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Chen F.,Ningde Normal University | Yan G.,Ningde Normal University | Yan G.,Research Institute of Photocatalysis | Zheng L.,Fujian Normal University | And 5 more authors.
Journal of Materials and Environmental Science | Year: 2015

Silver, carbon-doped TiO2 absorbent was obtained using hydrothermal method with titanium sulfate as a titanium source. Reactive brilliant red X-3B was used as a target degradation material to evaluate its adsorption activity. Physicochemical properties of the absorbent was characterized by analytical techniques such as XRD, SEM-EDS, TG-DTG, TEM-HRTEM, BET, and XPS. The results showed that the synthesized samples has a phase of anatase with typical mesoporous structure, and it also has a good adsorption activity of reactive brilliant red X-3B. The Ag-C-TiO2 (calcined at 500°C) absorbent's discoloration rate for reactive brilliant red X-3B (50 ppm) reached 97% after adsorption for 60minutes at absorbent of 1.5 g/L(50 ppm reactive brilliant red X-3B solution), and solution pH of 7~9. This type of Ag-C co-doped TiO2 could potentially be used as absorbent for dye wastewater treatment based on its unique physicochemical properties.

Jin H.,Fuzhou University | Zhu J.,Fuzhou University | Hu J.,Fuzhou Command Academy | Li Y.,Fuzhou University | And 6 more authors.
Theoretical Chemistry Accounts | Year: 2011

Geometries and electronic structures of WO3(001) surface and a series of stoichiometric (WO3)n clusters (n = 1-6) have been systematically investigated using first-principles density functional calculations. Six possible reconstructured models of WO3(001) surface with cubic phase are explored, and the most stable configuration is the (√2×√2)R45° surface. The main feature of WO3(001) surface is that the top of valence band is dominated by the 2p states of the bridging oxygen atom, rather than the top terminal oxygen. By comparing the geometrical parameters, from the structural point of view, the W3O9 cluster can be used as the smallest molecular prototype of the WO3 surface. However, in terms of the electronic structure, only until W6O18, the cluster begins to appear the electronic feature of the WO3(001) surface. This may be due to the reason that the W6O18 cluster and the top layer of WO3(001) surface show similar "stoichiometry" if we treat two kinds of oxygen atoms as different "elements". In addition, for the chemical reactivity, using BH3 as a probe molecule, the W6O18 cluster also bears general resemblance to the WO3(001) surface, and the bridging oxygen atoms in two systems are the preferred sites for the nucleophilic reaction. Therefore, our results indicate that the W6O18 cluster with a spherical buckyball structure can be viewed as the smallest molecular model to understand the properties such as catalytic activity of WO3(001) surface. © 2011 Springer-Verlag.

Zhu J.,Fuzhou University | Jin H.,Fuzhou University | Zang L.,Fuzhou University | Li Y.,Fuzhou University | And 7 more authors.
Journal of Physical Chemistry C | Year: 2011

A series of nonstoichiometric tritungsten oxide clusters W 3On (n = 7, 8, 10) deposited on the TiO2(110) surface have been investigated by using first-principles DFT calculations. Various possible configurations have been considered for each W 3On/TiO2(110) system, based upon ab initio molecular dynamics simulations and thermodynamical analyses. After deposition of the W3On cluster, the position of the Fermi level is sensitive to the stoichiometry of the cluster. This is due to the obvious charge transfer occurring from the oxygen-deficient W3On cluster (n < 9) to the TiO2(110) surface, whereas the direction of charge transfer is reversed for the deposition of the oxygen-enriched W 3On cluster (n > 9). Our results clearly indicate that the deposition of clusters with different stoichiometric compositions offers an opportunity to control the properties of the support, including the conductivity, the surface work function, and the catalytic performance over a sufficient range. In addition, our results show that the relative stability of nonstoichiometric tritungsten oxide clusters in the gas phase is not preserved after landing on the TiO2(110) surface. Therefore, from a thermodynamical point of view, it may provide a possible way to stabilize the unstable clusters in the gas phase by choosing a suitable support. © 2011 American Chemical Society.

Zhu J.,Fuzhou University | Lin S.,Fuzhou University | Wen X.,Fuzhou University | Fang Z.,Fuzhou University | And 9 more authors.
Journal of Chemical Physics | Year: 2013

Periodic density functional theory calculations have been performed to study the most stable structure of the (WO3)3 nanocluster deposited on the MgO(001) surface with three kinds of FS centers (FS 0, FS +, and FS 2+). Our results indicate that the configuration of (WO 3)3 cluster, including the cyclic conformation and the heights of three W atoms, and the oxidation states are sensitive to the charge state of the FS center. It is interesting that the electron-riched FS 0 vacancy on the MgO(001) surface can act as a promoting site to enhance the W-W interaction and the W3O3 cyclic conformation is maintained, while the skeleton of cluster becomes flexible when (WO3)3 is adsorbed on the electron-deficient vacancy (FS + and FS 2+). Accordingly, three FS-centers exhibit different arrangements of X-ray photoelectron spectra, the scanning tunneling microscopy images, and the vibrational spectra after depositing (WO3)3 cluster. Present results reveal that the (WO3)3 cluster may be used as a probe to identify the different FS centers on the MgO(001) surface. © 2013 American Institute of Physics.

Huang X.-H.,Fuzhou University | Huang X.-H.,Research Institute of Photocatalysis | Huang X.-H.,CAS Fujian Institute of Research on the Structure of Matter | Xiao Z.-P.,Fuzhou University | And 4 more authors.
Journal of Coordination Chemistry | Year: 2015

(Figure Presented). Two silver(I) compounds, [Ag(H2mbpz)(Hchda)]n (1) and [Ag2(H2mbpz)2(oba)]n (2) (where H2mbpz = 3,3′,5,5′-tetramethyl-4,4′-bipyrazole, H2chda = trans-cyclohexane-dicarboxylic acid and H2oba = 4,4′-oxy-bis-benzoic acid), have been synthesized and characterized by single-crystal X-ray diffraction analyses. In both cases, the Ag(I) centers are linked by H2mbpz ligands to form 1-D Ag(I)-H2mbpz chains; then, the Ag(I)-H2mbpz chains connect with two neighboring congeners through Ag⋯Ag interactions, forming 2-D supramolecular layers. In 1, the dicarboxylate is monodeprotonated and linked to form an anion chain through strong hydrogen bonding interaction. Such anion chains attach on two sides of the supramolecular layers via Ag-O bonds to form a neutral sandwich-like layered network. In 2, the dicarboxylate is fully deprotonated and adopts a μ2-η1:η1 mode to link two adjacent supramolecular layers to form a twofold interpenetrating 3-D supramolecular network. The thermal stability and luminescence of 1 were also studied. © 2015 Taylor & Francis.

Jin H.,Fuzhou University | Zhu J.,Fuzhou University | Chen W.,Fuzhou University | Fang Z.,Fuzhou University | And 7 more authors.
Journal of Physical Chemistry C | Year: 2012

The γ-WO 3(001) surfaces doped by a series of group VB elements have been investigated by means of first-principles density functional theory (DFT) calculations combined with a slab model. Our results show that the doping of VB element is preferential under O-rich growth conditions and that the replacement of tungsten by Ta atom is energetically favorable among three group VB elements. The introduction of a group VB atom into the surface results in the downward shift of the Fermi level, and in most cases, the 2p states derived from the in-plane oxygen atom are still the dominate components at the Fermi level as before doping. However, the substitution of Ta dopant for 6-fold-coordinated tungsten atom (W 6f) at the top layer is a special case in which the 2p states of the top terminal oxygen atom just above Ta become the primary compositions at the Fermi level. Only in this model, the spin densities are mainly located on the terminal oxygen atoms near the Ta site, and the oxygen radical center observed in the gas-phase W 3O 9 + cluster is reproduced. Therefore, the formation of radical oxygen center in the condensed phase depends on not only the substituent site but also the type of the dopant. Moreover, additional calculations are performed to study the oxidation reaction of CO molecule on the above Ta doped surface, and results indicate that the energy barrier for CO oxidization is obviously reduced compared to the undoped one, which implies that the introduction of Ta at W 6f site can efficiently improve the oxidation reactivity of the WO 3(001) surface. © 2012 American Chemical Society.

Jin H.,Fuzhou University | Jin H.,Yichun University | Lin W.,University of California at San Diego | Zhang Y.,Fuzhou University | And 7 more authors.
Theoretical Chemistry Accounts | Year: 2012

A series of Ti-doped SnO 2(110) surfaces with different oxygen vacancies have been investigated by means of first principles DFT calculations combined with a slab model. Three kinds of defective SnO 2(110) surfaces are considered, including the formations of bridging oxygen (O b) vacancy, in-plane oxygen (O i) vacancy, and the coexistence of O b and O i vacancies. Our results indicate that Ti dopant prefers the fivefold-coordinated Sn site on the top layer for the surface with O b or O i vacancy, while the replacement of sublayer Sn atom becomes the most energetically favorable structure if the O b and O i vacancies are presented simultaneously. Based on analyzing the band structure of the most stable configuration, the presence of Ti leads to the variation of the band gap state, which is different for three defective SnO 2(110) surfaces. For the surface with O b or O i vacancy, the component of the defect state is modified, and the reaction activity of the corresponding surface is enhanced. Hence, the sensing performance of SnO 2 may be improved after introducing Ti dopant. However, for the third kind of reduced surface with the coexistence of O b and O i vacancies, the sublayer doping has little influence on the defect state, and only in this case, the Ti doping state partly appears in the band gap of SnO 2(110) surface. © 2012 Springer-Verlag.

Ding K.-N.,Fuzhou University | Ding K.-N.,Research Institute of Photocatalysis | Li Y.-L.,Fuzhou University | Zhang Y.-F.,Fuzhou University
Jiegou Huaxue | Year: 2014

The electronic structures and optical properties of II-III 2-VI4 (II = Zn, Cd; III = In; VI = Se, Te) compounds are studied by the density functional theory (DFT) using the Vienna ab initio simulation package (VASP). Geometrical optimization of the unit cell is in good agreement with the experimental data. Our calculations show that the valence band maximum (VBM) and conduction band minimum (CBM) are located at G resulting in a direct energy gap. The optical properties are analyzed, and the independent second harmonic generation (SHG) coefficients are determined. By an analysis of the band structure, we can get that SHG response of the system can be attributed to the transitions from the bands near the top of valence band that are derived from the Se/Te p states to the unoccupied bands contributed by the p states of In atoms.

Ding K.-N.,Fuzhou University | Ding K.-N.,Research Institute of Photocatalysis | Li Y.-L.,Fuzhou University | Li Y.-L.,Research Institute of Photocatalysis | And 2 more authors.
Jiegou Huaxue | Year: 2014

The first-principles calculations were performed to investigate the stability, band structure, density of states and redox potential of Al-, Ga-, and In-doped monoclinic BiVO4 (mBiVO4). The calculated formation energies show that Al-doped mBiVO4 inducing an O vacancy is energetically favorable with a smaller defect formation value. With the incorporation of Al, Ga, and In, the band gap of the doped systems will be narrowed in the order of Al-doped < Ga-doped < In-doped mBiVO4, which is beneficial for the response to the visible light. And the substitution of an Al or Ga for a V atom will significantly enhance the reducibility of mBiVO4, improving the efficiency of H2 evolution from H2O. Our results show that the photocatalytic activity of mBiVO4 can be modulated by substitutional doping of Al, Ga, and In.

Song H.-Y.,Dalian University of Technology | Li G.,Dalian University of Technology | Wang X.-S.,Dalian University of Technology | Xu Y.-J.,Research Institute of Photocatalysis
Catalysis Today | Year: 2010

Au/Ti-HMS was prepared by in situ method, NH3 deposition-precipitation (NH3 DP) and urea deposition-precipitation (Urea DP), respectively. The catalysts were characterized by a series of techniques including ICP, powder XRD, N2 sorption, UV-visible spectroscopy, TEM and H2-TPR. Using n-octane containing BT, DBT and 4,6-DMDBT as model compound, the performance of the catalysts in oxidative desulfurization (ODS) using in situ generated H2O2 from H2 and O2 were investigated. The results show that preparation method influences porous structure of the support and gold particles size. In situ sample has maintained the intrinsic structure of Ti-HMS, whereas, the gold particles are not as uniform and small as that of DP sample. NH3 DP sample still possesses the wormhole structure of HMS despite the absence of typical XRD peak. The mesoporous structure of urea DP sample has been damaged seriously. Au3+ on outer surface of the support is easier to be reduced than that in pores, as confirmed by H2-TPR. In addition, the three samples exhibit different catalytic activities in ODS using in situ H2O2 as oxidant. For the removal of BT and DBT, Au/Ti-HMS (NH3 DP) exhibits the highest catalytic activities. Regarding the removal of 4,6-DMDBT, the optimum catalyst is Au/Ti-HMS (In situ); however, Au/Ti-HMS (Urea DP) nearly loses catalytic activity. © 2009 Elsevier B.V. All rights reserved.

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