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Geometric edge effect on the interface of Au/CeO_(2)nanocatalysts for CO oxidation

Nano Research 2024年第6期17卷 4986-4993页

作者： Hongpeng LiuZhongliang Cao Siyuan Yang Qingye Ren Zejian Dong Wei Liu Zi-An Li Xing Chen Langli Luo Institute of Molecular Plus Tianjin UniversityTianjin 300072China Dalian National laboratory for clean energy Dalian Institute of Chemical Physics(DICP)Chinese Academy of SciencesDalian 116023China State Key laboratory of Featured Metal Materials and Life-cycle Safety for Composite structures and School of Physical Science and TechnologyGuangxi UniversityNanning 530004China Haihe laboratory of Sustainable Chemical Transformations Tianjin 300192China

The oxide supports play a crucial role in anchoring and promoting the active metal species by geometric confinement and chemical *** design and synthesis of the well-defined oxide support with specific morphology such as size,shape,and exposed facets have attracted extensive research efforts,which directly reflects on their catalytic *** this study,using an Au/CeO_(2)-nanorod model catalyst,we demonstrate an edge effect on the Au/CeO_(2)interfacial structure,which shows a prominent effect on the structure-performance relationship in the CO oxidation *** specific“edge-interface”structure features an“edge-on”Au nanoparticles position on rod-shaped CeO_(2)support,confirmed by atomic-scale electron microscopy characterization,which introduces additional degrees of freedom in coordination environment,chemical state,bond length,and *** with theocratical calculations and in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)investigations,we confirmed that this“edge-interface”has distinct adsorption properties due to the change of O vacancy formation energy as well as the chemical states of Au resulting from the electron transfer and redistribution between the metal and the *** results demonstrate a non-conventional geometric effect of rod-shaped supported metal catalysts on the catalytic performance,which could provide insights into the atomic-precise utilization of catalysts.

关键词： ceria nanorod supported catalyst edge-effect atomic scale

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The Edge Magnetization and Strip Phase of Graphene quantum Dots with Long-Range Coulomb Interaction

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Chinese Physics Letters 2014年第4期31卷 150-154页

作者： LINing ZHU Wen-Huan LIANG Qi DING Guo-Hui Instrumental Analysis Center Shanghai Jiao Tong University Shanghai 200240 Key laboratory of Artificial structures and quantum Control (Ministry of Bducation) Department of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240

We investigate the magnetism and optical absorption properties of charge neutral hexagonal graphene quantum dots （GODs） terminated with zigzag edges by using a tight-binding Hubbard type model for the 7r electrons. Within the Hartree Fock approximation and taking into account the long-range Coulomb interaction, our cal- culation yields a ferromagnetic ground state with magnetic moments localized on the edges for GODs, and also gives an antiferromagnetism state with the energy very c/ose to the ferromagnetism ground state. We find that both the ferromagnetic and the antiferrornagnetic states have stripe patterned charge density distributions as a result of the long-range Coulomb interaction. The optical conductivity for GQDs has an energy gap in the low frequency regime in contrast to the bulk neutral graphene sheet where a universal constant is approached.

关键词： Interaction The Edge Magnetization magnetism

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High dimensional AdS-like black hole and phase transition in Einstein-bumblebee gravity

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Chinese Physics C 2023年第4期47卷 236-246页

作者：丁持坤石雨陈骏周跃兵刘长青 Department of Physics Huaihua UniversityHuaihuaHunan 418008China Department of Physics Hunan University of HumanitiesScience and TechnologyLoudiHunan 417000China Key laboratory of Low Dimensional quantum structures and quantum Control of Ministry of Education and Synergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal UniversityChangsha 410081China

In this study,we obtained an exact high dimensional anti-de Sitter(AdS)black hole solution in Einsteinbumblebee gravity *** AdS-like black hole can only exist with a linear functional potential of the bumblebee *** found that the Smarr formula and the first law of black hole thermodynamics can still be constructed in this Lorentz symmetry breaking black hole spacetime,but the conceptions of the black hole horizon area/entropy and the volume inside the horizon should be renewed due to its *** also found that two types of phase transition exist:small-large black hole phase transition and Hawking-Page phase transition,like those of the Schwarzschild AdS black *** Lorentz symmetry breaking,the black hole mass at the divergent point of heat capacity becomes small,and the Gibbs free energy of the meta-stable large black hole is also smaller,showing that the large stable black hole can be more easily formed.

关键词： bumblebee field black hole solution first law phase transition

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Surface evolution of thermoelectric material KCu_(4)Se_(3) explored by scanning tunneling microscopy

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Chinese Physics B 2024年第8期33卷 422-427页

作者：夏玉敏马妮蔡德胜刘宇舟谷易通于淦霍思宇庞文慧肖翀秦胜勇 International Center for quantum Design of Functional Materials(ICQD) Hefei National Laboratory for Physical Sciences at Microscale(HFNL)University of Science and Technology of ChinaHefei 230026China CAS Key laboratory of Strong Coupled quantum Matter Physics Department of PhysicsUniversity of Science and Technology of ChinaHefei 230026China Hefei National laboratory for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China Institute of energy Hefei Comprehensive National Science CenterHefei 230031China Dalian National laboratory for clean energy Chinese Academy of Sciences(CAS)Dalian 116023China Hefei National laboratory University of Science and Technology of ChinaHefei 230088China

Novel two-dimensional thermoelectric materials have attracted significant attention in the field of thermoelectric due to their low lattice thermal conductivity.A comprehensive understanding of their microscopic structures is crucial for driving further the optimization of materials properties and developing novel functional ***,by using in situ scanning tunneling microscopy,we report the atomic layer evolution and surface reconstruction on the cleaved thermoelectric material KCu_(4)Se_(3) for the first *** clearly revealed each atomic layer,including the naturally cleaved K atomic layer,the intermediate Se^(2-)atomic layer,and the Se^(-)atomic layer that emerges in the thermodynamic-stable *** from the maj ority of studies that predominantly concentrate on macroscopic measurements of the charge transport,our results reveal the coexistence of potassium disorder and complex reconstructed patterns of selenium,which potentially influences charge carrier and lattice *** results provide direct insight into the surface microstructures and evolution of KCu_(4)Se_(3),and shed useful light on designing functional materials with superior performance.

关键词： thermoelectric KCu_(4)Se_(3) scanning tunneling microscopy(STM) evolution

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Nanoscale Impact Ionization and Electroluminescence in a Biased Scanning-Tunneling-Microscope Junction

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Chinese Physics Letters 2022年第3期39卷 99-104页

作者： Lehua Gu Shuang Wu Shuai Zhang Shiwei Wu State Key laboratory of Surface Physics Key Laboratory of Micro and Nano Photonic Structures(MOE)and Department of PhysicsFudan UniversityShanghai 200433China Shanghai Qi Zhi Institute Shanghai 200232China Institute for Nanoelectronic Devices and quantum Computing Fudan UniversityShanghai 200433China Shanghai Research Center for quantum Sciences Shanghai 201315China

Electroluminescence from a p-type Ga As(110)surface was induced by tunneling electrons in a scanning tunneling microscope under both polarities of bias *** optical spectra exhibit a polarity-independent luminescence peak at 1.47 eV resulting from the exciton ***,the quantum yield of photon emission at negative bias voltage is two orders of magnitude weaker than that at positive bias ***,the luminescence at negative bias voltage shows the linear dependence of bias voltage,distinct from the rapid rise due to resonant electron injection at positive ***,the threshold bias voltage for electroluminescence at negative bias is nearly twice the bandgap of Ga As,not simply satisfying the energy conservation for the creation of an electron–hole *** theoretical calculation,we propose an impact ionization model to nicely explain the newly observed electroluminescence at negative bias *** believe that this mechanism of impact ionization could be readily applied to other nanoscale optoelectronics including 2D semiconductors and 1D nanostructures.

关键词： tunneling luminescence Tunnel

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Theoretical insights into strong intrinsic piezoelectricity of blue-phosphorus-like group-IV monochalcogenides

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Nano Research 2022年第1期15卷 209-216页

作者： Yuxin Dai Xiaoli Zhang Yu Cui Mengyuan Li Yao Luo Fan Jiang Renqiang Zhao Yucheng Huang College of Chemistry and Material Science Key Laboratory of Electrochemical Clean Energy of Anhui Higher Education InstitutesThe Key Laboratory of Functional Molecular SolidsMinistry of EducationAnhui Laboratory of Molecule-Based MaterialsAnhui Normal UniversityWuhu 241000China

On the basis of known structures of 13-GeTe bulk and the derived monolayer,we proposed a series of structural analogues MXs(M=Ge,Sn;X=S,Se,Te)with an intrinsic built-in electric field via a substitution *** first-principles calculations,we demonstrated that these MX monolayers and bulks are thermodynamically,dynamically and mechanically stable,and the stabilities of bulks are more robust than the monolayer *** calculations showed that the monolayers have large band gaps ranging from 2.38 to 3.27 eV while the bulks have pronounced small band gaps ranging from 0.06 to 0.78 *** calculated piezoelectric coefficients d11 for the MX monolayers are in the range from 6.6 to 10.9 ***,the calculated d33 for the MX bulks are as high as 40.3-213.7 pm/*** correlating atomic polarizability,atomic mass,relative ion motion,Bader charge and lattice parameters,we proposed an empirical model to estimate the piezoelectric coefficients for the two-dimensional:(2D)MXs,where a nice match between the estimated ones and the calculated ones was *** versatile electronic propertiesand large piezoelectric coefficients endow MXs a broad prospect of application in optoelectronic and piezoelectric devices,and the revealed underlying mechanisms offer valuable guidelines for seeking novel piezoelectrics.

关键词： piezoelectricity Janus density functional theory electronic property blue-phosphorus group-IV monochalcogenides

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Effect of drum structure on particle mixing behavior based on DEM method

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Particuology 2023年第3期74卷 74-91页

作者： Ganggang Xu Yong Zhang Xigang Yang Guoqing Chen Baosheng Jin Key laboratory of energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing210096China State Key laboratory of clean and Efficient Coal-fired Power Generation and Pollution Control China Energy Science and Technology Research Institute Co.Ltd.Nanjing210023China

The optimization of the drum structure is beneficial to improve the particle motion and mixing in rotary *** this work,two kinds of drum structures,Lacy cylinder drum(LC)and Lacy-lifters cylinder drum(LLC),are developed on the basic of cylinder drum to enhance the heat transfer *** particle motion and mixing process are simulated by DEM *** on the grid independence and model validation,the contact number between particles and wall,particle velocity profile,thickness of active layer,particle exchange coefficient,particle concentration profile and mixing index are *** influences of the drum structure and the operation parameters are further *** results show that the contact number between particles and wall is improved in LC and LLC compared to cylinder *** particle velocity in LC is higher than that in cylinder drum at high rotating speed,and the particle velocity of the particle falling region is significantly improved in *** to cylinder drum and LC,the thickness of active layer in LLC is smaller,while the local particle mixing quality is proved to be the best in the active *** addition,the particle exchange coefficients between static region and active region in the three drums are compared and LLC is found tending to weaken the particle ***,the fluctuations of particle concentration in the active region,static region,and boundary region are weakened in LLC,and the equilibrium state is reached *** addition,the overall particle mixing performance in cylinder drum,LC and LLC is *** particle mixing performance in cylinder drum is the worst,while the difference in mixing quality of LC and LLC depends on the operation conditions.

关键词： Rotating drum Drum structure Particle velocity profile Thickness of active layer Particle mixing

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Magnetic Interactions and Band Gaps of the(CrO_(2))_(2)/(MgH_(2))_(n) Superlattices

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Chinese Physics Letters 2022年第11期39卷 57-62页

作者： Wanfei Shan Jiangtao Du Weidong Luo Key laboratory of Artificial structures and quantum Control(Ministry of Education) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Institute of Natural Sciences Shanghai Jiao Tong UniversityShanghai 200240China

Lattice superlattices constructed with different materials such as ferromagnets and insulators at atomic scale provide an ideal platform for exploring many emergent physical *** the present work,a new type of superlattices composed of ferromagnetic half-metal CrO_(2),with a thickness of two atomic layers,together with insulating MgH_(2) are *** theoretical studies on the(CrO_(2))_(2)/(MgH_(2))_(n) (n=2,3,4,5,6)superlattices are carried out based on first-principles density-functional theory *** superlattices are ferromagnetic semiconductors with similar intra-layer magnetic exchange couplings between Cr *** the thickness of the MgH_(2) layer increases,the magnetic exchange interaction between inter-layer Cr ions shows oscillating decaying behavior,while the energy band gaps show a small *** understanding of magnetic couplings in these superlattices provides a pathway for constructing new ferromagnetic semiconductors.

关键词： ferromagnetic coupling layer

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Strong decays of the low-lying bottom strange baryons

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Science China(Physics,Mechanics & Astronomy) 2021年第6期64卷 51-57页

作者： Hui-Zhen He Wei Liang Qi-Fang Lü Yu-Bing Dong Department of Physics Hunan Normal UniversityChangsha 410081China Synergetic Innovation Center for quantum Effects and Applications(SICQEA) Changsha 410081China Key laboratory of Low-Dimensional quantum structures and quantum Control of Ministry of Education Changsha 410081China Institute of High energy Physics Chinese Academy of SciencesBeijing 100049China Theoretical Physics Center for Science Facilities(TPCSF) Chinese Academy of SciencesBeijing 100049China School of Physical Sciences University of Chinese Academy of SciencesBeijing 101408China

In this work,the strong decay behaviors of theλ-mode low-lyingΞ_(b) andΞ^(’)_(b) baryons are investigated within the 3 P0 *** results suggest that all of the low-lying 3F statesΞ_(b)(2 S),Ξ_(b)(1 P),andΞ_(b)(1 D)have small decay widths of less than 20 MeV,and these states have good potentials to be observed in theΞ^(’)_(b)πandΞ^(’)_(b)^(*)πinvariant ***,most of the 6F multiplets are relatively narrow and may decay into theΞ_(b)π,Ξ^(’)_(b)π,Ξ^(’)_(b)^(^(*))π,andΔbK final *** the masses and strong decay behaviors,we can assign the newly observedΞ_(b)(6100)resonance as theΞ_(b)(1 P)state with J^(P)=3/2-and interpret theΞ_(b)(6227)structure as the J^(P)=3/2-Ξ^(’)_(b)(1 P)state with a proper mixing *** expect that our predictions for these excited bottom strange baryons will provide helpful information for future experimental research.

关键词： bottom strange baryons strong decays ^(3)P0 model

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Preparation and characterization of vanadium(IV) oxide supported on SBA-15 and its catalytic performance in benzene hydroxylation to phenol using molecular oxygen

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Journal of Natural Gas Chemistry 2012年第5期21卷 481-487页

作者： Xing Chen Wenguang Zhao Feng Wang Jie Xu Dalian National laboratory for clean energy State Key Laboratory of CatalysisDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina Graduate University of Chinese Academy of Sciences Beijing 100049China

Preparation of dispersed transition metal oxides catalyst with low oxidation state still remains a challenging task in heterogeneous *** this study,vanadium oxides supported on zeolite SBA-15 have been prepared under hydrothermal condition using V 2 O 5 and oxalic acid as sources of vanadium and reductant,*** structures of samples,especially the oxidation state of vanadium,and the surface distribution of vanadium oxide species,have been thoroughly characterized using various techniques,including N 2-physisorption,X-ray diffraction（XRD）,transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）,UV-visible spectra（UV-Vis） and UV-visible-near infrared spectra（UV-Vis-NIR）.It is found that the majority of supported vanadium was in the form of vanadium（IV） oxide species with the low valence of *** adjusting hydrothermal treatment time,the surface distribution of vanadium（IV） oxide species can be tuned from vanadium（IV） oxide cluster to *** materials have been tested in the hydroxylation of benzene to phenol in liquid-phase with molecular oxygen in the absence of *** catalyst exhibits high selectivity for phenol（61%） at benzene conversion of 4.6%,which is a relatively good result in comparison with other studies employing molecular oxygen as the oxidant.

关键词： benzene phenol selective oxidation vanadium SBA-15 molecular oxygen

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