We propose an experimentally feasible scheme for preparing a four-atom cluster state in a thermal cavity. In the scheme, the cavity field is only virtually excited and the photon-number-dependent part in the effective...We propose an experimentally feasible scheme for preparing a four-atom cluster state in a thermal cavity. In the scheme, the cavity field is only virtually excited and the photon-number-dependent part in the effective Hamiltonian is cancelled so that the system is insensitive to the cavity decay and the thermal field. At the same time, the scheme can be generalized to prepare n-atom cluster states with the success probability 100%. In addition, using the four-atom cluster state, we also propose a simpler scheme for implementing a remote-controlled not gate （CNOT） without the Bell states measurement.展开更多
This paper proposes two schemes to generate the multi-atom cluster states. The first scheme is based on the interaction of atoms with a highly detuned cavity mode and a classical field, the second scheme is based on t...This paper proposes two schemes to generate the multi-atom cluster states. The first scheme is based on the interaction of atoms with a highly detuned cavity mode and a classical field, the second scheme is based on the interaction of atoms with a cavity mode, strongly driven by a resonant classical field.展开更多
Ordering and atom clustering in aging binary Al-Li alloy has been investigated by computer simulation through calculating the long range order (Iro.) parameter and composition deviation order parameter from single-sit...Ordering and atom clustering in aging binary Al-Li alloy has been investigated by computer simulation through calculating the long range order (Iro.) parameter and composition deviation order parameter from single-site occupation probabilities of Li atom. The results show that when the alloy lies in metastable region in the phase diagram ordering and atom clustering occur simultaneously. As the composition of the alloy increases ordering occurs earlier than atom clustering gradually. When the alloy lies in instable region atom clustering takes place after the congruent ordering completes. It has also been found that the incubation period of the phase transformation is shortened as the composition increases.展开更多
Regulating the electronic structure and oxygencontaining intermediates adsorption behavior on Fe-based catalysts is of great significance to cope with the sluggish oxygen reduction reaction(ORR)kinetics,but it still r...Regulating the electronic structure and oxygencontaining intermediates adsorption behavior on Fe-based catalysts is of great significance to cope with the sluggish oxygen reduction reaction(ORR)kinetics,but it still remains a great challenge.In this work,Fe atom clusters(Fe_(AC))modified by high-density Cu single atoms(Cu_(SA))in a N,S-doped porous carbon substrate(Fe_(AC)/Cu_(SA)@NCS)is reported for enhanced ORR electrocatalysis.Fe_(AC)/Cu_(SA)@NCS exhibits excellent ORR performance with a half-wave potential(E_(1/2))of 0.911 V,a high four-electron process selectivity and excellent stability.The ORR performance is also verified in the Fe_(AC)/Cu_(SA)@NCS-based Zn-air battery,which shows a high peak power density of 192.67 mW cm^(-2),a higher specific capacity of 808.3 mAh g^(-1)and impressive charge-discharge cycle stability.Moreover,density functional theory calculations show that Cu single atoms synergistically modulate the electronic structure Fe active atoms in Fe atomic clusters,reducing the energy barrier of the rate-determining step(i.e.,*OH desorption)on Fe_(AC)/Cu_(SA)@NCS.This work provides an effective way to regulate the electronic structure of Fe-based catalysts and optimize their electrocatalytic activity based on the introduction of a second metal source.展开更多
As an important basic raw material,acetic acid has broad application prospects in industrial production[1].However,traditional synthetic methods for acetic acid mainly rely on fossil fuels[2].High-temperature and high...As an important basic raw material,acetic acid has broad application prospects in industrial production[1].However,traditional synthetic methods for acetic acid mainly rely on fossil fuels[2].High-temperature and high-pressure reaction processes not only lead to a serious energy crisis,but also sharpen the emission of greenhouse gases[3],which is not conducive to the effective implementation of sustainable development strategies.展开更多
Atomically precise palladium(Pd)clusters are emerging as versatile nanomaterials with applications in catalysis and biomedicine.This study explores the synthesis,structure evolution,and catalytic properties of Pd clus...Atomically precise palladium(Pd)clusters are emerging as versatile nanomaterials with applications in catalysis and biomedicine.This study explores the synthesis,structure evolution,and catalytic properties of Pd clusters stabilized by cyclohexanethiol(HSC_(6)H_(11))ligands.Using electrospray ionization mass spectrometry(ESI-MS)and single-crystal X-ray diffraction(SXRD),structures of the Pd clusters ranging from Pd4(SC_(6)H_(11))8 to Pd18(SC_(6)H_(11))36 were determined.This analysis revealed a structure evolution from polygonal to elliptical geometries of the PdnS2n frameworks as the cluster size increased.UV-Vis-NIR spectroscopy,combined with quantum chemical calculations,elucidated changes in the electronic structure of the clusters.Catalytic studies on the Sonogashira cross-coupling reactions demonstrated a size-dependent decline in activity attributed to variations in structural arrangements and electronic properties.Mechanistic insights proposed a distinctive Pd(Ⅱ)-Pd(Ⅳ)catalytic cycle.This research underscores how ligands and cluster size influence the structures and properties of Pd clusters,offering valuable insights for the future design and application of Pd clusters in advanced catalysis and beyond.展开更多
The reactions of anionic zirconium oxide clusters ZrxOy- with C2H6 and C4H10 are investi-gated by a time of flight mass spectrometer coupled with a laser vaporization cluster source.Hydrogen containing products Zr2O5H...The reactions of anionic zirconium oxide clusters ZrxOy- with C2H6 and C4H10 are investi-gated by a time of flight mass spectrometer coupled with a laser vaporization cluster source.Hydrogen containing products Zr2O5H- and Zr3O7H- are observed after the reaction. Den-sity functional theory calculations indicate that the hydrogen abstraction is favorable in the reaction of Zr2O5- with C2H6, which supports that the observed Zr2O5H- and Zr3O7H- are due to hydrogen atom abstraction from the alkane molecules. This work shows a newpossible pathway in the reaction of zirconium oxide cluster anions with alkane molecules.展开更多
This paper proposes a scheme for implementing the teleportation of an arbitrary unknown two-atom state by using a cluster state of four identical 2-level atoms as quantum channel in a thermal cavity. The two distinct ...This paper proposes a scheme for implementing the teleportation of an arbitrary unknown two-atom state by using a cluster state of four identical 2-level atoms as quantum channel in a thermal cavity. The two distinct advantages of the present scheme are： （i） The discrimination of 16 orthonormal cluster states in the standard teleportation protocol is transformed into the discrimination of single-atom states. Consequently, the discrimination difficulty of states is degraded. （ii） The scheme is insensitive to the cavity field state and the cavity decay for the thermal cavity is only virtually excited when atoms interact with it. Thus, the scheme is more feasible.展开更多
Environment-friendly energy storage and conversion technologies,such as metal-air batteries and fuel cells,are considered promising approaches to address growing environmental concerns.The oxygen reduction reaction(OR...Environment-friendly energy storage and conversion technologies,such as metal-air batteries and fuel cells,are considered promising approaches to address growing environmental concerns.The oxygen reduction reaction(ORR)is the core of renewable energy conversion technology and plays an irreplaceable role in this fundamental issue.However,the complex multi-reaction process of the ORR presents a bottleneck that limits efforts to accelerate its kinetics.Traditionally,Pt and Pt-based catalysts are regarded as a good choice to improve the sluggish kinetics of the ORR.However,because Pt-based catalysts are expensive and have low durability,their use to resolve the energy crisis and current environmental challenges is impractical.Hence,exploring low-cost,highly active,and durable ORR catalysts as potential alternatives to commercial Pt/C is an urgent undertaking.Atomic cluster catalysts(ACCs)may be suitable alternatives to commercial Pt/C catalysts owing to their ultra-high atomic utilization efficiency,unique electronic structure,and stable nanostructures.However,despite the significant progress achieved in recent years,ACCs remain unusable for practical applications.In this study,a facile plasma bombing method combined with an acid washing strategy is proposed to fabricate an atomic Co cluster-decorated porous carbon supports catalyst(CoAC/NC)showing improved ORR performance.The typical atomic cluster features of the resultant CoAC/NC catalyst are confirmed using comprehensive characterization techniques.The CoAC/NC catalyst exhibits considerable ORR activity with a half-wave potential of as high as 0.887 V(versus a reversible hydrogen electrode(RHE)),which is much higher than that of a commercial Pt/C catalyst.More importantly,the CoAC/NC catalyst displays excellent battery performance when applied to a Zn-air battery,showing a peak power density of 181.5 mW·cm^(-2)and long discharge ability(over 67 h at a discharge current density of 5 mA·cm^(-2)).The desirable ORR performance of the fabricated CoAC/NC catalyst could be mainly attributed to the high atom utilization efficiency and stable active sites endowed by the unique Co atomic clusters,as well as synergistic effects between the neighboring Co atoms of these clusters.Moreover,the high specific surface area and wide pore distribution of the catalyst offer abundant accessible active sites for the ORR.This work not only provides an outstanding alternative to commercial Pt catalysts for the ORR but also offers new insights into the rational design and practical application of ACCs.展开更多
Palladium(Pd)‐based catalysts are essential to drive high‐performance Suzuki coupling reactions,which are powerful tools for the synthesis of functional organic compounds.Herein,we developed a solution‐rapid‐annea...Palladium(Pd)‐based catalysts are essential to drive high‐performance Suzuki coupling reactions,which are powerful tools for the synthesis of functional organic compounds.Herein,we developed a solution‐rapid‐annealing process to stabilize nitrogen‐mesoporous carbon supported Pd single‐atom/cluster(Pd/NMC)material,which provided a catalyst with superior performance for Suzuki coupling reactions.In comparison with commercial palladium/carbon(Pd/C)catalysts,the Pd/NMC catalyst exhibited significantly boosted activity(100%selectivity and 95%yield)and excellent stability(almost no decay in activity after 10 reuse cycles)for the Suzuki coupling reactions of chlorobenzenes,together with superior yield and excellent selectivity in the fields of the board scope of the reactants.Moreover,our newly developed rapid annealing process of precursor solutions is applied as a generalized method to stabilize metal clusters(e.g.Pd,Pt,Ru),opening new possibilities in the construction of efficient highly dispersed metal atom and sub‐nanometer cluster catalysts with high performance.展开更多
Heterogeneous catalysts with ultra-small clusters and atomically dispersed(USCAD)active sites have gained increasing attention in recent years.However,developing USCAD catalysts with high-density metal sites anchored ...Heterogeneous catalysts with ultra-small clusters and atomically dispersed(USCAD)active sites have gained increasing attention in recent years.However,developing USCAD catalysts with high-density metal sites anchored in porous nanomaterials is still challenging.Here,through the template-free S-assisted pyrolysis of low-cost Fe-salts with melamine(MA),porous alveolate Fe/g-C3N4 catalysts with high-density(Fe loading up to 17.7 wt%)and increased USCAD Fe sites were synthesized.The presence of a certain amount of S species in the Fe-salts/MA system plays an important role in the formation of USCAD S-Fe-salt/CN catalysts;the S species act as a"sacrificial carrier"to increase the dispersion of Fe species through Fe-S coordination and generate porous alveolate structure by escaping in the form of SO2 during pyrolysis.The S-Fe-salt/CN catalysts exhibit greatly promoted activity and reusability for degrading various organic pollutants in advanced oxidation processes compared to the corresponding Fe-salt/CN catalysts,due to the promoted accessibility of USCAD Fe sites by the porous alveolate structure.This S-assisted method exhibits good feasibility in a large variety of S species(thiourea,S powder,and NH4SCN)and Fe salts,providing a new avenue for the low-cost and large-scale synthesis of high-density USCAD metal/g-C3N4 catalysts.展开更多
Three-dimensional distribution of solute elements in an Mg–Zn–Gd alloy during ageing process is quantitatively characterized by three-dimensional atom probe(3DAP) tomography. Based on the radius distribution functio...Three-dimensional distribution of solute elements in an Mg–Zn–Gd alloy during ageing process is quantitatively characterized by three-dimensional atom probe(3DAP) tomography. Based on the radius distribution function, it is found that Zn–Gd solute pairs in Mg matrix appear mainly at two peaks at early stage of ageing, and the separation distance between Zn and Gd atoms could be well rationalized by the first-principle calculation. Moreover, the fraction of Zn–Gd solute pairs increases first and then decreases due to the precipitation of long-period stacking ordered(LPSO) structures. Both the composition of the structural unit in LPSO structure and the solute enrichment around it are quantified. It is found that Zn and Gd elements are synchronized in the LPSO structure, and solute segregation of pure Zn or Gd is not observed at the transformation front of the LPSO structure in this alloy. In addition, the crystallography of transformation front is further determined by 3DAP data.展开更多
A condition for local moment formation in metals derived by Stoddart and March (Ann. Phys. NY 1972 64, 174) is first used to discuss the ferromagnetism of body-centred-cubic Fe. A less detailed discussion is also ...A condition for local moment formation in metals derived by Stoddart and March (Ann. Phys. NY 1972 64, 174) is first used to discuss the ferromagnetism of body-centred-cubic Fe. A less detailed discussion is also added on Ni and Co. This leads into a treatment of the non- linear response of such 3d ferromagnets to dilute substitutional impurities. Antiferromagnets responding to local changes in the exchange field caused by such impurities are also studied, Mn in Cr being one such system discussed. The paper concludes with a brief summary of clusters of transition metal atoms, with most attention devoted to Cr and to Mn.展开更多
The interaction between intense femtosecond laser pulses and hydrogen atomic clusters is studied by a simplified Coulomb explosion model. The dependences of average proton kinetic energy on cluster size, pulse duratio...The interaction between intense femtosecond laser pulses and hydrogen atomic clusters is studied by a simplified Coulomb explosion model. The dependences of average proton kinetic energy on cluster size, pulse duration, laser intensity and wavelength are studied respectively. The calculated results indicate that the irradiation of a femtosecond laser of longer wavelength on hydrogen atomic clusters may be a simple, economical way to produce highly kinetic hydrogen ions. The phenomenon suggests that the irradiation of femtosecond laser of longer wavelength on deuterium atomic clusters may be easier than that of shorter wavelength to drive nuclear fusion reactions. The product of the laser intensity and the squared laser wavelength needed to make proton energy saturated as a function of the squared cluster radius is also investigated. The proton energy distribution calculated is also shown and compared with the experimental data. Our results are in agreement with the experimental results fairly well.展开更多
Ionization potentials and electron affinities of Cux (n = 2-7) atomic clusters with the optimal geom etries have been calculated by use of SC F-Xa-SW method and Slater's transition state theory. Theo retical calc...Ionization potentials and electron affinities of Cux (n = 2-7) atomic clusters with the optimal geom etries have been calculated by use of SC F-Xa-SW method and Slater's transition state theory. Theo retical calcuIations show that the ionization potentiaIs and electron affinities of Cu. (n = 2-7) atom ic clusters have a sharp even / odd alternation with increasing their sizes, which are related to the electronic structure of Cun atomic clusters. The theoretical results are consistent with the related ex perimental ones.展开更多
A novel Ni-Cr-Si-B filler metal with the cluster formula of[Cr-Ni12]B2Cr+[B-Ni8Cr]BSi Cr based on the cluster-plus-glue-atom model was designed for vacuum brazing GH4169 alloy.The effect of brazing temperature and bra...A novel Ni-Cr-Si-B filler metal with the cluster formula of[Cr-Ni12]B2Cr+[B-Ni8Cr]BSi Cr based on the cluster-plus-glue-atom model was designed for vacuum brazing GH4169 alloy.The effect of brazing temperature and brazing time on microstructure and shear strength of GH4169 alloy joints was investigated.The brazed seam was mainly composed ofγ-Ni solid solution.(Nb,Ti)-rich phase and(Cr,Nb,Mo)-rich borides distributed in diffusion zones.The diffusion and aggregation of B,Cr,Nb,and Mo resulted in the variation of phase contrast and morphology of borides.Coarse precipitations in the joint brazed at1240℃consisted of borides,Laves phase andδphase.The shear strength of joints was principally dominated by the brittle precipitations in diffusion zone,and the homogenization of microstructure improved the room-temperature shear strength to 820 MPa with the high-temperature shear strength of 627 MPa for the joint brazed at 1240℃/20 min.The joint fractured in diffusion zone and brazed seam,and the existence of borides and Laves phase in diffusion zone provide the potential origin for crack growth.展开更多
We exploited a hydrogen-passivated germanium atomic cluster（Ge10H16） as a model to study the mechanism of lithium alloying with germanium. Based on the density functional theory, the electronic and crystal structure...We exploited a hydrogen-passivated germanium atomic cluster（Ge10H16） as a model to study the mechanism of lithium alloying with germanium. Based on the density functional theory, the electronic and crystal structures of lithium-alloyed Ge10H16 were investigated. The theoretical results indicate that the alloying of lithium with Ge10H16 will weaken the germanium-hydrogen bond and repel the closest germanium atom away from the alloyed lithium atom. Based on the maps of the electron density distribution, the nature of the lithium-germanium chemical bond was analyzed. Moreover, the diffusion process of the lithium on the Ge10H16 cluster was detected, which suggested that there is a close relationship between the diffusion barriers and the coordination number around the lithium atom.展开更多
This paper tries to outline the influence of atomic mobility on the initial fabrication of thin films formed by LECBD. Based on our recent studies on low-energy cluster beam deposition (LECBD) by molecular dynamics si...This paper tries to outline the influence of atomic mobility on the initial fabrication of thin films formed by LECBD. Based on our recent studies on low-energy cluster beam deposition (LECBD) by molecular dynamics simulation, two examples, the deposition of small carbon clusters on Si and diamond surfaces and Al clusters on Ni substrate, were mainly discussed. The impact energy of the cluster ranges from 0.1 eV to 100 eV. In the former case, the mobility and the lateral migration of surface atoms, especially the recoil atoms, are enhanced with increasing the impact energy, which promote the film to be smoother and denser. For the latter case, the transverse kinetic energy of cluster atoms, caused mainly by the collision between moving cluster atoms, dominates the lateral spread of cluster atoms on the surface, which is contributive to layer-by-layer growth of thin films. Our result is consistent with the experimental observations that the film structure is strongly dependent on the impact energy. In addition, it elucidates that the atomic mobility takes a leading role in the structure characteristic of films formed by LECBD.展开更多
Constructing the desired long-range dual sites to enhance the C–C bond-cleavage and CO-tolerate ability during ethanol oxidation reaction is of importance for further applications.Herein,the concept of holding atomic...Constructing the desired long-range dual sites to enhance the C–C bond-cleavage and CO-tolerate ability during ethanol oxidation reaction is of importance for further applications.Herein,the concept of holding atomically dispersed NiO_(x)cluster supported on Pt-based high-index facets(NiO_(x)/Pt)is proposed to build O-bridged Pt–Ni dual sites.Strikingly,the obtained NiO_(x)/Pt dual sites show 4.97 times specific activity higher than that of commercial Pt/C(0.35 mA cm^(-2)),as well as outstanding CO-tolerance and durability.The advanced electrochemical in-situ characterizations reveal that the NiO_(x)/Pt can accelerate rapid dehydroxylation and C–C bondcleavage over the Pt–Ni dual sites.Theoretical calculations disclose that the atomically dispersed NiO_(x)species can lower the adsorption/reaction energy barriers of intermediates.This tactic provides a promising methodology on regulating the surface synergistic sites via engineering atomically dispersed oxide site.展开更多
Nanometer-sized metal clusters were prepared inside single crystalline MgO films by vacuum co-deposition of metals and MgO. The atomic structure was studied by high-resolution electron microscopy (HREM) and nm-area el...Nanometer-sized metal clusters were prepared inside single crystalline MgO films by vacuum co-deposition of metals and MgO. The atomic structure was studied by high-resolution electron microscopy (HREM) and nm-area electron diffraction. The size of the clusters is ranging from 1 nm to 3 nm without those larger than 5 nm, and most of them have definite epitaxial orientations with the MgO matrix films. The character of the composite films is very much useful for the studies of various kinds of physical properties with anisotroPy. The physical properties such as electric transport, magnetic, optical absorption, sintering and catalytic ones were thus measured on the same samples analyzed by HREM by using high sensitivity apparatus with interest of clarifying the retationship between the atomic structure and physical properties展开更多
基金Project supported by the National Natural Science Foundation （Grant No 10574022）, and the Funds of the Natural Science of Fujian Province, China （Grant No Z0512006）.
文摘We propose an experimentally feasible scheme for preparing a four-atom cluster state in a thermal cavity. In the scheme, the cavity field is only virtually excited and the photon-number-dependent part in the effective Hamiltonian is cancelled so that the system is insensitive to the cavity decay and the thermal field. At the same time, the scheme can be generalized to prepare n-atom cluster states with the success probability 100%. In addition, using the four-atom cluster state, we also propose a simpler scheme for implementing a remote-controlled not gate （CNOT） without the Bell states measurement.
文摘This paper proposes two schemes to generate the multi-atom cluster states. The first scheme is based on the interaction of atoms with a highly detuned cavity mode and a classical field, the second scheme is based on the interaction of atoms with a cavity mode, strongly driven by a resonant classical field.
文摘Ordering and atom clustering in aging binary Al-Li alloy has been investigated by computer simulation through calculating the long range order (Iro.) parameter and composition deviation order parameter from single-site occupation probabilities of Li atom. The results show that when the alloy lies in metastable region in the phase diagram ordering and atom clustering occur simultaneously. As the composition of the alloy increases ordering occurs earlier than atom clustering gradually. When the alloy lies in instable region atom clustering takes place after the congruent ordering completes. It has also been found that the incubation period of the phase transformation is shortened as the composition increases.
基金financially supported by the National Natural Science Foundation of China(No.22278042)the National Natural Science Foundation of Jiangsu Province(No.BK20240567)+2 种基金the Introduction and Cultivation of Leading Innovative Talents Foundation of Changzhou,Jiangsu Province(No.CQ20220093)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.24KJD530001)the Open Project Program of Key Laboratory of Optic-electric Sensing and Analytical Chemistry for Life Science(No.M2024-7),MOE
文摘Regulating the electronic structure and oxygencontaining intermediates adsorption behavior on Fe-based catalysts is of great significance to cope with the sluggish oxygen reduction reaction(ORR)kinetics,but it still remains a great challenge.In this work,Fe atom clusters(Fe_(AC))modified by high-density Cu single atoms(Cu_(SA))in a N,S-doped porous carbon substrate(Fe_(AC)/Cu_(SA)@NCS)is reported for enhanced ORR electrocatalysis.Fe_(AC)/Cu_(SA)@NCS exhibits excellent ORR performance with a half-wave potential(E_(1/2))of 0.911 V,a high four-electron process selectivity and excellent stability.The ORR performance is also verified in the Fe_(AC)/Cu_(SA)@NCS-based Zn-air battery,which shows a high peak power density of 192.67 mW cm^(-2),a higher specific capacity of 808.3 mAh g^(-1)and impressive charge-discharge cycle stability.Moreover,density functional theory calculations show that Cu single atoms synergistically modulate the electronic structure Fe active atoms in Fe atomic clusters,reducing the energy barrier of the rate-determining step(i.e.,*OH desorption)on Fe_(AC)/Cu_(SA)@NCS.This work provides an effective way to regulate the electronic structure of Fe-based catalysts and optimize their electrocatalytic activity based on the introduction of a second metal source.
基金financially supported by the Key Grant for Special Professors in Jiangsu Province(No.RK119STP23002)the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(No.NY223016)+2 种基金2024 Nanjing Science and Technology Innovation Program(No.NJKCZYZZ2024-06)the Project of State Key Laboratory of Organic Electronics and Information Displays,Nanjing University of Posts and Telecommunication(Nos.ZS030ZR24004 and ZS030ZR23034)the“Belt and Road”Innovation Cooperation Project of Jiangsu(No.BZ2022011).
文摘As an important basic raw material,acetic acid has broad application prospects in industrial production[1].However,traditional synthetic methods for acetic acid mainly rely on fossil fuels[2].High-temperature and high-pressure reaction processes not only lead to a serious energy crisis,but also sharpen the emission of greenhouse gases[3],which is not conducive to the effective implementation of sustainable development strategies.
基金supported by the Start-Up Research Funding of Fujian Normal University(No.Y0720326K13)the National Natural Science Foundation of China(Nos.22103035 and 22033005)+2 种基金the National Key R&D Program of China(No.2022YFA1503900)Shenzhen Science and Technology Program(No.RCYX20231211090357078)Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002).
文摘Atomically precise palladium(Pd)clusters are emerging as versatile nanomaterials with applications in catalysis and biomedicine.This study explores the synthesis,structure evolution,and catalytic properties of Pd clusters stabilized by cyclohexanethiol(HSC_(6)H_(11))ligands.Using electrospray ionization mass spectrometry(ESI-MS)and single-crystal X-ray diffraction(SXRD),structures of the Pd clusters ranging from Pd4(SC_(6)H_(11))8 to Pd18(SC_(6)H_(11))36 were determined.This analysis revealed a structure evolution from polygonal to elliptical geometries of the PdnS2n frameworks as the cluster size increased.UV-Vis-NIR spectroscopy,combined with quantum chemical calculations,elucidated changes in the electronic structure of the clusters.Catalytic studies on the Sonogashira cross-coupling reactions demonstrated a size-dependent decline in activity attributed to variations in structural arrangements and electronic properties.Mechanistic insights proposed a distinctive Pd(Ⅱ)-Pd(Ⅳ)catalytic cycle.This research underscores how ligands and cluster size influence the structures and properties of Pd clusters,offering valuable insights for the future design and application of Pd clusters in advanced catalysis and beyond.
基金This work was supported by the Chinese Academy of Sciences （Hundred Talents Fund）, the National Natural Science Foundation of China （No.20703048 and No.20803083）, and the Center of Molecular Science Foundation of Institute of Chemistry, Chinese Academy of Sciences （No.CMS-LX200902）.
文摘The reactions of anionic zirconium oxide clusters ZrxOy- with C2H6 and C4H10 are investi-gated by a time of flight mass spectrometer coupled with a laser vaporization cluster source.Hydrogen containing products Zr2O5H- and Zr3O7H- are observed after the reaction. Den-sity functional theory calculations indicate that the hydrogen abstraction is favorable in the reaction of Zr2O5- with C2H6, which supports that the observed Zr2O5H- and Zr3O7H- are due to hydrogen atom abstraction from the alkane molecules. This work shows a newpossible pathway in the reaction of zirconium oxide cluster anions with alkane molecules.
基金supported by the Program for New Century Excellent Talents at the University of China (Grant No NCET-06-0554)the National Natural Science Foundation of China (Grant Nos 60677001 and 10747146)+3 种基金the Science-Technology Fund of AnhuiProvince for Outstanding Youth of China (Grant No 06042087)the Key Fund of the Ministry of Education of China (Grant No 206063)the Natural Science Foundation of Guangdong Province of China (Grant Nos 06300345 and 7007806)Natural Science Foundation of Hubei Province of China (Grant No 2006ABA354)
文摘This paper proposes a scheme for implementing the teleportation of an arbitrary unknown two-atom state by using a cluster state of four identical 2-level atoms as quantum channel in a thermal cavity. The two distinct advantages of the present scheme are： （i） The discrimination of 16 orthonormal cluster states in the standard teleportation protocol is transformed into the discrimination of single-atom states. Consequently, the discrimination difficulty of states is degraded. （ii） The scheme is insensitive to the cavity field state and the cavity decay for the thermal cavity is only virtually excited when atoms interact with it. Thus, the scheme is more feasible.
文摘Environment-friendly energy storage and conversion technologies,such as metal-air batteries and fuel cells,are considered promising approaches to address growing environmental concerns.The oxygen reduction reaction(ORR)is the core of renewable energy conversion technology and plays an irreplaceable role in this fundamental issue.However,the complex multi-reaction process of the ORR presents a bottleneck that limits efforts to accelerate its kinetics.Traditionally,Pt and Pt-based catalysts are regarded as a good choice to improve the sluggish kinetics of the ORR.However,because Pt-based catalysts are expensive and have low durability,their use to resolve the energy crisis and current environmental challenges is impractical.Hence,exploring low-cost,highly active,and durable ORR catalysts as potential alternatives to commercial Pt/C is an urgent undertaking.Atomic cluster catalysts(ACCs)may be suitable alternatives to commercial Pt/C catalysts owing to their ultra-high atomic utilization efficiency,unique electronic structure,and stable nanostructures.However,despite the significant progress achieved in recent years,ACCs remain unusable for practical applications.In this study,a facile plasma bombing method combined with an acid washing strategy is proposed to fabricate an atomic Co cluster-decorated porous carbon supports catalyst(CoAC/NC)showing improved ORR performance.The typical atomic cluster features of the resultant CoAC/NC catalyst are confirmed using comprehensive characterization techniques.The CoAC/NC catalyst exhibits considerable ORR activity with a half-wave potential of as high as 0.887 V(versus a reversible hydrogen electrode(RHE)),which is much higher than that of a commercial Pt/C catalyst.More importantly,the CoAC/NC catalyst displays excellent battery performance when applied to a Zn-air battery,showing a peak power density of 181.5 mW·cm^(-2)and long discharge ability(over 67 h at a discharge current density of 5 mA·cm^(-2)).The desirable ORR performance of the fabricated CoAC/NC catalyst could be mainly attributed to the high atom utilization efficiency and stable active sites endowed by the unique Co atomic clusters,as well as synergistic effects between the neighboring Co atoms of these clusters.Moreover,the high specific surface area and wide pore distribution of the catalyst offer abundant accessible active sites for the ORR.This work not only provides an outstanding alternative to commercial Pt catalysts for the ORR but also offers new insights into the rational design and practical application of ACCs.
文摘Palladium(Pd)‐based catalysts are essential to drive high‐performance Suzuki coupling reactions,which are powerful tools for the synthesis of functional organic compounds.Herein,we developed a solution‐rapid‐annealing process to stabilize nitrogen‐mesoporous carbon supported Pd single‐atom/cluster(Pd/NMC)material,which provided a catalyst with superior performance for Suzuki coupling reactions.In comparison with commercial palladium/carbon(Pd/C)catalysts,the Pd/NMC catalyst exhibited significantly boosted activity(100%selectivity and 95%yield)and excellent stability(almost no decay in activity after 10 reuse cycles)for the Suzuki coupling reactions of chlorobenzenes,together with superior yield and excellent selectivity in the fields of the board scope of the reactants.Moreover,our newly developed rapid annealing process of precursor solutions is applied as a generalized method to stabilize metal clusters(e.g.Pd,Pt,Ru),opening new possibilities in the construction of efficient highly dispersed metal atom and sub‐nanometer cluster catalysts with high performance.
文摘Heterogeneous catalysts with ultra-small clusters and atomically dispersed(USCAD)active sites have gained increasing attention in recent years.However,developing USCAD catalysts with high-density metal sites anchored in porous nanomaterials is still challenging.Here,through the template-free S-assisted pyrolysis of low-cost Fe-salts with melamine(MA),porous alveolate Fe/g-C3N4 catalysts with high-density(Fe loading up to 17.7 wt%)and increased USCAD Fe sites were synthesized.The presence of a certain amount of S species in the Fe-salts/MA system plays an important role in the formation of USCAD S-Fe-salt/CN catalysts;the S species act as a"sacrificial carrier"to increase the dispersion of Fe species through Fe-S coordination and generate porous alveolate structure by escaping in the form of SO2 during pyrolysis.The S-Fe-salt/CN catalysts exhibit greatly promoted activity and reusability for degrading various organic pollutants in advanced oxidation processes compared to the corresponding Fe-salt/CN catalysts,due to the promoted accessibility of USCAD Fe sites by the porous alveolate structure.This S-assisted method exhibits good feasibility in a large variety of S species(thiourea,S powder,and NH4SCN)and Fe salts,providing a new avenue for the low-cost and large-scale synthesis of high-density USCAD metal/g-C3N4 catalysts.
基金supported by a Grant-in-Aid for Scientific Research on Innovative Areas,‘‘Synchronized Long-Period Stacking Ordered Structure’’,from the Ministry of Education,Culture,Sports,Science and Technology,Japan(No.23109006)Fundamental Research Funds for the Central Universities(No.FRFTP-17-003A1)
文摘Three-dimensional distribution of solute elements in an Mg–Zn–Gd alloy during ageing process is quantitatively characterized by three-dimensional atom probe(3DAP) tomography. Based on the radius distribution function, it is found that Zn–Gd solute pairs in Mg matrix appear mainly at two peaks at early stage of ageing, and the separation distance between Zn and Gd atoms could be well rationalized by the first-principle calculation. Moreover, the fraction of Zn–Gd solute pairs increases first and then decreases due to the precipitation of long-period stacking ordered(LPSO) structures. Both the composition of the structural unit in LPSO structure and the solute enrichment around it are quantified. It is found that Zn and Gd elements are synchronized in the LPSO structure, and solute segregation of pure Zn or Gd is not observed at the transformation front of the LPSO structure in this alloy. In addition, the crystallography of transformation front is further determined by 3DAP data.
文摘A condition for local moment formation in metals derived by Stoddart and March (Ann. Phys. NY 1972 64, 174) is first used to discuss the ferromagnetism of body-centred-cubic Fe. A less detailed discussion is also added on Ni and Co. This leads into a treatment of the non- linear response of such 3d ferromagnets to dilute substitutional impurities. Antiferromagnets responding to local changes in the exchange field caused by such impurities are also studied, Mn in Cr being one such system discussed. The paper concludes with a brief summary of clusters of transition metal atoms, with most attention devoted to Cr and to Mn.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10575046 and 10775062)
文摘The interaction between intense femtosecond laser pulses and hydrogen atomic clusters is studied by a simplified Coulomb explosion model. The dependences of average proton kinetic energy on cluster size, pulse duration, laser intensity and wavelength are studied respectively. The calculated results indicate that the irradiation of a femtosecond laser of longer wavelength on hydrogen atomic clusters may be a simple, economical way to produce highly kinetic hydrogen ions. The phenomenon suggests that the irradiation of femtosecond laser of longer wavelength on deuterium atomic clusters may be easier than that of shorter wavelength to drive nuclear fusion reactions. The product of the laser intensity and the squared laser wavelength needed to make proton energy saturated as a function of the squared cluster radius is also investigated. The proton energy distribution calculated is also shown and compared with the experimental data. Our results are in agreement with the experimental results fairly well.
文摘Ionization potentials and electron affinities of Cux (n = 2-7) atomic clusters with the optimal geom etries have been calculated by use of SC F-Xa-SW method and Slater's transition state theory. Theo retical calcuIations show that the ionization potentiaIs and electron affinities of Cu. (n = 2-7) atom ic clusters have a sharp even / odd alternation with increasing their sizes, which are related to the electronic structure of Cun atomic clusters. The theoretical results are consistent with the related ex perimental ones.
基金financially supported by the National Natural Science Foundation of China(51674060)the Fundamental Research Funds for the Central Universities(DUT18LAB01).
文摘A novel Ni-Cr-Si-B filler metal with the cluster formula of[Cr-Ni12]B2Cr+[B-Ni8Cr]BSi Cr based on the cluster-plus-glue-atom model was designed for vacuum brazing GH4169 alloy.The effect of brazing temperature and brazing time on microstructure and shear strength of GH4169 alloy joints was investigated.The brazed seam was mainly composed ofγ-Ni solid solution.(Nb,Ti)-rich phase and(Cr,Nb,Mo)-rich borides distributed in diffusion zones.The diffusion and aggregation of B,Cr,Nb,and Mo resulted in the variation of phase contrast and morphology of borides.Coarse precipitations in the joint brazed at1240℃consisted of borides,Laves phase andδphase.The shear strength of joints was principally dominated by the brittle precipitations in diffusion zone,and the homogenization of microstructure improved the room-temperature shear strength to 820 MPa with the high-temperature shear strength of 627 MPa for the joint brazed at 1240℃/20 min.The joint fractured in diffusion zone and brazed seam,and the existence of borides and Laves phase in diffusion zone provide the potential origin for crack growth.
基金financially supported by the Projects of Undergraduate Innovation&entrepreneurship Training Plans of Quanzhou Normal University(No.201310399008)Quanzhou‘‘Tong-Jiang Scholar"program,Fujian‘‘MinJiang Scholar"program,program for New Century Excellent Talents in University(No.NCET-13-0879)the Education and Scientific Research Foundation(Class A)for Young Teachers of Education Bureau of Fujian Province,China(No.JA13263)
文摘We exploited a hydrogen-passivated germanium atomic cluster（Ge10H16） as a model to study the mechanism of lithium alloying with germanium. Based on the density functional theory, the electronic and crystal structures of lithium-alloyed Ge10H16 were investigated. The theoretical results indicate that the alloying of lithium with Ge10H16 will weaken the germanium-hydrogen bond and repel the closest germanium atom away from the alloyed lithium atom. Based on the maps of the electron density distribution, the nature of the lithium-germanium chemical bond was analyzed. Moreover, the diffusion process of the lithium on the Ge10H16 cluster was detected, which suggested that there is a close relationship between the diffusion barriers and the coordination number around the lithium atom.
基金Supported patially by the National Nature Science Foundation of China under grant No.10275012
文摘This paper tries to outline the influence of atomic mobility on the initial fabrication of thin films formed by LECBD. Based on our recent studies on low-energy cluster beam deposition (LECBD) by molecular dynamics simulation, two examples, the deposition of small carbon clusters on Si and diamond surfaces and Al clusters on Ni substrate, were mainly discussed. The impact energy of the cluster ranges from 0.1 eV to 100 eV. In the former case, the mobility and the lateral migration of surface atoms, especially the recoil atoms, are enhanced with increasing the impact energy, which promote the film to be smoother and denser. For the latter case, the transverse kinetic energy of cluster atoms, caused mainly by the collision between moving cluster atoms, dominates the lateral spread of cluster atoms on the surface, which is contributive to layer-by-layer growth of thin films. Our result is consistent with the experimental observations that the film structure is strongly dependent on the impact energy. In addition, it elucidates that the atomic mobility takes a leading role in the structure characteristic of films formed by LECBD.
基金supported by the National Natural Science Foundation of China(22305101)the Natural Science Foundation of Jiangsu Province(BK20231032)+1 种基金the Fundamental Research Funds for the Central Universities(JUSRP123020)Startup Funding at Jiangnan University(1045219032220100).
文摘Constructing the desired long-range dual sites to enhance the C–C bond-cleavage and CO-tolerate ability during ethanol oxidation reaction is of importance for further applications.Herein,the concept of holding atomically dispersed NiO_(x)cluster supported on Pt-based high-index facets(NiO_(x)/Pt)is proposed to build O-bridged Pt–Ni dual sites.Strikingly,the obtained NiO_(x)/Pt dual sites show 4.97 times specific activity higher than that of commercial Pt/C(0.35 mA cm^(-2)),as well as outstanding CO-tolerance and durability.The advanced electrochemical in-situ characterizations reveal that the NiO_(x)/Pt can accelerate rapid dehydroxylation and C–C bondcleavage over the Pt–Ni dual sites.Theoretical calculations disclose that the atomically dispersed NiO_(x)species can lower the adsorption/reaction energy barriers of intermediates.This tactic provides a promising methodology on regulating the surface synergistic sites via engineering atomically dispersed oxide site.
文摘Nanometer-sized metal clusters were prepared inside single crystalline MgO films by vacuum co-deposition of metals and MgO. The atomic structure was studied by high-resolution electron microscopy (HREM) and nm-area electron diffraction. The size of the clusters is ranging from 1 nm to 3 nm without those larger than 5 nm, and most of them have definite epitaxial orientations with the MgO matrix films. The character of the composite films is very much useful for the studies of various kinds of physical properties with anisotroPy. The physical properties such as electric transport, magnetic, optical absorption, sintering and catalytic ones were thus measured on the same samples analyzed by HREM by using high sensitivity apparatus with interest of clarifying the retationship between the atomic structure and physical properties
