Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry

Xiamen Fujian, China

Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry

Xiamen Fujian, China
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Sun D.,Fuzhou University | Liu W.,Fuzhou University | Fu Y.,Fuzhou University | Fu Y.,Zhejiang Normal University | And 6 more authors.
Chemistry - A European Journal | Year: 2014

M-doped NH2-MIL-125(Ti) (M=Pt and Au) were prepared by using the wetness impregnation method followed by a treatment with H2 flow. The resultant samples were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS) analyses, N2-sorption BET surface area, and UV/Vis diffuse reflectance spectroscopy (DRS). The photocatalytic reaction carried out in saturated CO2 with triethanolamine (TEOA) as sacrificial agent under visible-light irradiations showed that the noble metal-doping on NH 2-MIL-125(Ti) promoted the photocatalytic hydrogen evolution. Unlike that over pure NH2-MIL-125(Ti), in which only formate was produced, both hydrogen and formate were formed over Pt- and Au-loaded NH 2-MIL-125(Ti). However, Pt and Au have different effects on the photocatalytic performance for formate production. Compared with pure NH 2-MIL-125(Ti), Pt/NH2-MIL-125(Ti) showed an enhanced activity for photocatalytic formate formation, whereas Au has a negative effect on this reaction. To elucidate the origin of the different photocatalytic performance, electron spin resonance (ESR) analyses and density functional theory (DFT) calculations were carried out over M/NH2-MIL-125(Ti).The photocatalytic mechanisms over M/NH2-MIL-125(Ti) (M=Pt and Au) were proposed. For the first time, the hydrogen spillover from the noble metal Pt to the framework of NH2-MIL-125(Ti) and its promoting effect on the photocatalytic CO2 reduction is revealed. The elucidation of the mechanism on the photocatalysis over M/NH2-MIL-125(Ti) can provide some guidance in the development of new photocatalysts based on MOF materials. This study also demonstrates the potential of using noble metal-doped MOFs in photocatalytic reactions involving hydrogen as a reactant, like hydrogenation reactions. Noble performance: The loading of noble metals can promote the photocatalytic hydrogen evolution over NH2-MIL-125(Ti), but Pt and Au have different effects on its photocatalytic formate production (see figure). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zhang P.,Xiamen University | Hu C.H.,Xiamen University | Wu S.Q.,Xiamen University | Zhu Z.Z.,Xiamen University | And 2 more authors.
Physical Chemistry Chemical Physics | Year: 2012

Structural properties, thermodynamic stability and delithiation process for Li 2FeSiO 4 polymorphs are investigated by using density functional theory (DFT) within the DFT + U framework. Three Li 2FeSiO 4 polymorphs crystallizing in space group Pmn2 1, P2 1/n, and Pmnb have been considered. The investigations demonstrate that the strong Si-O bonds remain almost unchanged during the lithiation-delithiation process for all the polymorphs, which contribute significantly to the structural stability. On the other hand, the differences in local environment around FeO 4 tetrahedra will be translated into varying degrees of distortion, which shows a significant influence on the structural stability and average voltages. The average voltages obtained here are in good agreement with the experimental values. Furthermore, the possibility of extracting more than one lithium ions per formula unit from Li 2FeSiO 4 of P2 1/n is also discussed. © 2012 the Owner Societies.

Hu C.-H.,Xiamen University | Zhang P.,Xiamen University | Liu H.-Y.,Jimei University | Wu S.-Q.,Xiamen University | And 3 more authors.
Journal of Physical Chemistry C | Year: 2013

As a first step toward gaining a microscopic understanding of the fluorination of bilayer graphene (BLG) as the electrode material for lithium-ion batteries, the structural stability and electronic and magnetic properties of fluorinated BLG have been investigated using density functional theory. For the fully fluorinated BLG (C1F), the chair configuration is found to be energetically more stable than the boat one, while both C1F's exhibit semiconducting behavior due to the sp3-hybridized C atoms. For the half-fluorinated BLG (C2F), two configurations, namely, C 2F-1 and C2F-3, are energetically favored. The electronic characteristics of the half-fluorinated BLG depend sensitively on its atomic configurations. The C2F-1 exhibits a semiconducting nature, while C2F-3 is metallic. In addition, the presence of a fluorine vacancy defect in fluorinated BLG is also studied. It is manifested that the nonfluorinated C atoms (sp2-hybridized) in the fluorinated BLGs are of remarkable significance in improving their electrical conductivity. © 2013 American Chemical Society.

Li X.D.,Xiamen University | Yu S.,Xiamen University | Wu S.Q.,Xiamen University | Wen Y.H.,Xiamen University | And 4 more authors.
Journal of Physical Chemistry C | Year: 2013

Hybrid systems consisting of graphene and various two-dimensional materials would provide more opportunities for achieving desired electronic and optoelectronic properties. Here, we focus on a superlattice composed of graphene and monolayer MoS2. The geometric and electronic structures of the superlattice have been studied by using density functional theory. The possible stacking models, which are classified into four types, are considered. Our results revealed that all the models of graphene/MoS2 superlattices exhibit metallic electronic properties. Small band gaps are opened up at the K-point of the Brillouin zone for all the four structural models. Furthermore, a small amount of charge transfer from the graphene layer to the intermediate region of C-S layers is found. The band structure and the charge transfer together with the buckling distortion of the graphene layer in the superlattice indicate that the interaction between the stacking sheets in the superlattice is more than just the van der Waals interaction. © 2013 American Chemical Society.

Zhou Y.,Fuzhou University | Zhang Y.,Fuzhou University | Zhang Y.,Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry | Lin M.,Fuzhou University | And 5 more authors.
Nature Communications | Year: 2015

Two-dimensional-layered heterojunctions have attracted extensive interest recently due to their exciting behaviours in electronic/optoelectronic devices as well as solar energy conversion systems. However, layered heterojunction materials, especially those made by stacking different monolayers together by strong chemical bonds rather than by weak van der Waal interactions, are still challenging to fabricate. Here the monolayer Bi2WO6 with a sandwich substructure of [BiO]+-[WO4]2-[BiO]+ is reported. This material may be characterized as a layered heterojunction with different monolayer oxides held together by chemical bonds. Coordinatively unsaturated Bi atoms are present as active sites on the surface. On irradiation, holes are generated directly on the active surface layer and electrons in the middle layer, which leads to the outstanding performances of the monolayer material in solar energy conversion. Our work provides a general bottom-up route for designing and preparing novel monolayer materials with ultrafast charge separation and active surface. © 2015 Macmillan Publishers Limited. All rights reserved.

Zhang P.,Xiamen University | Li X.D.,Xiamen University | Hu C.H.,Xiamen University | Wu S.Q.,Xiamen University | And 2 more authors.
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2012

Using density functional theory (DFT) with both the generalized gradient approximation (GGA) and hybrid functionals, we have investigated the structural, electronic and magnetic properties of a two-dimensional hydrogenated silicon-based material. The compounds, i.e. silicene, full- and half-hydrogenated silicene, are studied and their properties are compared. Our results suggest that silicene is a gapless semimetal. The coverage and arrangement of the absorbed hydrogen atoms on silicene influence significantly the characteristics of the resulting band structures, such as the direct/indirect band gaps or metallic/semiconducting features. Moreover, it is interesting to see that half-hydrogenated silicene with chair-like structure is shown to be a ferromagnetic semiconductor. © 2012 Elsevier B.V. All rights reserved.

Liu H.Y.,Jimei University | Hou Z.F.,Xiamen University | Hu C.H.,Xiamen University | Yang Y.,Xiamen University | And 2 more authors.
Journal of Physical Chemistry C | Year: 2012

We have studied the electronic and magnetic properties of fluorinated graphene with different coverage of fluorine using first-principles calculations based on the density functional theory. The atomic structures, adsorption energies, and electronic structures of fluorinated graphene are investigated. Our results show that the electronic and magnetic properties of fluorinated graphene sheet exhibit strong dependence on the degree of fluorination. A precise adsorption of fluorine enables a tuning of the band gap from 0 to ∼3.13 eV as well as a transformation from nonmagnetic semimetal to nonmagnetic/magnetic metal, or to magnetic/nonmagnetic semiconductor. Therefore, our study suggests that the property of graphene can be modified by absorbing different amounts of fluorine. © 2012 American Chemical Society.

Wang B.,Hebrew University of Jerusalem | Usharani D.,Hebrew University of Jerusalem | Usharani D.,Indian Central Food Technological Research Institute | Li C.,CAS Fujian Institute of Research on the Structure of Matter | And 2 more authors.
Journal of the American Chemical Society | Year: 2014

DNA-base lesions cause cancer and propagate into the genome. We use in-protein QM/MM calculations to study the repair of etheno-bridged adenine (εA) by the iron(IV)-oxo species of AlkB enzymes. Recent experimental investigations, using mass-spectrometry and in crystallo isolation, suggested that εA was repaired by formation of an epoxide (εA-ep) that further transforms to a glycol (εA-gl), ending finally in adenine and glyoxal. Theory reproduces the experimentally observed barrier for the rate-determining step and its pH dependence. However, as we show, the mass-spectrometrically identified species are side-byproducts unassociated with the repair mechanism. The repair is mediated by a zwitterionic species, of the same molecular mass as the epoxide, which transforms to an intermediate that matches the in crystallo trapped species in structure and mass, but is NOT the assumed εA-gl iron-glycol complex. Verifiable/falsifiable predictions, regarding the key protein residues, follow. The paper underscores the indispensable role of theory by providing atomistic descriptions of this vital mechanism, and guiding further experimental investigations. © 2014 American Chemical Society.

Usharani D.,Hebrew University of Jerusalem | Lai W.,Renmin University of China | Li C.,CAS Fujian Institute of Research on the Structure of Matter | Li C.,Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry | And 3 more authors.
Chemical Society Reviews | Year: 2014

This is a tutorial on the usage of valence bond (VB) diagrams for understanding chemical reactivity in general, and hydrogen atom transfer (HAT) reactivity in particular. The tutorial instructs the reader how to construct the VB diagrams and how to estimate HAT barriers from raw data, starting with the simplest reaction H + H2 and going all the way to HAT in the enzyme cytochrome P450. Other reactions are treated as well, and some unifying principles are outlined. The tutorial projects the unity of reactivity treatments, following Coulson's dictum "give me insight, not numbers", albeit with its modern twist: giving numbers and insight. This journal is © the Partner Organisations 2014.

Ma X.,CAS Fujian Institute of Research on the Structure of Matter | Hu S.-M.,CAS Fujian Institute of Research on the Structure of Matter | Tan C.-H.,CAS Fujian Institute of Research on the Structure of Matter | Zhang Y.-F.,Fuzhou University | And 4 more authors.
Inorganic Chemistry | Year: 2013

Cis- and trans-isomeric heterotrinuclear-metallic complexes and their two-electron-oxidation products, cis-/trans-[Cp(dppe)Fe(μ-CN)Ru(bpy) 2(μ-CN)Fe(dppe)Cp][PF6]2 (cis-/trans-1[PF6]2) and cis-/trans-[Cp(dppe)Fe(μ-CN) Ru(bpy)2(μ-CN)Fe(dppe)Cp][PF6]4 (cis-/trans-1[PF6]4), have been synthesized and structurally characterized. To the best of our knowledge, the complexes are the first example of a cis-/trans-isomer with multistates. Although separated by the diamagnetic cyanido-metal bridge, the two distant paramagnetic metal centers in both the oxidized complexes exhibit quite strong magnetic couplings. As a unique example, cis-1[PF6]4 is antiferromagnetic, and trans-1[PF6]4 is ferromagnetic. Density functional theory (DFT) calculations suggest that the spin-delocalization mechanism should be responsible for the magnetic interactions between the two distant paramagnetic Fe(III) centers across the diamagnetic cyanido-metal in both cis- and trans-14+. Most importantly, the DFT calculations revealed that the type (antiferromagnetic or ferromagnetic) and strength (J) of the magnetic interactions in such compounds can be controlled by the variation (cis or trans) of the diamagnetic central metal configurations. © 2013 American Chemical Society.

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