Metal nanoclusters with well-defined atomic structures offer significant promise in the field of catalysis due to their sub-nanometer size and tunable organic-inorganic hybrid structural features.Herein,we successfull...Metal nanoclusters with well-defined atomic structures offer significant promise in the field of catalysis due to their sub-nanometer size and tunable organic-inorganic hybrid structural features.Herein,we successfully synthesized an 11-core copper(Ⅰ)-alkynyl nanocluster(Cu11),which is stabilized by alkynyl ligands derived from a photosensitive rhodamine dye molecule.Notably,this Cu11cluster exhibited excellent photocatalytic hydrogen evolution activity(8.13 mmol g-1h-1)even in the absence of a mediator and noble metal co-catalyst.Furthermore,when Cu11clusters were loaded onto the surface of TiO_(2)nanosheets,the resultant Cu11@TiO_(2)nanocomposites exhibited a significant enhancement in hydrogen evolution efficiency,which is 60 times higher than that of pure TiO_(2)nanosheets.The incorporation of Cu11clusters within the Cu11@TiO_(2)effectively inhibits the recombination of photogenerated electrons and holes,thereby accelerating the charge separation and migration in the composite material.This work introduces a novel perspective for designing highly active copper cluster-based photocatalysts.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
Platinum-based(Pt)catalysts are notoriously susceptible to deactivation in industrial chemical processes due to carbon monoxide(CO)poisoning.Overcoming this poisoning deactivation of Pt-based catalysts while enhancing...Platinum-based(Pt)catalysts are notoriously susceptible to deactivation in industrial chemical processes due to carbon monoxide(CO)poisoning.Overcoming this poisoning deactivation of Pt-based catalysts while enhancing their catalytic activity,selectivity,and durability remains a major challenge.Herein,we propose a strategy to enhance the CO tolerance of Pt clusters(Pt_n)by introducing neighboring functionalized vip single atoms(such as Fe,Co,Ni,Cu,Sb,and Bi).Among them,antimony(Sb)single atoms(SAs)exhibit significant performance enhancement,achieving 99%CO selectivity and 33.6%CO_(2)conversion at 450℃,Experimental results and density functional theory(DFT)calculations indicate the optimization arises from the electronic interaction between neighboring functionalized Sb SAs and Pt clusters,leading to optimal 5d electron redistribution in Pt clusters compared to other functionalized vip single atoms.The redistribution of 5d electrons weaken both theσdonation andπbackdonation interactions,resulting in a weakened bond strength with CO and enhancing catalyst activity and selectivity.In situ environmental transmission electron microscopy(ETEM)further demonstrates the exception thermal stability of the catalyst,even under H_(2)at 700℃.Notably,the functionalized Sb SAs also improve CO tolerance in various heterogenous catalysts,including Co/CeO_(2),Ni/CeO_(2),Pt/Al_(2)O_(3),and Pt/CeO_(2)-C.This finding provides an effective approach to overcome the primary challenge of CO poisoning in Pt-based catalysts,making their broader applications in various industrial catalysts.展开更多
The experiment explored the Fe_(2)O_(3) reduction process with H_(2)/CO mixed gas and confirmed a promoting effect from CO when its volume proportion in mixed gas is 20% at 850℃.The ReaxFF molecular dynamics(MD)simul...The experiment explored the Fe_(2)O_(3) reduction process with H_(2)/CO mixed gas and confirmed a promoting effect from CO when its volume proportion in mixed gas is 20% at 850℃.The ReaxFF molecular dynamics(MD)simulation method was used to observe the reduction process and provide an atomic-level explanation.The accuracy of the parameters used in the simulation was verified by the density functional theory(DFT)calculation.The simulation shows that the initial reduction rate of H_(2) is much faster than that of CO(from 800 to 950℃).As the reduction proceeds,cementite,obtained after CO participates in the reduction at 850℃,will appear on the iron surface.Due to the active properties of C atoms in cementite,they are easy to further react with the O atoms in Fe_(2)O_(3).The generation of internal CO may destroy the dense structure of the surface layer,thereby affecting the overall reduction swelling of Fe_(2)O_(3).However,excess CO is detrimental to the reaction rate,mainly because of the poor thermodynamic conditions of CO in the temperature range and the molecular diffusion capacity is not as good as that of H_(2).Furthermore,the surface structures obtained after H_(2) and CO reduction have been compared,and it was found that the structure obtained by CO reduction has a larger surface area,thus promoting the sub sequent reaction of H_(2).展开更多
We propose a theoretical framework,based on the two-component Gross-Pitaevskii equation(GPE),for the investigation of vortex solitons(VSs)in hybrid atomic-molecular Bose-Einstein condensates under the action of the st...We propose a theoretical framework,based on the two-component Gross-Pitaevskii equation(GPE),for the investigation of vortex solitons(VSs)in hybrid atomic-molecular Bose-Einstein condensates under the action of the stimulated Raman-induced photoassociation and square-optical-lattice potential.Stationary solutions of the coupled GPE system are obtained by means of the imaginary-time integration,while the temporal dynamics are simulated using the fourth-order Runge-Kutta algorithm.The analysis reveals stable rhombus-shaped VS shapes with topological charges m=1 and 2 of the atomic component.The stability domains and spatial structure of these VSs are governed by three key parameters:the parametric-coupling strength(χ),atomicmolecular interaction strength(g_(12)),and the optical-lattice potential depth(V_(0)).By varyingχand g_(12),we demonstrate a structural transition where four-core rhombus-shaped VSs evolve into eight-core square-shaped modes,highlighting the nontrivial nonlinear dynamics of the system.This work establishes a connection between interactions of cold atoms and topologically structured matter waves in hybrid quantum systems.展开更多
Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient electrocatalysts.Both synergy effect and high atomic utilization of active sites in the composite catalysts result in enh...Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient electrocatalysts.Both synergy effect and high atomic utilization of active sites in the composite catalysts result in enhanced electrocatalytic performance,simultaneously provide a radical analysis of the interrelationship between structure and activity.In this review,the recent advances of single-atomic site catalysts coupled with clusters or nanoparticles are emphasized.Firstly,the synthetic strategies,characterization,dynamics and types of single atoms coupled with clusters/nanoparticles are introduced,and then the key factors controlling the structure of the composite catalysts are discussed.Next,several clean energy catalytic reactions performed over the synergistic composite catalysts are illustrated.Eventually,the encountering challenges and recommendations for the future advancement of synergistic structure in energy-transformation electrocatalysis are outlined.展开更多
Hydrogen storage plays a pivotal role in the hydrogen industry,yet its current status presents a bottle-neck.Diverse strategies have emerged in recent years to address this challenge.MgH_(2) has stood out as a promisi...Hydrogen storage plays a pivotal role in the hydrogen industry,yet its current status presents a bottle-neck.Diverse strategies have emerged in recent years to address this challenge.MgH_(2) has stood out as a promising solid-state hydrogen storage material due to its impressive gravimetric and volumetric hydrogen density,but its practical application is hampered by elevated thermal stability and sluggish kinetics.In this study,we introduce a solution by synthesizing Pd metallene through a one-pot solvothermal method,revealing a distinctive highly curved lamellar structure with a thickness of around 1.6 nm.Incorporating this Pd metallene into MgH_(2) results in a composite system wherein the starting dehydrogenation temperature is significantly lowered to 439 K and complete dehydrogenation occurs at 583 K,releasing 6.14 wt.%hydrogen.The activation energy of dehydrogenation for MgH_(2) was reduced from 170.4 kJ mol^(-1) to 79.85 kJ mol^(-1) after Pd metallene decoration.The enthalpy of dehydrogenation of the MgH_(2)-10 wt.%Pd sample was calculated to be 73 kJ mol^(-1) H_(2)^(-1) and decreased by 4.4 kJ mol^(-1) H_(2)^(-1) from that of dehydrogenation of pure MgH_(2)(77.4 kJ mol^(-1) H_(2)-1).Theoretical calculations show that the average formation energy and average adsorption energy of hydrogen vacancies can be significantly reduced in the presence of both Pd clusters and Pd single atoms on the surface of MgH_(2)/Mg,respectively.It suggests that the synergistic effect of in situ formed Pd single atoms and clusters significantly improves the hydrogenation and dehydrogenation kinetics.The identified active sites in this study hold potential as references for forthcoming multi-sized active site catalysts,underscoring a significant advancement toward resolving hydrogen storage limitations.展开更多
Atomically precise coordination nanoclusters(NCs)constitute a pivotal and rapidly advancing domain in the realms of materials science and chemistry owing to their distinctive crystal structures and exceptional attribu...Atomically precise coordination nanoclusters(NCs)constitute a pivotal and rapidly advancing domain in the realms of materials science and chemistry owing to their distinctive crystal structures and exceptional attributes encompassing molecular magnetism[1],photoluminescence[2],and catalysis[3].Organic ligands play a crucial role in effectively shielding these NCs,serving two primary functions:firstly,vital in preventing NC aggregation,particularly for the formation of robust single-crystal structures;secondly,acting as either bridging or peripheral structural components of NCs[4].This characterization of organic-inorganic hybridization offers unique advantages for unraveling the intricate relationships between structure and properties[5].展开更多
To date,there is still a lack of a comprehensive explanation for caged dynamics which is regarded as one of the intricate dynamic behaviors in amorphous alloys.This study focuses on Pd_(82)Si_(18)as the research objec...To date,there is still a lack of a comprehensive explanation for caged dynamics which is regarded as one of the intricate dynamic behaviors in amorphous alloys.This study focuses on Pd_(82)Si_(18)as the research object to further elucidate the underlying mechanism of caged dynamics from multiple perspectives,including the cage's lifetime,atomic local environment,and atomic potential energy.The results reveal that Si atoms exhibit a pronounced cage effect due to the hindrance of Pd atoms,resulting in an anomalous peak in the non-Gaussian parameters.An in-depth investigation was conducted on the caged dynamics differences between fast and slow Si atoms.In comparison to fast Si atoms,slow Si atoms were surrounded by more Pd atoms and occupied lower potential energy states,resulting in smaller diffusion displacements for the slow Si atoms.Concurrently,slow Si atoms tend to be in the centers of smaller clusters with coordination numbers of 9 and 10.During the isothermal relaxation process,clusters with coordination numbers 9 and 10 have longer lifetimes,suggesting that the escape of slow Si atoms from their cages is more challenging.The findings mentioned above hold significant implications for understanding the caged dynamics.展开更多
This paper examines the interface development between a single crystalline Ag matrix and core-shell AgnCom nanoclusters that have been deposited with energies varying between 0.25 eV and 1.5 eV per atom using computer...This paper examines the interface development between a single crystalline Ag matrix and core-shell AgnCom nanoclusters that have been deposited with energies varying between 0.25 eV and 1.5 eV per atom using computer modeling techniques. Clusters undergo deformation as a result of the slowing down;they may also become epitaxial with the substrate and maintain their core-shell structure. A detailed analysis of the effects of the cluster-surface interaction is conducted over a realistic size and energy range, and a model is created to show how clusters accumulate. It is discovered that both the silver shells and the cobalt cluster cores exhibit limited epitaxy with the substrate, and that the contact produced is only a few atomic layers thick. The effect is higher for Ag shells than for Co cores, and it is not very energy dependent.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
The interactions between AgnO- （n=1-8） and H2 （or D2） were explored by combination of the mass spectroscopy experiments and density function theory （DFT） calculations. The experiments found that all oxygen atoms...The interactions between AgnO- （n=1-8） and H2 （or D2） were explored by combination of the mass spectroscopy experiments and density function theory （DFT） calculations. The experiments found that all oxygen atoms in AgnO- （n--1-8） are inert in the interactions with H2 or D2 at the low temperature of 150 K, which is in contrast to their high reactivity with CO under the same condition. These observations are parallel with the preferential oxidation （PROX） of CO in excess hydrogen catalyzed by dispersed silver species in the condensed phase. Possible reaction paths between AgnO- （n=1-8） and H2 were explored using DFT calculations. The results indicated that adsorption of H2 on any site of AgnO- （n=1-8） is extremely weak, and oxidation of H2 by any kind of oxygen in AgnO- （n=1-8） has an apparent barrier strongly dependent on the adsorption style of the ＂O＂. These experiments and theoretical results about cluster reactions provided molecule-level insights into the activity of atomic oxygen on real silver catalysts.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
The investigation is generalized to clusters with sizes up to 3000 atoms, covering this way the range of sizes experimentally available for low energy cluster beam deposition. The atomic scale modeling is carried on b...The investigation is generalized to clusters with sizes up to 3000 atoms, covering this way the range of sizes experimentally available for low energy cluster beam deposition. The atomic scale modeling is carried on by both Molecular Dynamics and Metropolis Monte Carlo. This represents a huge series of simulations (175 cases) to which further calculations are added by spot when finer tuning of the parameters is necessary. Analyzing the results is a major task which is still in progress. This way, not only a realistic range of sizes is covered, but also the whole range of compositions and the temperature range relevant to the solid and the liquid states.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
Molecular dynamics simulation employing the embedded atom method potential is utilized to investigate nanoscale surface diffusion mechanisms of binary heterogeneous adatoms clusters at 300 K, 500 K, and 700 K. Surface...Molecular dynamics simulation employing the embedded atom method potential is utilized to investigate nanoscale surface diffusion mechanisms of binary heterogeneous adatoms clusters at 300 K, 500 K, and 700 K. Surface diffusion of heterogeneous adatoms clusters can be vital for the binary island growth on the surface and can be useful for the formation of alloy-based thin film surface through atomic exchange process. The results of the diffusion process show that at 300 K, the diffusion of small adatoms clusters shows hopping, sliding, and shear motion; whereas for large adatoms clusters（hexamer and above）, the diffusion is negligible. At 500 K, small adatoms clusters, i.e., dimer, show almost all possible diffusion mechanisms including the atomic exchange process; however no such exchange is observed for adatoms clusters greater than dimer. At 700 K, the exchange mechanism dominates for all types of clusters, where Zr adatoms show maximum tendency and Ag adatoms show minimum or no tendency toward the exchange process. Separation and recombination of one or more adatoms are also observed at 500 K and 700 K. The Ag adatoms also occupy pop-up positions over the adatoms clusters for short intervals. At 700 K, the vacancies are also generated in the vicinity of the adatoms cluster,vacancy formation, filling, and shifting can be observed from the results.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
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
N-doping has significant influence in manipulating the properties of TiO_(2),and this has stimulated the development of N-donor-functionalized titanium-oxo clusters(TOCs)as molecular models to study the structure-prop...N-doping has significant influence in manipulating the properties of TiO_(2),and this has stimulated the development of N-donor-functionalized titanium-oxo clusters(TOCs)as molecular models to study the structure-property relationship.However,the structural type and photoresponsive application are still limited for such TOCs,especially regarding the high-nuclearity TOCs that contain structure unit of TiO_(2)for photocatalysis.Herein,we showed the synthesis of a series of high-nuclearity TOCs 1-3 compounds usingπ-conjugated 1,10-phenanthroline(phen)as chromophore and N-donor functional ligand.Compound 1 features cocrystal structure composed of one[Ti_(26)]~(2+)and half[Ti_(22)]~(2+),which renders it as the first cocrystallized TOC containing two positively charged species and phen-functionalized TOC showing the highest nuclearity up to 37 Ti centers.By adjusting the synthetic conditions,the individual{Ti_(22)}and{Ti_(26)}clusters can also be isolated as Compounds 2 and 3,respectively.The core structure of{Ti_(22)}is mainly constructed from four lacunary{Ti_(4)}derived from pentagonal{Ti(Ti)_5}unit,while{Ti_(26)}is built from four complete{Ti(Ti)_5}unit.Notably,a{Ti_8O_(14)}structure unit of anatase TiO_(2)can be identified in{Ti_(26)}.Based on the unique structural features and proper photophysical and photochemical properties of Compounds 1-3,they are applied for photocatalytic sulfoxidation.Owing to the presence of anatase structure unit in{Ti_(26)}and the synergistic effect from{Ti_(22)}and{Ti_(26)},the catalytic performance presents in the order of Compound 1>Compound 3>Compound 2.This work provides excellent models to understand the structureproperty relationship from the perspective of cocrystallization and Ti-O binding model and will further promote the application of TOCs as functional catalysts for organic transformation.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22371263 and U2004193)Natural Science Foundation of Henan Province(No.232300421225)。
文摘Metal nanoclusters with well-defined atomic structures offer significant promise in the field of catalysis due to their sub-nanometer size and tunable organic-inorganic hybrid structural features.Herein,we successfully synthesized an 11-core copper(Ⅰ)-alkynyl nanocluster(Cu11),which is stabilized by alkynyl ligands derived from a photosensitive rhodamine dye molecule.Notably,this Cu11cluster exhibited excellent photocatalytic hydrogen evolution activity(8.13 mmol g-1h-1)even in the absence of a mediator and noble metal co-catalyst.Furthermore,when Cu11clusters were loaded onto the surface of TiO_(2)nanosheets,the resultant Cu11@TiO_(2)nanocomposites exhibited a significant enhancement in hydrogen evolution efficiency,which is 60 times higher than that of pure TiO_(2)nanosheets.The incorporation of Cu11clusters within the Cu11@TiO_(2)effectively inhibits the recombination of photogenerated electrons and holes,thereby accelerating the charge separation and migration in the composite material.This work introduces a novel perspective for designing highly active copper cluster-based photocatalysts.
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financially supported by the Shanghai RisingStar Program(No.23QA1403700)the National Natural Science Foundation of China(NSFC,Grant No.U2230102)+1 种基金the sponsored by National Key Research and Development Program of China(No.2021YFB3502200)the Shanghai Technical Service Center of Science and Engineering Computing,Shanghai University.
文摘Platinum-based(Pt)catalysts are notoriously susceptible to deactivation in industrial chemical processes due to carbon monoxide(CO)poisoning.Overcoming this poisoning deactivation of Pt-based catalysts while enhancing their catalytic activity,selectivity,and durability remains a major challenge.Herein,we propose a strategy to enhance the CO tolerance of Pt clusters(Pt_n)by introducing neighboring functionalized vip single atoms(such as Fe,Co,Ni,Cu,Sb,and Bi).Among them,antimony(Sb)single atoms(SAs)exhibit significant performance enhancement,achieving 99%CO selectivity and 33.6%CO_(2)conversion at 450℃,Experimental results and density functional theory(DFT)calculations indicate the optimization arises from the electronic interaction between neighboring functionalized Sb SAs and Pt clusters,leading to optimal 5d electron redistribution in Pt clusters compared to other functionalized vip single atoms.The redistribution of 5d electrons weaken both theσdonation andπbackdonation interactions,resulting in a weakened bond strength with CO and enhancing catalyst activity and selectivity.In situ environmental transmission electron microscopy(ETEM)further demonstrates the exception thermal stability of the catalyst,even under H_(2)at 700℃.Notably,the functionalized Sb SAs also improve CO tolerance in various heterogenous catalysts,including Co/CeO_(2),Ni/CeO_(2),Pt/Al_(2)O_(3),and Pt/CeO_(2)-C.This finding provides an effective approach to overcome the primary challenge of CO poisoning in Pt-based catalysts,making their broader applications in various industrial catalysts.
基金financial support from the National Natural Science Foundation of China(Nos.52204335 and 52374319)the National Nature Science Foundation of China(No.52174291)the Central Universities Foundation of China(No.06500170)。
文摘The experiment explored the Fe_(2)O_(3) reduction process with H_(2)/CO mixed gas and confirmed a promoting effect from CO when its volume proportion in mixed gas is 20% at 850℃.The ReaxFF molecular dynamics(MD)simulation method was used to observe the reduction process and provide an atomic-level explanation.The accuracy of the parameters used in the simulation was verified by the density functional theory(DFT)calculation.The simulation shows that the initial reduction rate of H_(2) is much faster than that of CO(from 800 to 950℃).As the reduction proceeds,cementite,obtained after CO participates in the reduction at 850℃,will appear on the iron surface.Due to the active properties of C atoms in cementite,they are easy to further react with the O atoms in Fe_(2)O_(3).The generation of internal CO may destroy the dense structure of the surface layer,thereby affecting the overall reduction swelling of Fe_(2)O_(3).However,excess CO is detrimental to the reaction rate,mainly because of the poor thermodynamic conditions of CO in the temperature range and the molecular diffusion capacity is not as good as that of H_(2).Furthermore,the surface structures obtained after H_(2) and CO reduction have been compared,and it was found that the structure obtained by CO reduction has a larger surface area,thus promoting the sub sequent reaction of H_(2).
基金supported by the National Natural Science Foundation of China(Grant No.62275075)the Natural Science Foundation of Hubei Soliton Research Association(Grant No.2025HBSRA09)+1 种基金joint supported by Hubei Provincial Natural Science Foundation and Xianning of China(Grant Nos.2025AFD401 and 2025AFD405)Israel Science Foundation(Grant No.1695/22).
文摘We propose a theoretical framework,based on the two-component Gross-Pitaevskii equation(GPE),for the investigation of vortex solitons(VSs)in hybrid atomic-molecular Bose-Einstein condensates under the action of the stimulated Raman-induced photoassociation and square-optical-lattice potential.Stationary solutions of the coupled GPE system are obtained by means of the imaginary-time integration,while the temporal dynamics are simulated using the fourth-order Runge-Kutta algorithm.The analysis reveals stable rhombus-shaped VS shapes with topological charges m=1 and 2 of the atomic component.The stability domains and spatial structure of these VSs are governed by three key parameters:the parametric-coupling strength(χ),atomicmolecular interaction strength(g_(12)),and the optical-lattice potential depth(V_(0)).By varyingχand g_(12),we demonstrate a structural transition where four-core rhombus-shaped VSs evolve into eight-core square-shaped modes,highlighting the nontrivial nonlinear dynamics of the system.This work establishes a connection between interactions of cold atoms and topologically structured matter waves in hybrid quantum systems.
基金financially supported by the National Natural Science Foundation of China(22279036)the Innovation Talent Recruitment Base of New Energy Chemistry Device(B21003)the Fundamental Research Funds for the Central Universities(no.2019kfyRCPY100).
文摘Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient electrocatalysts.Both synergy effect and high atomic utilization of active sites in the composite catalysts result in enhanced electrocatalytic performance,simultaneously provide a radical analysis of the interrelationship between structure and activity.In this review,the recent advances of single-atomic site catalysts coupled with clusters or nanoparticles are emphasized.Firstly,the synthetic strategies,characterization,dynamics and types of single atoms coupled with clusters/nanoparticles are introduced,and then the key factors controlling the structure of the composite catalysts are discussed.Next,several clean energy catalytic reactions performed over the synergistic composite catalysts are illustrated.Eventually,the encountering challenges and recommendations for the future advancement of synergistic structure in energy-transformation electrocatalysis are outlined.
基金the National Key R&D Program of China(No.2023YFB4005402)the National Natural Science Foundation of China(Nos.NSFC-NSAF U2330111,52071177)the Natural Science Foundation of Jiangsu province,China(No.BK20221473).
文摘Hydrogen storage plays a pivotal role in the hydrogen industry,yet its current status presents a bottle-neck.Diverse strategies have emerged in recent years to address this challenge.MgH_(2) has stood out as a promising solid-state hydrogen storage material due to its impressive gravimetric and volumetric hydrogen density,but its practical application is hampered by elevated thermal stability and sluggish kinetics.In this study,we introduce a solution by synthesizing Pd metallene through a one-pot solvothermal method,revealing a distinctive highly curved lamellar structure with a thickness of around 1.6 nm.Incorporating this Pd metallene into MgH_(2) results in a composite system wherein the starting dehydrogenation temperature is significantly lowered to 439 K and complete dehydrogenation occurs at 583 K,releasing 6.14 wt.%hydrogen.The activation energy of dehydrogenation for MgH_(2) was reduced from 170.4 kJ mol^(-1) to 79.85 kJ mol^(-1) after Pd metallene decoration.The enthalpy of dehydrogenation of the MgH_(2)-10 wt.%Pd sample was calculated to be 73 kJ mol^(-1) H_(2)^(-1) and decreased by 4.4 kJ mol^(-1) H_(2)^(-1) from that of dehydrogenation of pure MgH_(2)(77.4 kJ mol^(-1) H_(2)-1).Theoretical calculations show that the average formation energy and average adsorption energy of hydrogen vacancies can be significantly reduced in the presence of both Pd clusters and Pd single atoms on the surface of MgH_(2)/Mg,respectively.It suggests that the synergistic effect of in situ formed Pd single atoms and clusters significantly improves the hydrogenation and dehydrogenation kinetics.The identified active sites in this study hold potential as references for forthcoming multi-sized active site catalysts,underscoring a significant advancement toward resolving hydrogen storage limitations.
基金financial support from the National Natural Science Foundation of China(Nos.22171094,21925104,92261204,and 22431005)Hubei Provincial Science and Technology Innovation Team Project[2022]The National Key R&D Program of China(No.2022YFB3807700)。
文摘Atomically precise coordination nanoclusters(NCs)constitute a pivotal and rapidly advancing domain in the realms of materials science and chemistry owing to their distinctive crystal structures and exceptional attributes encompassing molecular magnetism[1],photoluminescence[2],and catalysis[3].Organic ligands play a crucial role in effectively shielding these NCs,serving two primary functions:firstly,vital in preventing NC aggregation,particularly for the formation of robust single-crystal structures;secondly,acting as either bridging or peripheral structural components of NCs[4].This characterization of organic-inorganic hybridization offers unique advantages for unraveling the intricate relationships between structure and properties[5].
基金Project supported by the National Natural Science Foundation of China (Grant No.51701071)the Natural Science Foundation of Hunan Province,China (Grant Nos.2022JJ50115 and 2021JJ30179)the Research Foundation of the Education Bureau of Hunan Province,China (Grant No.22A0522)。
文摘To date,there is still a lack of a comprehensive explanation for caged dynamics which is regarded as one of the intricate dynamic behaviors in amorphous alloys.This study focuses on Pd_(82)Si_(18)as the research object to further elucidate the underlying mechanism of caged dynamics from multiple perspectives,including the cage's lifetime,atomic local environment,and atomic potential energy.The results reveal that Si atoms exhibit a pronounced cage effect due to the hindrance of Pd atoms,resulting in an anomalous peak in the non-Gaussian parameters.An in-depth investigation was conducted on the caged dynamics differences between fast and slow Si atoms.In comparison to fast Si atoms,slow Si atoms were surrounded by more Pd atoms and occupied lower potential energy states,resulting in smaller diffusion displacements for the slow Si atoms.Concurrently,slow Si atoms tend to be in the centers of smaller clusters with coordination numbers of 9 and 10.During the isothermal relaxation process,clusters with coordination numbers 9 and 10 have longer lifetimes,suggesting that the escape of slow Si atoms from their cages is more challenging.The findings mentioned above hold significant implications for understanding the caged dynamics.
文摘This paper examines the interface development between a single crystalline Ag matrix and core-shell AgnCom nanoclusters that have been deposited with energies varying between 0.25 eV and 1.5 eV per atom using computer modeling techniques. Clusters undergo deformation as a result of the slowing down;they may also become epitaxial with the substrate and maintain their core-shell structure. A detailed analysis of the effects of the cluster-surface interaction is conducted over a realistic size and energy range, and a model is created to show how clusters accumulate. It is discovered that both the silver shells and the cobalt cluster cores exhibit limited epitaxy with the substrate, and that the contact produced is only a few atomic layers thick. The effect is higher for Ag shells than for Co cores, and it is not very energy dependent.
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The interactions between AgnO- （n=1-8） and H2 （or D2） were explored by combination of the mass spectroscopy experiments and density function theory （DFT） calculations. The experiments found that all oxygen atoms in AgnO- （n--1-8） are inert in the interactions with H2 or D2 at the low temperature of 150 K, which is in contrast to their high reactivity with CO under the same condition. These observations are parallel with the preferential oxidation （PROX） of CO in excess hydrogen catalyzed by dispersed silver species in the condensed phase. Possible reaction paths between AgnO- （n=1-8） and H2 were explored using DFT calculations. The results indicated that adsorption of H2 on any site of AgnO- （n=1-8） is extremely weak, and oxidation of H2 by any kind of oxygen in AgnO- （n=1-8） has an apparent barrier strongly dependent on the adsorption style of the ＂O＂. These experiments and theoretical results about cluster reactions provided molecule-level insights into the activity of atomic oxygen on real silver catalysts.
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The investigation is generalized to clusters with sizes up to 3000 atoms, covering this way the range of sizes experimentally available for low energy cluster beam deposition. The atomic scale modeling is carried on by both Molecular Dynamics and Metropolis Monte Carlo. This represents a huge series of simulations (175 cases) to which further calculations are added by spot when finer tuning of the parameters is necessary. Analyzing the results is a major task which is still in progress. This way, not only a realistic range of sizes is covered, but also the whole range of compositions and the temperature range relevant to the solid and the liquid states.
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.
文摘Molecular dynamics simulation employing the embedded atom method potential is utilized to investigate nanoscale surface diffusion mechanisms of binary heterogeneous adatoms clusters at 300 K, 500 K, and 700 K. Surface diffusion of heterogeneous adatoms clusters can be vital for the binary island growth on the surface and can be useful for the formation of alloy-based thin film surface through atomic exchange process. The results of the diffusion process show that at 300 K, the diffusion of small adatoms clusters shows hopping, sliding, and shear motion; whereas for large adatoms clusters（hexamer and above）, the diffusion is negligible. At 500 K, small adatoms clusters, i.e., dimer, show almost all possible diffusion mechanisms including the atomic exchange process; however no such exchange is observed for adatoms clusters greater than dimer. At 700 K, the exchange mechanism dominates for all types of clusters, where Zr adatoms show maximum tendency and Ag adatoms show minimum or no tendency toward the exchange process. Separation and recombination of one or more adatoms are also observed at 500 K and 700 K. The Ag adatoms also occupy pop-up positions over the adatoms clusters for short intervals. At 700 K, the vacancies are also generated in the vicinity of the adatoms cluster,vacancy formation, filling, and shifting can be observed from the results.
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
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financially supported by the National Natural Science Foundation of China(Nos.21901037,21901038 and 92161111)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning+1 种基金the Fundamental Research Funds for the Central Universities(No.2232019G-07)the International Cooperation Fund of Science and Technology Commission of Shanghai Municipality(No.21130750100)。
文摘N-doping has significant influence in manipulating the properties of TiO_(2),and this has stimulated the development of N-donor-functionalized titanium-oxo clusters(TOCs)as molecular models to study the structure-property relationship.However,the structural type and photoresponsive application are still limited for such TOCs,especially regarding the high-nuclearity TOCs that contain structure unit of TiO_(2)for photocatalysis.Herein,we showed the synthesis of a series of high-nuclearity TOCs 1-3 compounds usingπ-conjugated 1,10-phenanthroline(phen)as chromophore and N-donor functional ligand.Compound 1 features cocrystal structure composed of one[Ti_(26)]~(2+)and half[Ti_(22)]~(2+),which renders it as the first cocrystallized TOC containing two positively charged species and phen-functionalized TOC showing the highest nuclearity up to 37 Ti centers.By adjusting the synthetic conditions,the individual{Ti_(22)}and{Ti_(26)}clusters can also be isolated as Compounds 2 and 3,respectively.The core structure of{Ti_(22)}is mainly constructed from four lacunary{Ti_(4)}derived from pentagonal{Ti(Ti)_5}unit,while{Ti_(26)}is built from four complete{Ti(Ti)_5}unit.Notably,a{Ti_8O_(14)}structure unit of anatase TiO_(2)can be identified in{Ti_(26)}.Based on the unique structural features and proper photophysical and photochemical properties of Compounds 1-3,they are applied for photocatalytic sulfoxidation.Owing to the presence of anatase structure unit in{Ti_(26)}and the synergistic effect from{Ti_(22)}and{Ti_(26)},the catalytic performance presents in the order of Compound 1>Compound 3>Compound 2.This work provides excellent models to understand the structureproperty relationship from the perspective of cocrystallization and Ti-O binding model and will further promote the application of TOCs as functional catalysts for organic transformation.
