The CO_2 adsorption on CaO(001) surface at different coverages from 1/9 monolayer(ML) to 1 ML has been investigated using density functional theory calculations. With the analysis of the most stable adsorption structu...The CO_2 adsorption on CaO(001) surface at different coverages from 1/9 monolayer(ML) to 1 ML has been investigated using density functional theory calculations. With the analysis of the most stable adsorption structures at different coverages, the mechanism of CaO(001)surface carbonating into CaCO_3 has been explored. At low coverages(≤1/3 ML), CO_2 molecule prefers sitting in parallel pattern on the CaO(001) surface, while the structure of the CaO(001)surface remains unchanged. At medium coverage(4/9 ～ 2/3 ML), the repulsive interactions between oxygen atoms of CO_2 become stronger, and the calcium carbonation structure appears on the CaO(001) surface. At high coverage( ≥ 7/9 ML), the structure of the CaO(001) surface is deeply damaged, and a few CO_2 molecules have penetrated into the surface and bound to the O atom of the second layer(sub-surface), eventually forming the layered structure of CaCO_3.Additionally, herein has discussed the simulation of HREELS and thermodynamical stability of these structures at different coverages.展开更多
The interaction of Ag atoms with a defective MgO（001） surface is systematically studied based on density functional theory. The Ag clusters are deposited on neutral and charged oxygen vacancies of the MgO（001） sur...The interaction of Ag atoms with a defective MgO（001） surface is systematically studied based on density functional theory. The Ag clusters are deposited on neutral and charged oxygen vacancies of the MgO（001） surface. The structures of Ag clusters take the shape of simple models of two- or three-dimensional （2D and 3D） metal particles deposited on the MgO surface. When the nucleation of the metal clusters occurs in the Fs （missing neutral O） centre, the interaction with the substrate is considerably stronger than that in the Fs^＋ （missing O-） centre. The results show that the adsorption of Ag atoms on the MgO surface with oxygcn vacancy is stronger than on a clear MgO surface, thereby attracting more Ag atoms to cluster together, and forming atomic islands.展开更多
Photocatalytic degradation of gaseous pollutants on Bi-based semiconductors under solar lightirradiation has attracted significant attention.However,their application in gaseous straight-chainalkane purification is st...Photocatalytic degradation of gaseous pollutants on Bi-based semiconductors under solar lightirradiation has attracted significant attention.However,their application in gaseous straight-chainalkane purification is still rare.Here,a series of Bi/BiOBr composites were solvothermally synthe-sized and applied in solar-light-driven photocatalytic degradation of gaseous n-hexane.The charac-terization results revealed that both increasing number of functional groups of alcohol solvent(from methanol and ethylene glycol to glycerol)and solvothermal temperature(from 160 and 180to 200℃)facilitated the in-situ formation of metallic Bi nanospheres on BiOBr nanoplates withexposed(110)facets.Meanwhile,chemical bonding between Bi and BiOBr was observed on theseexposed facets that resulted in the formation of surface oxygen vacancy.Furthermore,the synergis-tic effect of optimum surface oxygen vacancy on exposed(110)facets led to a high visible light re-sponse,narrow band gap,great photocurrent,low recombination rate of the charge carriers,andstrong·O2-and h*formation,all of which resulted in the highest removal efficiency of 97.4%within120 min of 15 ppmv of n-hexane on Bi/BiOBr.Our findings efficiently broaden the application ofBi-based photocatalysis technology in the purification of gaseous straight-chain pollutants emittedby the petrochemical industry.展开更多
Response surface methodology(RSM)was employed to optimize the control parameters of TiO_(2)/graphene with exposed{001}facets during synthesis,and its enhanced photocatalytic activities were evaluated in the photodegra...Response surface methodology(RSM)was employed to optimize the control parameters of TiO_(2)/graphene with exposed{001}facets during synthesis,and its enhanced photocatalytic activities were evaluated in the photodegradation of toluene.Experimental results were in good agreement with the predicted results obtained using RSM with a correlation coefficient(R^(2))of 0.9345.When 22.06 mg of graphite oxide(GO)and 2.09 mL of hydrofluoric acid(HF)were added and a hydrothermal time of 28 h was used,a maximum efficiency in the degradation of toluene was achieved.X-ray diffraction(XRD),transmission electron microscopy(TEM),and scanning electron microscopy(SEM)were employed to characterize the obtained hybrid photocatalyst.The electron transferred between Ti and C retarded the combination of electron–hole pairs and hastened the transferring of electrons,which enhanced the photocatalytic activity.展开更多
The adsorptions of a series of alkali metal （AM） atoms, Li, Na, K, Rb and Cs, on a Si（001）-2 × 2 surface at 0.25 monolayer coverage have been investigated systematically by means of density functional theory ...The adsorptions of a series of alkali metal （AM） atoms, Li, Na, K, Rb and Cs, on a Si（001）-2 × 2 surface at 0.25 monolayer coverage have been investigated systematically by means of density functional theory calculations. The effects of the size of AM atoms on the Si（001） surface are focused in the present work by examining the most stable adsorption site, diffusion path, band structure, charge transfer, and the change of work function for different adsorbates. Our results suggest that, when the interactions among AM atoms are neglectable, these AM atoms can be divided into three classes. For Li and Na atoms, they show unique site preferences, and correspond to the strongest and weakest AM-Si interactions, respectively. In particular, the band structure calculation indicates that the nature of Li-Si interaction differs significantly from others. For the adsorptions of other AM atoms with larger size （namely, K, Rb and Cs）, the similarities in the atomic and electronic structures are observed, implying that the atom size has little influence on the adsorption behavior for these large AM atoms on the Si（001） surface.展开更多
The adsorption of metal atoms, Ni, Pd, Pt, Cu, Ag and Au, at low-coordinated edge and corner oxygen sites of MgO (001) surface has been studied theoretically by using density functional method with cluster models embe...The adsorption of metal atoms, Ni, Pd, Pt, Cu, Ag and Au, at low-coordinated edge and corner oxygen sites of MgO (001) surface has been studied theoretically by using density functional method with cluster models embedded in a large array of point charges. For comparison, the interaction of metal atoms with perfect regular oxygen site of MgO (001) surface was also calculated. As regards these metal atoms adsorbed at perfect oxygen sites of MgO (001) surface, Cu, Ag and Au are very weakly bonded to the surface of MgO; Ni, Pd and Pt, on the other hand, exhibit strong interactions with perfect oxygen sites of MgO (001) surface; the large adsorption energy shows that there exist strong bonds formed between these metal atoms with surface oxygen sites. For the metal atoms adsorbed at edge and corner sites, the adsorption energy is much increased, consistent with our previous study of CO and Cl2 adsorption on MgO (001) surface. This illustrates that the low-coordinated sites, especially corner site, are more advantageous positions for those metal atoms adsorbed on MgO (001) surface. The Mulliken population analysis indicates that the electron transferred from MgO to the metal atoms were increased with the decrease of the coordination numbers, which may be one of the reasons for changing catalytic efficiency and selectivity of the metal particles supported by MgO.展开更多
为探索阳离子胺盐和季铵盐在高岭石表面的吸附机理,构建了CH6N+(伯胺阳离子)、C_2H_8N^+(仲胺阳离子)、C3H10N+(叔胺阳离子)及C4H12N+(季铵阳离子)4种不同胺/铵阳离子构型,并采用密度泛函理论对4种阳离子在高岭石(001)面的吸附进行模拟...为探索阳离子胺盐和季铵盐在高岭石表面的吸附机理,构建了CH6N+(伯胺阳离子)、C_2H_8N^+(仲胺阳离子)、C3H10N+(叔胺阳离子)及C4H12N+(季铵阳离子)4种不同胺/铵阳离子构型,并采用密度泛函理论对4种阳离子在高岭石(001)面的吸附进行模拟计算。模拟结果表明,4种阳离子CH6N+,C_2H_8N^+,C3H10N+及C4H12N+在高岭石(001)面都能发生稳定吸附,其较为稳定构型的吸附能分别-125.385,-126.154,-128.654和-109.711 k J/mol;但3种胺阳离子与季铵阳离子的吸附机理不同:胺阳离子在高岭石(001)面的吸附是静电引力和氢键的共同作用,季铵阳离子则只通过静电引力作用与高岭石(001)面发生吸附。静电引力作用是导致不同胺/铵阳离子在高岭石(001)发生吸附的主导作用。展开更多
采用RHEED与STM技术对GaAs(001)-(2×6)表面重构下的表面形貌进行研究,研究发现GaAs(001)-(2×6)重构表面是GaAs(001)-β2(2×4)重构表面经530℃,1.33μPa As BEP退火获得,在(2×6)重构下的GaAs(001)表面形貌已经进入...采用RHEED与STM技术对GaAs(001)-(2×6)表面重构下的表面形貌进行研究,研究发现GaAs(001)-(2×6)重构表面是GaAs(001)-β2(2×4)重构表面经530℃,1.33μPa As BEP退火获得,在(2×6)重构下的GaAs(001)表面形貌已经进入表面存在系列单层岛和坑覆盖的无序平坦状态。为了进一步确定(2×6)重构的原胞结构,采用球棍模型对其原胞结构进行模拟,提出新的As表面覆盖率计算方法、结合STM图片分析对球棍模型进行验证和筛选,首次在实验上证实(2×6)重构原胞中存在2个As Dimers和2个Ga Dimers,并以此重构原胞结构构建理论下的(2×6)重构表面,获得结果与STM图片高度吻合。展开更多
基金supported by the National Natural Science Foundation of China(Nos.21773030,21371034,21503042 and 51574090)Natural Science Foundation Fund of Fujian Province(No.2017J01409)the Education Department of Fujian Province(No.JAT160655)
文摘The CO_2 adsorption on CaO(001) surface at different coverages from 1/9 monolayer(ML) to 1 ML has been investigated using density functional theory calculations. With the analysis of the most stable adsorption structures at different coverages, the mechanism of CaO(001)surface carbonating into CaCO_3 has been explored. At low coverages(≤1/3 ML), CO_2 molecule prefers sitting in parallel pattern on the CaO(001) surface, while the structure of the CaO(001)surface remains unchanged. At medium coverage(4/9 ～ 2/3 ML), the repulsive interactions between oxygen atoms of CO_2 become stronger, and the calcium carbonation structure appears on the CaO(001) surface. At high coverage( ≥ 7/9 ML), the structure of the CaO(001) surface is deeply damaged, and a few CO_2 molecules have penetrated into the surface and bound to the O atom of the second layer(sub-surface), eventually forming the layered structure of CaCO_3.Additionally, herein has discussed the simulation of HREELS and thermodynamical stability of these structures at different coverages.
基金Project supported by the Scientific Research Fund of Hunan Provincial Education Department, China (Grant No. 09B021)
文摘The interaction of Ag atoms with a defective MgO（001） surface is systematically studied based on density functional theory. The Ag clusters are deposited on neutral and charged oxygen vacancies of the MgO（001） surface. The structures of Ag clusters take the shape of simple models of two- or three-dimensional （2D and 3D） metal particles deposited on the MgO surface. When the nucleation of the metal clusters occurs in the Fs （missing neutral O） centre, the interaction with the substrate is considerably stronger than that in the Fs^＋ （missing O-） centre. The results show that the adsorption of Ag atoms on the MgO surface with oxygcn vacancy is stronger than on a clear MgO surface, thereby attracting more Ag atoms to cluster together, and forming atomic islands.
文摘Photocatalytic degradation of gaseous pollutants on Bi-based semiconductors under solar lightirradiation has attracted significant attention.However,their application in gaseous straight-chainalkane purification is still rare.Here,a series of Bi/BiOBr composites were solvothermally synthe-sized and applied in solar-light-driven photocatalytic degradation of gaseous n-hexane.The charac-terization results revealed that both increasing number of functional groups of alcohol solvent(from methanol and ethylene glycol to glycerol)and solvothermal temperature(from 160 and 180to 200℃)facilitated the in-situ formation of metallic Bi nanospheres on BiOBr nanoplates withexposed(110)facets.Meanwhile,chemical bonding between Bi and BiOBr was observed on theseexposed facets that resulted in the formation of surface oxygen vacancy.Furthermore,the synergis-tic effect of optimum surface oxygen vacancy on exposed(110)facets led to a high visible light re-sponse,narrow band gap,great photocurrent,low recombination rate of the charge carriers,andstrong·O2-and h*formation,all of which resulted in the highest removal efficiency of 97.4%within120 min of 15 ppmv of n-hexane on Bi/BiOBr.Our findings efficiently broaden the application ofBi-based photocatalysis technology in the purification of gaseous straight-chain pollutants emittedby the petrochemical industry.
基金supported by the National Natural Science Foundation of China(Nos.21406164,21466035 and 51203111)the National Basic Research Program of China("973"Program,Nos.2012CB720100 and 2014CB239300)
文摘Response surface methodology(RSM)was employed to optimize the control parameters of TiO_(2)/graphene with exposed{001}facets during synthesis,and its enhanced photocatalytic activities were evaluated in the photodegradation of toluene.Experimental results were in good agreement with the predicted results obtained using RSM with a correlation coefficient(R^(2))of 0.9345.When 22.06 mg of graphite oxide(GO)and 2.09 mL of hydrofluoric acid(HF)were added and a hydrothermal time of 28 h was used,a maximum efficiency in the degradation of toluene was achieved.X-ray diffraction(XRD),transmission electron microscopy(TEM),and scanning electron microscopy(SEM)were employed to characterize the obtained hybrid photocatalyst.The electron transferred between Ti and C retarded the combination of electron–hole pairs and hastened the transferring of electrons,which enhanced the photocatalytic activity.
基金supported by the National Natural Science Foundation of China(21203027)Fuzhou University(2012-XQ-11)
文摘The adsorptions of a series of alkali metal （AM） atoms, Li, Na, K, Rb and Cs, on a Si（001）-2 × 2 surface at 0.25 monolayer coverage have been investigated systematically by means of density functional theory calculations. The effects of the size of AM atoms on the Si（001） surface are focused in the present work by examining the most stable adsorption site, diffusion path, band structure, charge transfer, and the change of work function for different adsorbates. Our results suggest that, when the interactions among AM atoms are neglectable, these AM atoms can be divided into three classes. For Li and Na atoms, they show unique site preferences, and correspond to the strongest and weakest AM-Si interactions, respectively. In particular, the band structure calculation indicates that the nature of Li-Si interaction differs significantly from others. For the adsorptions of other AM atoms with larger size （namely, K, Rb and Cs）, the similarities in the atomic and electronic structures are observed, implying that the atom size has little influence on the adsorption behavior for these large AM atoms on the Si（001） surface.
基金This research has been supported by the Foundation of State Key Laboratory of Structural Chemistry the National Natural+3 种基金Science Foundation of China (29973006) and Administration of Science and Technology of Fujian province (2001J018)
文摘The adsorption of metal atoms, Ni, Pd, Pt, Cu, Ag and Au, at low-coordinated edge and corner oxygen sites of MgO (001) surface has been studied theoretically by using density functional method with cluster models embedded in a large array of point charges. For comparison, the interaction of metal atoms with perfect regular oxygen site of MgO (001) surface was also calculated. As regards these metal atoms adsorbed at perfect oxygen sites of MgO (001) surface, Cu, Ag and Au are very weakly bonded to the surface of MgO; Ni, Pd and Pt, on the other hand, exhibit strong interactions with perfect oxygen sites of MgO (001) surface; the large adsorption energy shows that there exist strong bonds formed between these metal atoms with surface oxygen sites. For the metal atoms adsorbed at edge and corner sites, the adsorption energy is much increased, consistent with our previous study of CO and Cl2 adsorption on MgO (001) surface. This illustrates that the low-coordinated sites, especially corner site, are more advantageous positions for those metal atoms adsorbed on MgO (001) surface. The Mulliken population analysis indicates that the electron transferred from MgO to the metal atoms were increased with the decrease of the coordination numbers, which may be one of the reasons for changing catalytic efficiency and selectivity of the metal particles supported by MgO.
基金This work was financially supported by the National Key R&D Program of China(No.2017YFA0205004)the Anhui Initiative in Quantum Information Technologies(AHY090000)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB36020200)the National Natural Science Foundation of China(No.11620101003,No.11904349,and No.21972129).
文摘为探索阳离子胺盐和季铵盐在高岭石表面的吸附机理,构建了CH6N+(伯胺阳离子)、C_2H_8N^+(仲胺阳离子)、C3H10N+(叔胺阳离子)及C4H12N+(季铵阳离子)4种不同胺/铵阳离子构型,并采用密度泛函理论对4种阳离子在高岭石(001)面的吸附进行模拟计算。模拟结果表明,4种阳离子CH6N+,C_2H_8N^+,C3H10N+及C4H12N+在高岭石(001)面都能发生稳定吸附,其较为稳定构型的吸附能分别-125.385,-126.154,-128.654和-109.711 k J/mol;但3种胺阳离子与季铵阳离子的吸附机理不同:胺阳离子在高岭石(001)面的吸附是静电引力和氢键的共同作用,季铵阳离子则只通过静电引力作用与高岭石(001)面发生吸附。静电引力作用是导致不同胺/铵阳离子在高岭石(001)发生吸附的主导作用。
基金The project was supported by the National Natural Science Foundation of China(20903075)Program of Introducing Talents of Discipline to Universities,China(111 Project)(B08040)~~
文摘采用RHEED与STM技术对GaAs(001)-(2×6)表面重构下的表面形貌进行研究,研究发现GaAs(001)-(2×6)重构表面是GaAs(001)-β2(2×4)重构表面经530℃,1.33μPa As BEP退火获得,在(2×6)重构下的GaAs(001)表面形貌已经进入表面存在系列单层岛和坑覆盖的无序平坦状态。为了进一步确定(2×6)重构的原胞结构,采用球棍模型对其原胞结构进行模拟,提出新的As表面覆盖率计算方法、结合STM图片分析对球棍模型进行验证和筛选,首次在实验上证实(2×6)重构原胞中存在2个As Dimers和2个Ga Dimers,并以此重构原胞结构构建理论下的(2×6)重构表面,获得结果与STM图片高度吻合。
基金National Natural Science Foundation of China(51172111,51402159)Shandong Province Higher Educational Science and Technology Program(J14LA17)+1 种基金China Postdoctoral Science Foundation(2015M57073)Qingdao Postdoctoral Application Research Project(2015116)。
