing pressures, we observe quantum phase transitions from ferromagnetic to non-magnetic and finally to antiferromagnetic orders in Ca_(2)I.Intriguingly, superconductivity emerges in the antiferromagnetic region, suggesting potential competition between these correlated states. Our study not only extends the concepts of electrides but also provides a novel strategy for realizing Lieb lattices through non-bound electrons. This work establishes Ca_(2)I as a promising platform for exploring flat-band physics and correlated electronic states, opening avenues for novel quantum phenomena in electride-based materials.
基金financially supported by the National Natural Science Foundation of China (No.22209196 and 12247167)Shandong Province through the Taishan Scholar Programthe Technological Innovation Project (MSTIP) (No.2019JZZY010209)。
文摘Single-atom catalysts(SACs)hold great promise in addressing the sluggish kinetics of the sulfur reduction reaction(SRR)in lithium-sulfur(Li-S)batteries for their unique catalytic activity and maximum atom efficiency.While these SACs must be dispersed on solid substrates,the underlying support is usually limited to carbon materials that have a poor ability to modulate the coordination environment and electronic structures of single atoms,and consequently their catalytic activity toward the SRR is restricted.Here we propose two-dimensional(2D)graphene/electride heterostructu res as substrates to enhance the catalytic activities of SACs for Li-S batteries.2D electrides featuring the anionic electron gas on their surface enable efficient electron transfer to SACs,which alters their electronic structures,resulting in the shifts of the d orbital and Fermi levels.This unique electronic structure decreases the filling of antibonding states such that the bonding with adsorbates at active sites is enhanced.We demonstrate the enhanced catalytic performance of SACs in terms of the Gibbs free energy of SRR and Li_(2)S dissociation.In addition,a universal descriptor for the rapid screening of SACs is established by a linear regression fitting method.This work provides a new design strategy to modulate SAC activity through electrides for Li-S batteries.
基金supported by the National Natural Science Foundation of China (No.21573204 and No.21421063)Ministry of Science and Technology of China (No.2016YFA0200602)+2 种基金Anhui Initiative in Quantum Information Technologies, Fundamental Research Funds for the Central UniversitiesNational Program for Support of Top-notch Young Professional, Chinese Academy of Sciences Interdisciplinary Innovation TeamSuper Computer Center of USTC supercomputing center and CAS supercomputing center
文摘Manipulating the chemical reactivity of graphene toward oxygen reduced reduction(ORR)is of particular interest for both fundamental research and practical application in fuel cell.Deposing graphene on selected substrate provides a structure-intact strategy to enhance its chemical reactivity due to substrate-induced charge and interface effect.Here,we report the graphene deposited on one-dimensional electride Y5Si3 as an effective ORR catalyst in acidic media.Thermodynamic calculations suggest that depositing graphene on electride materials can facilitate the protonation of O2,which is the rate-determining step based on the four-electron reaction pathway and thus promote the ORR activity.Further electronic calculations reveal that low work function(3.5 eV),superior electrical conductivity and slight charge transfer from substrate to graphene result in the enhanced ORR performance of graphene.These findings shed light on the rational design of ORR catalysts based on graphitic materials and emphasize the critical role of substrates for energy-related electrochemical reactions.
基金supported by the Joint Fund for Equipment Pre-research and Aerospace Science and Technology (No. 6141B061203)。
文摘Emitter overheating is by far the greatest problem limiting the performance of novel C12A7 hollow cathodes. To explore the failure operating point and degradation mechanism of the C12A7 hollow cathode, microscopic analyses of a degraded electride emitter after 10 h of thermal electron emission are presented in this paper. The morphology and composition variation of overheated electride emitters by scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction indicate the melting and decomposition of electride of the surface layer. The monitored temperature of the electride emitter during the C12A7 hollow cathode operation shows that to avoid overheating the electride emitter, the average current density allowed should be about 64 m A mm^(-2) for the C12A7 hollow cathode in its current configuration. Experimental results of the heaterless C12A7 hollow cathode demonstrate that xenon(Xe) ion bombardment can remove the insulating layer and restore the thermionic emission capability for less degraded emitters. Based on experimental results and microscopic characterization, the depletion and degradation mechanisms of electride emitters during the hollow cathode operation are discussed.
基金supported by the Joint Fund for Equipment Preresearch and Aerospace Science and Technology (No. 6141B061203)。
文摘To fully realize the superiority of the iodine electric propulsion system in streamlining the size and reducing the operating costs, iodine hollow cathode technology must be developed. Considering the corrosiveness of iodine and the possible impurity of the working propellant, the C12A7 hollow cathode with promising chemical ability was developed and tested. The C12A7 hollow cathode with a nominal current of 1–4 A was successfully ignited with iodine from the reservoir outside the vacuum chamber. It was operated at 1 A of anode current with a 1.2 mg s^(-1) iodine mass flow rate.Despite involuntary extinguishment, the C12A7 hollow cathode could be restarted repeatedly with a single operation time of up to 12 min and a total duration of 30 min. The unexpected fluctuation of iodine flow may be the reason for the short operation time. Experimental results and microscopical observation of the electride emitter show the compatibility of the iodine and electride emitter. For the development and demonstration of future single-iodine electric propulsion of Hall thrusters, the iodine storage and supply system with precise control and regulation may be the critical technology.
基金supported by the National Natural Science Foundation of China(No.21973012)the Natural Science Foundation of Fujian Province(Nos.2020J01474,2021J06011 and 2020J01351)the"Qishan Scholar"Scientific Research Project of Fuzhou University。
文摘Two-dimensional electride Ca_(2)N has strong electron transfer ability and low work function,which is a potential candidate for hydrogen evolution reaction(HER)catalyst.In this work,based on density functional theory calculations,we adopt two strategies to improve the HER catalytic activity of Ca_(2)N monolayer:introducing Ca or N vacancy and doping transition metal atoms(TM,refers to Ti,V,Cr,Mn,Fe,Zr,Nb,Mo,Ru,Hf,Ta and W).Interestingly,the Gibbs free energyΔG_(H*)of Ca_(2)N monolayer after introducing N vacancy is reduced to-0.146 e V,showing good HER catalytic activity.It is highlighted that,the HER catalytic activity of Ca_(2)N monolayer can be further enhanced with TM doping,the Gibbs free energyΔG_(H*)of single Mo and double Mn doped Ca_(2)N are predicted to be 0.119 and 0.139 e V,respectively.The present results will provide good theoretical guidance for the HER catalysis applications of two-dimensional electride Ca_(2)N monolayer.
基金supported by the Research Grants Council of the Hong Kong SAR(Grant No.11317122)City University of Hong Kong(Grant No.9229019)University Research&Development Project of Shenzhen Polytechnic University(Grant No.513-602431Y003P)。
文摘Room-temperature superconductivity is predominantly observed in high-pressure hydrides,but faces a formidable hurdle:the tendency of these materials to decompose and forfeit their superconducting prowess upon pressure release.Consequently,stabilizing room-temperature superconductivity under ambient conditions has emerged as a pressing concern in solid-state physics.Electrides are unique compounds,possessing exceptional properties attributed to the clustering of high-energy excess electrons within the interstices of their lattices.Our theory outlines a general blueprint for achieving ambient superconductivity through the strategic insertion of hydrogen into the interstitial spaces of electride materials.This ingenious approach harnesses quasimolecular H_(2)to sequester high-energy electrons,resulting in a substantial density of electronic states at the Fermi level and fostering robust electron-phonon coupling.We implemented this strategy within the realm of alkali metal electrides,finetuning their stability via carrier doping effects,grounded in rigorous quantum chemical analyses of pressure-induced chemical bonds.As a result,the KH_(6)compound exhibits an exceptional superconducting transition temperature of 222 K at a modest 10 GPa,outperforming previously reported high-pressure superconductors like H_(3)S(203 K at 155 GPa)and LaH_(10)(250 K at 170 GPa).Furthermore,the hole-doped NaH_(6)compound demonstrates superconductivity at ambient pressure with a remarkable T_(c)of 167 K,surpassing the previous record-holder HgBa_(2)Ca_(2)Cu_(3)O_(8)with 134 K.
基金supported by the National Key R&D Program of China(Grant No.2022YFB3608000)the National Natural Science Foundation of China(NSFC)(Grant Nos.12222413 and 12074041)+5 种基金the Natural Science Foundation of Shanghai(Grant Nos.23ZR1482200 and 22ZR1473300)the Funding of Ningbo Yongjiang Talent Program,the Natural Science Foundation of Ningbo,Ningbo University(No.LJ2024003)the Postdoctoral Fellowship Program of CPSF(Grant No.GZC20240951)the Natural Science Foundation of Shandong Province(Grant Nos.ZR2021QA031,ZR2023MA068,and ZR2024QA213)the Qingdao Postdoctoral Project Funding(No.QDBSH20240102115)the Fundamental Research Funds for the Central Universities(Grant No.2243300003).
文摘Paramagnetic LaCoSi,a ternary intermetallic electride,consists of CoSi blocks separated by two layers of La atoms.Its structure is similar to that of the widely studied 111 system of iron-based superconductors.Utilizing angle-resolved photoemission spectroscopy and first-principles calculations,we demonstrate the existence of linear bands and flat bands mainly originating from the orbitals of Co 3d states near the Fermi energy.The anomalous scattering rate of the linear bands varies linearly with the binding energy.The flat band above the Fermi energy indicated by the calculations could be modulated by substitutions and pressure to induce new ordered quantum phases,such as magnetism and superconductivity.Our findings reveal flat-band physics in electrides.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(2022M3H4A1A01010832 and RS-2024-00449682)the Basic Science Research Program through the NRF funded by the Ministry of Education(2021R1A6A1A03039696)+1 种基金Computer time allocation has been provided by the US DOE INCITE program(DE-AC02-06CH11357)National ScienceFoundation ACCESS program(NSF-2138296)。
文摘Electrides,in which anionic electrons are trapped in structural cavities,have garnered significant attention for exceptionalfunctionalities based on their low work function.In low-dimensional electrides,a strong quantum confinement of anionicelectrons leads to many interesting phenomena,but a severe chemical instability due to their open structures is one of the majordisadvantages for practical applications.Here we report that one-dimensional(1D)dititanium sulfide electride exhibits an ex-traordinary stability originating from the surface self-passivation and consequent durability in bifunctional electrocatalytic activity.Theoretical calculations identify the uniqueness of the 1D[Ti_(2)S]^(2+)·2e^(−)electride,where multiple cavities form two distinct channelstructures of anionic electrons.Combined surface structure analysis and in-situ work function measurement indicate that thenatural formation of amorphous titanium oxide surface layer in air is responsible for the remarkable inertness in water and pH-varied solutions.This makes the[Ti_(2)S]^(2+)·2e^(−)electride an ideal support for a heterogenous metal-electride hybrid catalyst,demonstrating the enhanced efficiency and superior durability in both the hydrogen evolution and oxygen reduction reactionscompared to commercial Pt/C catalysts.This study will stimulate further exploratory research for developing a chemically stableelectride in reactive conditions,evoking a strategy for a practical electrocatalyst for industrial energy conversions.
