In this study, we employed the density functional theory method to simulate Li-, Na- and K-adsorbed boron α1-sheets(al-BSTs). After optimizing possible structures, we investigated their thermodynamic stabilities, b...In this study, we employed the density functional theory method to simulate Li-, Na- and K-adsorbed boron α1-sheets(al-BSTs). After optimizing possible structures, we investigated their thermodynamic stabilities, barriers for metal atom diffusion on the substrate, and work functions. The computed results indicate that the work function of α1-BST decreases significantly after the adsorption of Li, Na and K. Furthermore, under high hole coverage, these alkali-metal-adsorbed α1-BSTs have lower work functions than the two-dimensional materials of greatest concern and the commonly used electrode materials Ca and Mg. Therefore, the Li-, Na- and K-adsorbed α1-BSTs are potential low-work-function nanomaterials.展开更多
The adsorption of isolated alkali metal atoms (Li, Na, K, Rb, and Cs) on defect-free sur- face of MgO(001) has been systemically investigated with density functional theory using a pseudopotential plane-wave appro...The adsorption of isolated alkali metal atoms (Li, Na, K, Rb, and Cs) on defect-free sur- face of MgO(001) has been systemically investigated with density functional theory using a pseudopotential plane-wave approach. The adsorption energy calculated is about -0.72 eV for the lithium on top of the surface O site and about one third of this value for the other alkali metals. The relatively strong interaction of Li with the surface O can be explained by a more covalent bonding involved, evidenced by results of both the projected density of states and the charge density difference. The bonding mechanism is discussed in detail for all alkali metals.展开更多
A plane wave density functional theory method was used to investigate the adsorption properties of isolated alkali metal atoms, including Li, Na, K, Rb and Cs on-top of the F 0 s defective center of MgO(001) surface...A plane wave density functional theory method was used to investigate the adsorption properties of isolated alkali metal atoms, including Li, Na, K, Rb and Cs on-top of the F 0 s defective center of MgO(001) surface. Among all the alkali metals, the lithium atom binds most strongly with the highest adsorption energy of 0.67 eV and the shortest distance of about 0.257 nm between metal and the surface, the binding energy for the sodium atom comes second, and just half of this value for the other alkali metal atoms. The relatively strong interaction of Li with the F 0 s center can be explained by a more covalent bonding involved, evidenced by results of both the projected density of states and the projected charge density. The bonding mechanism is discussed in detail.展开更多
功函数是金属光阴极的一项重要特性,决定了光电子发射量子效率。金属表面在大气环境中容易受表面吸附污染的影响,从而改变表面功函数,并可能影响光电子发射性能。本工作通过光电子能谱的方法,研究常用做光阴极材料的多晶铜和金表面在大...功函数是金属光阴极的一项重要特性,决定了光电子发射量子效率。金属表面在大气环境中容易受表面吸附污染的影响,从而改变表面功函数,并可能影响光电子发射性能。本工作通过光电子能谱的方法,研究常用做光阴极材料的多晶铜和金表面在大气环境中的吸附污染,及其对表面功函数的影响。根据紫外光电子能谱的测量,发现铜和金金属表面存在吸附污染时功函数相比纯净金属表面分别降低约0.1 e V和0.7 e V。利用X射线光电子能谱分析发现有机分子吸附污染使得金样品的表面功函数降低;而对于铜样品表面,导致功函数降低的因素包括有机分子吸附和表面氧化。本研究对光阴极的应用具有指导意义。展开更多
基金Supported by the National Natural Science Foundation of China(Nos.21173072, 21601054).
文摘In this study, we employed the density functional theory method to simulate Li-, Na- and K-adsorbed boron α1-sheets(al-BSTs). After optimizing possible structures, we investigated their thermodynamic stabilities, barriers for metal atom diffusion on the substrate, and work functions. The computed results indicate that the work function of α1-BST decreases significantly after the adsorption of Li, Na and K. Furthermore, under high hole coverage, these alkali-metal-adsorbed α1-BSTs have lower work functions than the two-dimensional materials of greatest concern and the commonly used electrode materials Ca and Mg. Therefore, the Li-, Na- and K-adsorbed α1-BSTs are potential low-work-function nanomaterials.
文摘The adsorption of isolated alkali metal atoms (Li, Na, K, Rb, and Cs) on defect-free sur- face of MgO(001) has been systemically investigated with density functional theory using a pseudopotential plane-wave approach. The adsorption energy calculated is about -0.72 eV for the lithium on top of the surface O site and about one third of this value for the other alkali metals. The relatively strong interaction of Li with the surface O can be explained by a more covalent bonding involved, evidenced by results of both the projected density of states and the charge density difference. The bonding mechanism is discussed in detail for all alkali metals.
基金supported by the National Natural Science Foundation of China (Grant No.60877017)the Innovation Program of Shanghai Municipal Education Commission (Grant No.08YZ04)
文摘A plane wave density functional theory method was used to investigate the adsorption properties of isolated alkali metal atoms, including Li, Na, K, Rb and Cs on-top of the F 0 s defective center of MgO(001) surface. Among all the alkali metals, the lithium atom binds most strongly with the highest adsorption energy of 0.67 eV and the shortest distance of about 0.257 nm between metal and the surface, the binding energy for the sodium atom comes second, and just half of this value for the other alkali metal atoms. The relatively strong interaction of Li with the F 0 s center can be explained by a more covalent bonding involved, evidenced by results of both the projected density of states and the projected charge density. The bonding mechanism is discussed in detail.
文摘功函数是金属光阴极的一项重要特性,决定了光电子发射量子效率。金属表面在大气环境中容易受表面吸附污染的影响,从而改变表面功函数,并可能影响光电子发射性能。本工作通过光电子能谱的方法,研究常用做光阴极材料的多晶铜和金表面在大气环境中的吸附污染,及其对表面功函数的影响。根据紫外光电子能谱的测量,发现铜和金金属表面存在吸附污染时功函数相比纯净金属表面分别降低约0.1 e V和0.7 e V。利用X射线光电子能谱分析发现有机分子吸附污染使得金样品的表面功函数降低;而对于铜样品表面,导致功函数降低的因素包括有机分子吸附和表面氧化。本研究对光阴极的应用具有指导意义。
基金Supported by Research project of Xi′an Polytechnic University(107020492)National Natural Science Foundation of China(51905405)Natural Science Basic Research Plan in Shannxi Province of China(2019JQ-855)。