致密油在储层多孔介质中的吸附研究多以定量的实验研究为主,定性的机理研究较少。以正己烷为对象,从原子分子层面定性研究其在碳酸钙表面的吸附能力,为解释致密油在储层岩石基质上的吸附性提供了有力依据。采用基于密度泛函理论的第一...致密油在储层多孔介质中的吸附研究多以定量的实验研究为主,定性的机理研究较少。以正己烷为对象,从原子分子层面定性研究其在碳酸钙表面的吸附能力,为解释致密油在储层岩石基质上的吸附性提供了有力依据。采用基于密度泛函理论的第一性原理方法,计算了C_6H_(14)分子在CaCO_3(100)面的吸附能,对比分析了吸附前后的物理结构和电子态密度。结果表明:C_6H_(14)分子在B11位吸附最稳定,吸附能为-0.782 4 eV,吸附后键长键角变化率均小于1%,是一种弱化学吸附。不同吸附位的能量差值很小,仅为0.017 8 e V,C_6H_(14)分子容易在CaCO_3表面发生稳定流动。吸附后,C_6H_(14)分子的电子态密度向低能量区域整体偏移约3.1 e V,而CaCO_3(100)面的电子态密度曲线基本重合,吸附作用对C_6H_(14)分子的电子结构影响显著,对CaCO_3(100)面电子结构影响甚微。展开更多
Pyrite （FeS2） bulk and （100） surface properties and the oxygen adsorption on the surface were studied by using density functional theory methods. The results show that in the formation of FeS2 （100） surface, the...Pyrite （FeS2） bulk and （100） surface properties and the oxygen adsorption on the surface were studied by using density functional theory methods. The results show that in the formation of FeS2 （100） surface, there exists a process of electron transfer from Fe dangling bond to S dangling bond. In this situation, surface Fe and S atoms have more ionic properties. Both Fe2+ and S2- have high electrochemistry reduction activity, which is the base for oxygen adsorption. From the viewpoint of adsorption energy, the parallel form oxygen adsorption is in preference. The result also shows that the state of oxygen absorbed on FeS2 surface acts as peroxides rather than O2.展开更多
The interaction of atomic oxygen with the clean Cu（100） surface has been studied by means of cluster and periodic slab models density functional theory in the present paper. The Cu（4,9,4） cluster and a three-layer...The interaction of atomic oxygen with the clean Cu（100） surface has been studied by means of cluster and periodic slab models density functional theory in the present paper. The Cu（4,9,4） cluster and a three-layer slab with c（2×2） structure are used to model the perfect Cn（100） surface. Three possible adsorption sites, top, bridge and hollow site, were considered in the calculations. The predicted results show that the hollow site is the prefer site for atomic oxygen adsorbed on Cu（100） surface energetically. This is in good agreement with the experiment. The calculated binding energies are respective 2.014, 3.154 and 3.942 eV for top, bridge and hollow sites at mPW1PW91/LanL2dz level for the cluster model. The geometry of Cu（100） surface has also been optimized theoretically with various density functional rnethods and the results show that the prediction from the B3PW91/LanL2dz and mPWlPW91/LanL2dz reproduce the experimental observation. The frontier molecular orbitals and partial density of states analysis show that the electron transfer from the d orbital of substrate to the p orbital of the surface oxygen atom.展开更多
Magnetically recyclable porous sodium dodecyl sulfate(SDS)/Fe2O3 hybrids,which combine the porous structure of Fe2O3 and hydrophobicity of SDS,have been successfully synthesized for the first time.Porous Fe2O3 has bee...Magnetically recyclable porous sodium dodecyl sulfate(SDS)/Fe2O3 hybrids,which combine the porous structure of Fe2O3 and hydrophobicity of SDS,have been successfully synthesized for the first time.Porous Fe2O3 has been first pyrolyzed from MIL-100(Fe)using a simple two-step calcination route.Then,the obtained porous Fe2O3 nanoparticles have been self-assembled with SDS molecules and yielded hydrophobic SDS/Fe2O3 hybrids.The porous SDS/Fe2O3 hybrids have been demonstrated to be highly efficient for the denitrification of pyridine under visible light irradiation.The pyridine removal ratio has reached values as high as 100%after irradiation for 240 min.Combining the results of a series of experimental measurements,it was concluded that the superior photocatalytic performance of SDS/Fe2O3 hybrids could be attributed to(i)the fast electron transport owing to the unique porous structure of Fe2O3,(ii)the superior visible light absorption of Fe2O3 nanoparticles,and(iii)the“bridge molecule”role of SDS efficiently improving the separation and transfer across the interfacial domain of SDS/Fe2O3 of photogenerated electron-hole pairs.More significantly,after the catalytic reaction,the SDS/Fe2O3 hybrids could be easily recovered using magnets and reused during subsequent cycles,which indicated their stability and recyclability.展开更多
Cloud point （CP） determinations of 4-（1,1,3,3-tetramethylbutyl）phenyl-polyethylene glycol （TX-100 （nonionic surfactant）） was carried out in aqueous as well as in the attendance of drug （ceftriaxone sodium tri...Cloud point （CP） determinations of 4-（1,1,3,3-tetramethylbutyl）phenyl-polyethylene glycol （TX-100 （nonionic surfactant）） was carried out in aqueous as well as in the attendance of drug （ceftriaxone sodium trihydrate （CFT））/（CFT ＋ different inorganic salts） and discussed thoroughly. Nonionic surfactants are employed exten- sively in different formulations. In aqueous solution, the values of CP of TX-100 are obtained to increase by means of enhancing of their concentration in the solution. The CP values of TX-100 solutions were found to de- crease in the presence of drug and their values decrease more with rising concentrations of the drug. The values of CP of CFT and TX-100 mixtures were found to further decrease in the attendance of inorganic salts in compar- ison to their absence. The effect of different sodium salts in decreasing CP values of TX-100 was achieved in the following order： NaCO3 〉 Na2SO4 〉 NaCl. However, in the case of potassium and ammonium salts, the decreasing order obtained is K2SO4 〉 KCO3 〉 KCI and （NH4）2SO4 〉 Na2CO3 〉 NH4Cl respectively. Various thermodynamic pa- rameters for example standard free energy （△G c）, standard enthalpy （△H c） as well as standard entropy （△S c） changes of phase separation were also evaluated and discussed in detail on the basis of their behavior.展开更多
The molecular-level identification of a chiral recognition process of phthalocyanine （Pc） was studied on a Cu（100） surface by scanning tunneling microscopy （STM）. STM revealed that a chiral Pc molecule forms a s...The molecular-level identification of a chiral recognition process of phthalocyanine （Pc） was studied on a Cu（100） surface by scanning tunneling microscopy （STM）. STM revealed that a chiral Pc molecule forms a series of metastable dimer configurations with other Pc molecules. Eventually, the Pc molecule recognizes another Pc molecule with the same chirality to form a stable dimer configuration. Homochiral dimers were found on the Cu surface, demonstrating the chiral specificity of Pc dimerization. The mechanism for this chiral recognition process is identified, disclosing the critical role of the particular adsorption geometry of the chiral dimers on the Cu surface.展开更多
文摘致密油在储层多孔介质中的吸附研究多以定量的实验研究为主,定性的机理研究较少。以正己烷为对象,从原子分子层面定性研究其在碳酸钙表面的吸附能力,为解释致密油在储层岩石基质上的吸附性提供了有力依据。采用基于密度泛函理论的第一性原理方法,计算了C_6H_(14)分子在CaCO_3(100)面的吸附能,对比分析了吸附前后的物理结构和电子态密度。结果表明:C_6H_(14)分子在B11位吸附最稳定,吸附能为-0.782 4 eV,吸附后键长键角变化率均小于1%,是一种弱化学吸附。不同吸附位的能量差值很小,仅为0.017 8 e V,C_6H_(14)分子容易在CaCO_3表面发生稳定流动。吸附后,C_6H_(14)分子的电子态密度向低能量区域整体偏移约3.1 e V,而CaCO_3(100)面的电子态密度曲线基本重合,吸附作用对C_6H_(14)分子的电子结构影响显著,对CaCO_3(100)面电子结构影响甚微。
文摘Pyrite （FeS2） bulk and （100） surface properties and the oxygen adsorption on the surface were studied by using density functional theory methods. The results show that in the formation of FeS2 （100） surface, there exists a process of electron transfer from Fe dangling bond to S dangling bond. In this situation, surface Fe and S atoms have more ionic properties. Both Fe2+ and S2- have high electrochemistry reduction activity, which is the base for oxygen adsorption. From the viewpoint of adsorption energy, the parallel form oxygen adsorption is in preference. The result also shows that the state of oxygen absorbed on FeS2 surface acts as peroxides rather than O2.
基金This work was supported by National Natural Science Foundation of China （NSFC No. 20273013） and Pujian Provincial Department of Education （No. JA03020）
文摘The interaction of atomic oxygen with the clean Cu（100） surface has been studied by means of cluster and periodic slab models density functional theory in the present paper. The Cu（4,9,4） cluster and a three-layer slab with c（2×2） structure are used to model the perfect Cn（100） surface. Three possible adsorption sites, top, bridge and hollow site, were considered in the calculations. The predicted results show that the hollow site is the prefer site for atomic oxygen adsorbed on Cu（100） surface energetically. This is in good agreement with the experiment. The calculated binding energies are respective 2.014, 3.154 and 3.942 eV for top, bridge and hollow sites at mPW1PW91/LanL2dz level for the cluster model. The geometry of Cu（100） surface has also been optimized theoretically with various density functional rnethods and the results show that the prediction from the B3PW91/LanL2dz and mPWlPW91/LanL2dz reproduce the experimental observation. The frontier molecular orbitals and partial density of states analysis show that the electron transfer from the d orbital of substrate to the p orbital of the surface oxygen atom.
基金supported by the National Natural Science Foundation of China(21603112,21806085)Natural Science Foundation of Fujian Province(2016J02692,2019J01837)+1 种基金Natural Science Foundation of Ningde Normal University(2018T03,2018Z02)the Program of Innovative Research Team in Science and Technology in Fujian Province University(IRTSTFJ)~~
文摘Magnetically recyclable porous sodium dodecyl sulfate(SDS)/Fe2O3 hybrids,which combine the porous structure of Fe2O3 and hydrophobicity of SDS,have been successfully synthesized for the first time.Porous Fe2O3 has been first pyrolyzed from MIL-100(Fe)using a simple two-step calcination route.Then,the obtained porous Fe2O3 nanoparticles have been self-assembled with SDS molecules and yielded hydrophobic SDS/Fe2O3 hybrids.The porous SDS/Fe2O3 hybrids have been demonstrated to be highly efficient for the denitrification of pyridine under visible light irradiation.The pyridine removal ratio has reached values as high as 100%after irradiation for 240 min.Combining the results of a series of experimental measurements,it was concluded that the superior photocatalytic performance of SDS/Fe2O3 hybrids could be attributed to(i)the fast electron transport owing to the unique porous structure of Fe2O3,(ii)the superior visible light absorption of Fe2O3 nanoparticles,and(iii)the“bridge molecule”role of SDS efficiently improving the separation and transfer across the interfacial domain of SDS/Fe2O3 of photogenerated electron-hole pairs.More significantly,after the catalytic reaction,the SDS/Fe2O3 hybrids could be easily recovered using magnets and reused during subsequent cycles,which indicated their stability and recyclability.
基金Jahangirnagar University,Savar,Dhaka,Bangladesh for providing financial support to carry out the research work
文摘Cloud point （CP） determinations of 4-（1,1,3,3-tetramethylbutyl）phenyl-polyethylene glycol （TX-100 （nonionic surfactant）） was carried out in aqueous as well as in the attendance of drug （ceftriaxone sodium trihydrate （CFT））/（CFT ＋ different inorganic salts） and discussed thoroughly. Nonionic surfactants are employed exten- sively in different formulations. In aqueous solution, the values of CP of TX-100 are obtained to increase by means of enhancing of their concentration in the solution. The CP values of TX-100 solutions were found to de- crease in the presence of drug and their values decrease more with rising concentrations of the drug. The values of CP of CFT and TX-100 mixtures were found to further decrease in the attendance of inorganic salts in compar- ison to their absence. The effect of different sodium salts in decreasing CP values of TX-100 was achieved in the following order： NaCO3 〉 Na2SO4 〉 NaCl. However, in the case of potassium and ammonium salts, the decreasing order obtained is K2SO4 〉 KCO3 〉 KCI and （NH4）2SO4 〉 Na2CO3 〉 NH4Cl respectively. Various thermodynamic pa- rameters for example standard free energy （△G c）, standard enthalpy （△H c） as well as standard entropy （△S c） changes of phase separation were also evaluated and discussed in detail on the basis of their behavior.
基金Acknowledgements This work was supported by the National Basic Research Program of China （No. 2013CB934200） and the National Natural Science Foundation of China （Nos. 10979015 and 50976048）. L. W. acknowledges the financial support from the Program for New Century Excellent Talents in University, Ministry of Education of the People＇s Republic of China （No. NECT-11-1003） and Jiangxi Provincial ＂Ganpo Talents 555 Projects＂. M. D. D. acknowledges financial support from the Danish National Research Foundation, the Carlsberg Foundation, and the Villum Foundation.
文摘The molecular-level identification of a chiral recognition process of phthalocyanine （Pc） was studied on a Cu（100） surface by scanning tunneling microscopy （STM）. STM revealed that a chiral Pc molecule forms a series of metastable dimer configurations with other Pc molecules. Eventually, the Pc molecule recognizes another Pc molecule with the same chirality to form a stable dimer configuration. Homochiral dimers were found on the Cu surface, demonstrating the chiral specificity of Pc dimerization. The mechanism for this chiral recognition process is identified, disclosing the critical role of the particular adsorption geometry of the chiral dimers on the Cu surface.
