Time filter

Source Type

Huang L.,CAS Institute of Physics | Huang L.,Science and Technology on Surface Physics and Chemistry Laboratory | Du L.,CAS Institute of Physics | Dai X.,CAS Institute of Physics
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

Motivated by the unexplored complexity of the phase diagrams for multiorbital Hubbard models, a three-band Hubbard model at integer fillings (N=4) with orbital degeneracy lifted partially by crystal field splitting is analyzed systematically in this work. By using the single-site dynamical mean-field theory and rotationally invariant Gutzwiller approximation, we have computed the full phase diagram with Coulomb interaction strength U and crystal field splitting Δ. We find a large region in the phase diagram where an orbital-selective Mott phase will be stabilized by the positive crystal field lifting the orbital degeneracy. Further analysis indicates that Hund's rule coupling is essential for the orbital-selective Mott phase, and the transition toward this phase is accompanied by a high-spin to low-spin transition. Such a model may be relevant for the recently discovered Ru-based materials. © 2012 American Physical Society.


Huang L.,CAS Institute of Physics | Huang L.,Science and Technology on Surface Physics and Chemistry Laboratory | Wang Y.,CAS Institute of Physics | Dai X.,CAS Institute of Physics
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

The metal-insulator and spin state transitions of CoO under high pressure are studied by using density functional theory combined with dynamical mean-field theory. Our calculations predict that the metal-insulator transition in CoO is a typical orbital selective insulator-to-metal transition, where the t 2g orbitals of a Co 3d shell become metallic first around 60 GPa while the e g orbitals still remain insulating until 170 GPa. Further studies of the spin states of a Co 3d shell reveal that the orbital selective Mott phase in the intermediate pressure regime is mainly stabilized by the high-spin state of the Co 3d shell, and the transition from this phase to the fully metallic state is driven mainly by the high-spin to low-spin transition of the Co2 + ions. Our results are in good agreement with the most recent transport and x-ray emission experiments under high pressure. © 2012 American Physical Society.


Zhu X.-G.,University of Aarhus | Zhu X.-G.,Science and Technology on Surface Physics and Chemistry Laboratory | Hofmann P.,University of Aarhus
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

Topological insulators support metallic surface states whose existence is protected by the bulk band structure. It was predicted early that the topology of the surface-state Fermi contour should depend on several factors, such as the surface orientation and termination, and this raises the question to what degree a given surface state is protected by the bulk electronic structure upon structural changes. Using tight-binding calculations, we explore this question for the prototypical topological insulator Bi1-xSbx, studying different terminations of the (111) and (110) surfaces. We also consider the implications of the topological protection for (110) surfaces for the semimetals Bi and Sb. © 2014 American Physical Society.


Zhao P.,University of Bordeaux 1 | Zhao P.,Science and Technology on Surface Physics and Chemistry Laboratory | Li N.,University of Bordeaux 1 | Salmon L.,French National Center for Scientific Research | And 3 more authors.
Chemical Communications | Year: 2013

"Click" chemistry now offers access to a great variety of triazoles, and the first example of a strategy to stabilize gold nanoparticles (AuNPs) with a new 1,2,3-triazole-mPEG ligand is developed here together with preliminary examples of possible applications. © 2013 The Royal Society of Chemistry.


Huang D.,Science and Technology on Surface Physics and Chemistry Laboratory | Zhao P.,Science and Technology on Surface Physics and Chemistry Laboratory | Astruc D.,University of Bordeaux 1
Coordination Chemistry Reviews | Year: 2014

A short overview of the multiple coordination modes of 1,2,3-triazole- and related transition-metal complexes are provided, then the implication of and catalysis with transition-metal-1,2,3-triazole complexes are detailed with Mn, Fe, Ni, Cu, Ru, Rh, Ir, Pd, and Au catalysts including various ligand coordination modes and mechanistic features. © 2014 Elsevier B.V.


Zhao P.,Science and Technology on Surface Physics and Chemistry Laboratory | Feng X.,Science and Technology on Surface Physics and Chemistry Laboratory | Huang D.,Science and Technology on Surface Physics and Chemistry Laboratory | Yang G.,Science and Technology on Surface Physics and Chemistry Laboratory | And 2 more authors.
Coordination Chemistry Reviews | Year: 2015

This review presents the basic concepts and recent developments and advances of gold nanoparticle (AuNP)-catalyzed 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP) by sodium borohydride, including the catalytic mechanism, the variety of stabilizers, and dendritic, natural and heterogeneous AuNP supports. The nano-gold catalysts are classified according to different stabilizers, the review contains 205 citations. © 2015.


Xiong R.,Science and Technology on Surface Physics and Chemistry Laboratory | Sang G.,Science and Technology on Surface Physics and Chemistry Laboratory | Yan X.,Science and Technology on Surface Physics and Chemistry Laboratory | Zhang G.,Science and Technology on Surface Physics and Chemistry Laboratory | And 2 more authors.
Chemical Communications | Year: 2013

The catalytic mechanism of doped complex hydrides for hydrogen storage remains unconfirmed. Here, we report a simple method to separate the active species of Ti-based catalysts in NaAlH4 by filtration using tetrahydrofuran (THF) as solvent. The results show that the average particle size of the obtained Al-Ti active species is 30-50 nm. © The Royal Society of Chemistry 2013.


Xiong R.,Science and Technology on Surface Physics and Chemistry Laboratory | Sang G.,Science and Technology on Surface Physics and Chemistry Laboratory | Yan X.,Science and Technology on Surface Physics and Chemistry Laboratory | Zhang G.,Science and Technology on Surface Physics and Chemistry Laboratory | Ye X.,Science and Technology on Surface Physics and Chemistry Laboratory
Journal of Materials Chemistry | Year: 2012

Combination of nanoconfinement and catalyst addition is a promising strategy to enhance the kinetics and reversibility of hydrogen storage in complex hydrides. Herein, Ti-loaded high-ordered mesoporous carbons (Ti-OMCs) were directly synthesized via a solvent evaporation induced self-assembly method (EISA) with in situ crystallization and carbonation technology using phenolic resols, tetrabutyl titanate (Ti(OBu) 4) and triblock copolymer F127 as organic carbon sources, Ti sources and templates, respectively. The obtained Ti-OMCs exhibit uniform pore sizes (4 nm), high specific surface area (427.9 m 2 g -1) and large pore volumes (0.34 cm 3 g -1), which were used to combine catalyst addition and nanoconfinement to improve the hydrogen storage properties of NaAlH 4 by melt infiltration. The hydrogen desorption curves show that NaAlH 4 with Ti-OMCs exhibits better kinetic properties than both nanocrystalline TiO 2 catalysed NaAlH 4 and melt-infiltrated NaAlH 4 with high ordered mesoporous carbons (OMCs). The hydrogen-release onset temperature of NaAlH 4 with Ti-OMCs is reduced to less than 60 °C, and 80% hydrogen is released in less than 20 min. In addition, NaAlH 4 with Ti-OMCs exhibit good reversibility and cycling stability, and the optimum rehydrogention temperature is 120 °C. © The Royal Society of Chemistry 2012.


Lu H.Y.,Science and Technology on Surface Physics and Chemistry Laboratory
Materials Science Forum | Year: 2015

In this paper, we study the ground-state and lattice dynamical properties of β-UH--3 by means of the first-principles density functional theory within the local spin-density approximation (LSDA)+U formulism. The lattice constants and electronic structure are correctly described by taking into account the strong on-site Coulomb repulsion among the 5f electrons localized on uranium atoms. Good agreement with experiments is achieved by tuning the effective Hubbard parameter at around 4 eV. The phonon band structure confirms the dynamical stability of β-UH--3, and the Raman-active modes are consistent with Raman spectrum measurements. The substitution of the deuterium (tritium) atom for hydrogen atom makes significant variations in the typical frequency of Raman-active modes. It is found that the Raman-active mode frequency is approximately inversely proportional to the square root of the hydrogen isotope mass. We conclude that Raman spectrum provides a powerful method for detecting hydrogen isotopic effects. © (2015) Trans Tech Publications, Switzerland.


Li N.,CNRS Institute of Molecular Sciences | Zhao P.,CNRS Institute of Molecular Sciences | Zhao P.,Science and Technology on Surface Physics and Chemistry Laboratory | Astruc D.,CNRS Institute of Molecular Sciences
Angewandte Chemie - International Edition | Year: 2014

Anisotropic gold nanoparticles (AuNPs) have attracted the interest of scientists for over a century, but research in this field has considerably accelerated since 2000 with the synthesis of numerous 1D, 2D, and 3D shapes as well as hollow AuNP structures. The anisotropy of these nonspherical, hollow, and nanoshell AuNP structures is the source of the plasmon absorption in the visible region as well as in the near-infrared (NIR) region. This NIR absorption is especially sensitive to the AuNP shape and medium and can be shifted towards the part of the NIR region in which living tissue shows minimum absorption. This has led to crucial applications in medical diagnostics and therapy ("theranostics"), especially with Au nanoshells, nanorods, hollow nanospheres, and nanocubes. In addition, Au nanowires (AuNWs) can be synthesized with longitudinal dimensions of several tens of micrometers and can serve as plasmon waveguides for sophisticated optical devices. The application of anisotropic AuNPs has rapidly spread to optical, biomedical, and catalytic areas. In this Review, a brief historical survey is given, followed by a summary of the synthetic modes, variety of shapes, applications, and toxicity issues of this fast-growing class of nanomaterials. Function follows form: Anisotropic gold nanoparticles (AuNPs) have attracted the interest of scientists for over a century. Research in this field has considerably accelerated since 2000 with the synthesis of numerous 1D, 2D, and 3D shapes as well as hollow AuNP structures. The synthetic modes, variety of shapes, applications, and toxicity issues of this fast-growing class of nanomaterials are reviewed here. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Loading Science and Technology on Surface Physics and Chemistry Laboratory collaborators
Loading Science and Technology on Surface Physics and Chemistry Laboratory collaborators