A series of novel AgCl/AgaCO3 heterostructured photocatalysts with different AgCl contents （5 wt%, 10 wt%, 20 wt%, and 30 wt%） were prepared by facile coprecipitation method at room temperature. The resulting produc...A series of novel AgCl/AgaCO3 heterostructured photocatalysts with different AgCl contents （5 wt%, 10 wt%, 20 wt%, and 30 wt%） were prepared by facile coprecipitation method at room temperature. The resulting products were characterized by powder X-ray diffraction （XRD）, scanning electron microscopy （SEM）, X-ray photoelectron spectroscopy （XPS）, and ultraviolet-visible diffuse reflectance spectroscopy （UV-Vis DRS）, respectively. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of methyl orange （MO） under UV light irradiation. With the optimal AgCl content of 20 wt%, the AgCl/AgECO3 composite exhibits the greatest enhancement in photocatalytic degradation efficiency. Its first-order reaction rate constant （0.67 h^-1） is 5.2 times faster than that of Ag2CO3 （0.13 h^-1）, and 16.8 times faster than that of AgCl （0.04 h^-1）. The formation of AgCl/AgaCO3 heterostructure could effectively suppress the recombination of the photo-generated electron and hole, resulting in an increase in photocatalytic activity.展开更多
Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for ...Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for Pd n （n=1-5） clusters adsorbed on TiO2 （110） surface based on DFT-GGA calculations utilizing periodic supercell models.A single Pd adatom on the defect-free surface prefers to adsorb at a hollow site bridging a protruded oxygen and a five-fold titanium atom along the [110] direction,while Pd dimer is located on the channels with the Pd-Pd bond parallel to the surface.According to the transition states （TSs） search,the adsorbed Pd trimer tends to triangular growth mode,rather than linear mode,while the Pd4 and Pd5 clusters prefer three-dimensional （3D） models.However,the oxygen vacancy has almost no influence on the promotion of Pd n cluster nucleation.Additionally,of particular significance is that the Pd-TiO2 interaction is the main driving force at the beginning of Pd nucleation,whereas the Pd-Pd interaction gets down to control the growth process of Pd cluster as the cluster gets larger.It is hoped that our theoretical study would shed light on further designing high-performance TiO2 supported Pd-based catalysts.展开更多
Carbon dioxide adsorbed on different kinds of CaO surfaces has been investigated with the help of the first principle density functional theory plane wave calculations. Various possible configurations have been consid...Carbon dioxide adsorbed on different kinds of CaO surfaces has been investigated with the help of the first principle density functional theory plane wave calculations. Various possible configurations have been considered and the calculated results showed that CO2 was strongly adsorbed by C atom bonded with the CaO （001） and （110） surfaces with adsorption energies of 1.38 and 3.22 eV, respectively. The adsorption of CO2 molecule on defect surfaces is complicated compared with that on the pristine surfaces. The adsorption energy of CO2 absorbed on the CaO（110） surface is larger than that of CaO（001） surface when the type of defect surface is the same.展开更多
Density functional theory and GGA-PW91 exchange correlation function were performed to simulate the bonding behavior of hydroxyl and epoxy groups on the graphene surface. We compared the different binding energies for...Density functional theory and GGA-PW91 exchange correlation function were performed to simulate the bonding behavior of hydroxyl and epoxy groups on the graphene surface. We compared the different binding energies for two epoxy groups, as well as one hydroxyl group and one epoxy group on all possible positions within a 6-fold ring, respectively. The calculated results suggest that two oxygen-containing groups always tend to bind with the neighboring carbon atoms at the opposite sides. Moreover, two hydroxyl groups on the meta position are unstable, and one of the hydroxyl groups easily migrates to the para position. In contrast to the disperse arrangement, the aggregation of multiply hydroxyl groups largely enhances the binding energy of every hydroxyl group. It is worth noting that the binding sites and hydrogen bonds play an important role in stability. Our work further points out the number of oxygen-containing groups and the location of oxide region largely influence the electronic properties of graphene oxide.展开更多
Density functional theory calculations have been performed to study the interaction of small silver clusters, Ag2-Ag9, with HCN. The adsorption of HCN on-top site of the silver cluster, among various possible sites, i...Density functional theory calculations have been performed to study the interaction of small silver clusters, Ag2-Ag9, with HCN. The adsorption of HCN on-top site of the silver cluster, among various possible sites, is energetically preferred. The adsorption energies of HCN on the silver clusters reach a local maximum at n = 4, which is only about 0.450 eV, indicating that the adsorbed HCN molecule is weakly perturbed. The adsorbed C-N and C-H stretching frequencies are blue- and red-shifted compared with the values of free HCN, respectively.展开更多
Nanocrystalline MTiO3 （M = St, Pb, Co） were prepared by a general self-pro- pagating combustion method. The samples were characterized by X-ray diffraction （XRD） analysis, scanning electron microscopy （SEM）, tra...Nanocrystalline MTiO3 （M = St, Pb, Co） were prepared by a general self-pro- pagating combustion method. The samples were characterized by X-ray diffraction （XRD） analysis, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, N2 adsorption and UV-vis diffuse reflectance spectra （DRS）. The photocatalytic activity of MTiO3 （M = Sr, Pb, Co） was evaluated by the photocatalytic degradation of methyl orange （MO）. MTiO3 （M = Sr, Pb, Co） having the same core element showed distinctly different photocatalytic activity due to the different coordinating atoms. Factors affecting the photocatalytic activity of MTiO3 （M = Sr, Pb, Co） were discussed. It was suggested that the structures of TiO6 octahedra and the electronic property were the predominant factors of the photocatalytic behavior for MTiO3 （M = Sr, Pb, Co）.展开更多
A novel squaraine dye（SQ） modified by ferrocene has been synthesized through（E）-dodecyl-2-ferrocenyl vinyl-1H-pyrrole and squaric acid.The molecular structure of SQ was characterized by ~1H NMR,^（13）C NMR,MS and...A novel squaraine dye（SQ） modified by ferrocene has been synthesized through（E）-dodecyl-2-ferrocenyl vinyl-1H-pyrrole and squaric acid.The molecular structure of SQ was characterized by ~1H NMR,^（13）C NMR,MS and elemental analysis.SQ is high soluble in common solvents.The maximum absorptions of SQ in different solvents are in the range of 708-734 nm,exhibiting positive solvatochromism with increasing solvent polarity.The optical and electrical properties of SQ indicate that it is a promising electron donor material for bulk-heterojunction organic solar cell.展开更多
Based on density functional theory and generalized gradient approximation calculations, the adsorption of Co2B2 and Ni2B2 clusters on the rutile TiO2 （110） surface has been investigated utilizing periodic supercell ...Based on density functional theory and generalized gradient approximation calculations, the adsorption of Co2B2 and Ni2B2 clusters on the rutile TiO2 （110） surface has been investigated utilizing periodic supercell models. Unambiguously, the results demonstrate that the hollow site turns out to be preferable for Co2B2 cluster while Ti2 site is for Ni2B2 cluster to adsorb. Orbital population analysis indicates a strong interaction between Co2B2 and O atom of TiO2 surface, which can be attributed to the overlap of Co 3d and surface O 2p orbital. Similarly, for Ni2B2 , the bonding interaction occurs mostly through the interaction of Ni 3d/4s and O 2p orbitals. Note that, there is also an interaction within the Co2B2 clusters （Ni2B2） through B 2s/2p and Co 3d orbitals （Ni 3d/4s）. Moreover, orbital analysis results shows that the strong bonding between Ni2B2 and Ti2 site is due to the overlap of HOMO of Ni2B2 and d-orbital of five-coordinated titanium atoms.展开更多
We applied periodic density-functional theory to investigate the adsorption of C2H2 on the Cu/Pt bimetallic and monometallic surfaces, including Cu-Pt-Pt and Pt--Cu-Pt representing the monolayer Cu on the Pt surface a...We applied periodic density-functional theory to investigate the adsorption of C2H2 on the Cu/Pt bimetallic and monometallic surfaces, including Cu-Pt-Pt and Pt--Cu-Pt representing the monolayer Cu on the Pt surface and subsurface Cu in the Pt surface, respectively. For the Pt（111） and Pt-Cu-Pt surfaces, C2H2 is preferentially a 3-fold “parallel-bridge” configuration, and a ＂p-bridge＂ structure exists above the Cu（111） and Cu-Pt-Pt surfaces. The adsorption energy of C2H2 on these surfaces decreases in the order Pt（111） 〉 Cu-Pt-Pt 〉 Pt-Cu-Pt 〉 Cu（11）. The analysis of density of states, charge, and vibrational frequencies showed obviously weakening of the adsorbed C-C bond and high sp2 character on the carbon atom. Furthermore, when the top-layer compositions are equal, the nearer the EF d-band center is, the larger the C2H2 adsorption energy will be.展开更多
Sphere-like mesoporous CdS nanocrystals with high crystallinity and big surface area were successfully fabricated by ultrasound irradiation at room temperature.The as-synthesized CdS with and without ultrasound irra d...Sphere-like mesoporous CdS nanocrystals with high crystallinity and big surface area were successfully fabricated by ultrasound irradiation at room temperature.The as-synthesized CdS with and without ultrasound irra diation was investigated by the characterizations of X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and Brunauer-Emmett-Teller(BET)surface areas.The photocatalytic acti vity of the CdS was evaluated by photocatalytic degradation of methyl orange under visible light(λ〉420 nm)irradia tion.A possible mechanism for the formation of the CdS nanocrystals with mesoporous structure under ultrasound irradiation was proposed.The results show that both the template role of the triblock copolymer of P123 and the effect of ultrasound-induced aggregation are mainly responsible for the formation of mesoporous structure.On the other hand,the energy generated from acoustic cavitation can effectively accelerate the crystallization process of the amorphous CdS.展开更多
Flake BiOBr was first prepared by a solution method at room temperature. Then, the produced BiOBr was calcined at different temperatures. It was found that BiOBr is not a stable compound. It transforms to plate-like B...Flake BiOBr was first prepared by a solution method at room temperature. Then, the produced BiOBr was calcined at different temperatures. It was found that BiOBr is not a stable compound. It transforms to plate-like Bi24031Brll at around 750 ℃ and the formed Bi24O31Br11 can further convert to rod-like a-Bi203 at around 850℃. The prepared compounds were characterized with X-ray diffraction （XRD）, N2 physical adsorption, scanning electron microscopy （SEM）, and UV-Vis diffuse reflectance spectra （DRS）, respectively. The photocatalytic activity of the produced bismuth oxybromides was evaluated by photocatalytic decomposition of acid orange Ⅱ under both visible light （λ〉420 nm） and UV light （λ=365 nm） irradiation. Results show that these compounds have different band gaps and different photocatalytic properties. The band gap energies of the as-prepared samples were found to be 2.82, 2.79, 2.60 and 3.15 eV for BiOBr, BiOBr/Bi24O31Br, Bi24O31Br, and a-Bi2O3, respectively. Under both UV light and visible light irradiation, the photocatalytic activity follows the order： BiOBr/Bi24O31Br mixture 〉 BiOBr 〉 Bi24031Br〉a-Bi2O3. The change in photocatalytic activity could be attributed to the different light absorption ability and microstructures of the photocatalysts.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.21067004 and21263005)the Young Science and Technology Project of Jiangxi Province Natural Science Foundation(No.20133BAB21003)+1 种基金the Young Scientist Training Project of Jiangxi Province(No.20122BCB23015)the Science and Technology Landing Project of Jiangxi Province Education Office(No.KJLD14046)
文摘A series of novel AgCl/AgaCO3 heterostructured photocatalysts with different AgCl contents （5 wt%, 10 wt%, 20 wt%, and 30 wt%） were prepared by facile coprecipitation method at room temperature. The resulting products were characterized by powder X-ray diffraction （XRD）, scanning electron microscopy （SEM）, X-ray photoelectron spectroscopy （XPS）, and ultraviolet-visible diffuse reflectance spectroscopy （UV-Vis DRS）, respectively. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of methyl orange （MO） under UV light irradiation. With the optimal AgCl content of 20 wt%, the AgCl/AgECO3 composite exhibits the greatest enhancement in photocatalytic degradation efficiency. Its first-order reaction rate constant （0.67 h^-1） is 5.2 times faster than that of Ag2CO3 （0.13 h^-1）, and 16.8 times faster than that of AgCl （0.04 h^-1）. The formation of AgCl/AgaCO3 heterostructure could effectively suppress the recombination of the photo-generated electron and hole, resulting in an increase in photocatalytic activity.
基金supported by the National Natural Science Foundation of China (90922022)the Foundation of State Key Laboratory of Coal Combustion of Huazhong University of Science and Technology (FSKLCC1110)the Natural Science Foundation of Fujian Province,China (2012J01032,2012J01041)
文摘Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for Pd n （n=1-5） clusters adsorbed on TiO2 （110） surface based on DFT-GGA calculations utilizing periodic supercell models.A single Pd adatom on the defect-free surface prefers to adsorb at a hollow site bridging a protruded oxygen and a five-fold titanium atom along the [110] direction,while Pd dimer is located on the channels with the Pd-Pd bond parallel to the surface.According to the transition states （TSs） search,the adsorbed Pd trimer tends to triangular growth mode,rather than linear mode,while the Pd4 and Pd5 clusters prefer three-dimensional （3D） models.However,the oxygen vacancy has almost no influence on the promotion of Pd n cluster nucleation.Additionally,of particular significance is that the Pd-TiO2 interaction is the main driving force at the beginning of Pd nucleation,whereas the Pd-Pd interaction gets down to control the growth process of Pd cluster as the cluster gets larger.It is hoped that our theoretical study would shed light on further designing high-performance TiO2 supported Pd-based catalysts.
基金supported by the National Natural Science Foundation of China(21203027,21073035)Natural Science Foundation of Fujian Province for Distinguished Young Investigator Grant(2013J06004)Funds of Fujian Province(2012J01032,2012J01041)
文摘Carbon dioxide adsorbed on different kinds of CaO surfaces has been investigated with the help of the first principle density functional theory plane wave calculations. Various possible configurations have been considered and the calculated results showed that CO2 was strongly adsorbed by C atom bonded with the CaO （001） and （110） surfaces with adsorption energies of 1.38 and 3.22 eV, respectively. The adsorption of CO2 molecule on defect surfaces is complicated compared with that on the pristine surfaces. The adsorption energy of CO2 absorbed on the CaO（110） surface is larger than that of CaO（001） surface when the type of defect surface is the same.
基金supported by the Foundation of State Key Laboratory of Coal Combustion of Huazhong University of Science and Technology(FSKLCC1110)the Natural Science Foundation of Fujian Province(2012J01032,2012J01041)
文摘Density functional theory and GGA-PW91 exchange correlation function were performed to simulate the bonding behavior of hydroxyl and epoxy groups on the graphene surface. We compared the different binding energies for two epoxy groups, as well as one hydroxyl group and one epoxy group on all possible positions within a 6-fold ring, respectively. The calculated results suggest that two oxygen-containing groups always tend to bind with the neighboring carbon atoms at the opposite sides. Moreover, two hydroxyl groups on the meta position are unstable, and one of the hydroxyl groups easily migrates to the para position. In contrast to the disperse arrangement, the aggregation of multiply hydroxyl groups largely enhances the binding energy of every hydroxyl group. It is worth noting that the binding sites and hydrogen bonds play an important role in stability. Our work further points out the number of oxygen-containing groups and the location of oxide region largely influence the electronic properties of graphene oxide.
基金supported by the National Natural Science Foundation of China(21203027,21073035,21373048)Funds of Fujian Province(2012J01032,2012J01041)Fuzhou University(2012-XQ-11)
文摘Density functional theory calculations have been performed to study the interaction of small silver clusters, Ag2-Ag9, with HCN. The adsorption of HCN on-top site of the silver cluster, among various possible sites, is energetically preferred. The adsorption energies of HCN on the silver clusters reach a local maximum at n = 4, which is only about 0.450 eV, indicating that the adsorbed HCN molecule is weakly perturbed. The adsorbed C-N and C-H stretching frequencies are blue- and red-shifted compared with the values of free HCN, respectively.
基金financially supported by the Educational Commission of Fujian Province(No. JB11005)Fund for Fostering Excellent Young Key Teachers of Fujian Normal University (fjsdjk2012067)
文摘Nanocrystalline MTiO3 （M = St, Pb, Co） were prepared by a general self-pro- pagating combustion method. The samples were characterized by X-ray diffraction （XRD） analysis, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, N2 adsorption and UV-vis diffuse reflectance spectra （DRS）. The photocatalytic activity of MTiO3 （M = Sr, Pb, Co） was evaluated by the photocatalytic degradation of methyl orange （MO）. MTiO3 （M = Sr, Pb, Co） having the same core element showed distinctly different photocatalytic activity due to the different coordinating atoms. Factors affecting the photocatalytic activity of MTiO3 （M = Sr, Pb, Co） were discussed. It was suggested that the structures of TiO6 octahedra and the electronic property were the predominant factors of the photocatalytic behavior for MTiO3 （M = Sr, Pb, Co）.
基金the National Natural Science Foundation of China(No20702005)the Fujian Provincial Natural Science Foundation of China(No2008J0148)
文摘A novel squaraine dye（SQ） modified by ferrocene has been synthesized through（E）-dodecyl-2-ferrocenyl vinyl-1H-pyrrole and squaric acid.The molecular structure of SQ was characterized by ~1H NMR,^（13）C NMR,MS and elemental analysis.SQ is high soluble in common solvents.The maximum absorptions of SQ in different solvents are in the range of 708-734 nm,exhibiting positive solvatochromism with increasing solvent polarity.The optical and electrical properties of SQ indicate that it is a promising electron donor material for bulk-heterojunction organic solar cell.
基金supported by the Foundation of State Key Laboratory of Coal Combustion of Huazhong University of Science and Technology (FSKLCC1110)the Natural Science Foundation of Fujian Province (2012J01032, 2012J01041)
文摘Based on density functional theory and generalized gradient approximation calculations, the adsorption of Co2B2 and Ni2B2 clusters on the rutile TiO2 （110） surface has been investigated utilizing periodic supercell models. Unambiguously, the results demonstrate that the hollow site turns out to be preferable for Co2B2 cluster while Ti2 site is for Ni2B2 cluster to adsorb. Orbital population analysis indicates a strong interaction between Co2B2 and O atom of TiO2 surface, which can be attributed to the overlap of Co 3d and surface O 2p orbital. Similarly, for Ni2B2 , the bonding interaction occurs mostly through the interaction of Ni 3d/4s and O 2p orbitals. Note that, there is also an interaction within the Co2B2 clusters （Ni2B2） through B 2s/2p and Co 3d orbitals （Ni 3d/4s）. Moreover, orbital analysis results shows that the strong bonding between Ni2B2 and Ti2 site is due to the overlap of HOMO of Ni2B2 and d-orbital of five-coordinated titanium atoms.
基金supported by the National Natural Science Foundation of China (21203027, 21073035)Funds of Fujian Province (2012J01032, 2012J01041)Scientific Development Fund of Fuzhou University (2012-XQ-11)
文摘We applied periodic density-functional theory to investigate the adsorption of C2H2 on the Cu/Pt bimetallic and monometallic surfaces, including Cu-Pt-Pt and Pt--Cu-Pt representing the monolayer Cu on the Pt surface and subsurface Cu in the Pt surface, respectively. For the Pt（111） and Pt-Cu-Pt surfaces, C2H2 is preferentially a 3-fold “parallel-bridge” configuration, and a ＂p-bridge＂ structure exists above the Cu（111） and Cu-Pt-Pt surfaces. The adsorption energy of C2H2 on these surfaces decreases in the order Pt（111） 〉 Cu-Pt-Pt 〉 Pt-Cu-Pt 〉 Cu（11）. The analysis of density of states, charge, and vibrational frequencies showed obviously weakening of the adsorbed C-C bond and high sp2 character on the carbon atom. Furthermore, when the top-layer compositions are equal, the nearer the EF d-band center is, the larger the C2H2 adsorption energy will be.
基金Supported by the National Natural Science Foundation of China(No.21067004)the Natural Science Foundation of Jiangxi Province,China(No.2010GZH0048)the Open Foundation of State Key Laboratory of Physical Chemistry of Solid Surfaces,Xiamen University,China(No.200906)
文摘Sphere-like mesoporous CdS nanocrystals with high crystallinity and big surface area were successfully fabricated by ultrasound irradiation at room temperature.The as-synthesized CdS with and without ultrasound irra diation was investigated by the characterizations of X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and Brunauer-Emmett-Teller(BET)surface areas.The photocatalytic acti vity of the CdS was evaluated by photocatalytic degradation of methyl orange under visible light(λ〉420 nm)irradia tion.A possible mechanism for the formation of the CdS nanocrystals with mesoporous structure under ultrasound irradiation was proposed.The results show that both the template role of the triblock copolymer of P123 and the effect of ultrasound-induced aggregation are mainly responsible for the formation of mesoporous structure.On the other hand,the energy generated from acoustic cavitation can effectively accelerate the crystallization process of the amorphous CdS.
文摘Flake BiOBr was first prepared by a solution method at room temperature. Then, the produced BiOBr was calcined at different temperatures. It was found that BiOBr is not a stable compound. It transforms to plate-like Bi24031Brll at around 750 ℃ and the formed Bi24O31Br11 can further convert to rod-like a-Bi203 at around 850℃. The prepared compounds were characterized with X-ray diffraction （XRD）, N2 physical adsorption, scanning electron microscopy （SEM）, and UV-Vis diffuse reflectance spectra （DRS）, respectively. The photocatalytic activity of the produced bismuth oxybromides was evaluated by photocatalytic decomposition of acid orange Ⅱ under both visible light （λ〉420 nm） and UV light （λ=365 nm） irradiation. Results show that these compounds have different band gaps and different photocatalytic properties. The band gap energies of the as-prepared samples were found to be 2.82, 2.79, 2.60 and 3.15 eV for BiOBr, BiOBr/Bi24O31Br, Bi24O31Br, and a-Bi2O3, respectively. Under both UV light and visible light irradiation, the photocatalytic activity follows the order： BiOBr/Bi24O31Br mixture 〉 BiOBr 〉 Bi24031Br〉a-Bi2O3. The change in photocatalytic activity could be attributed to the different light absorption ability and microstructures of the photocatalysts.
