We have applied density functional theory to investigate different types of carbon nanotubes (armchair (4,4)CNT and zig-zag (7,0)CNT) as sensors of some pollutant gas molecules, especially CO, CO2, NO and NO2. We show...We have applied density functional theory to investigate different types of carbon nanotubes (armchair (4,4)CNT and zig-zag (7,0)CNT) as sensors of some pollutant gas molecules, especially CO, CO2, NO and NO2. We show, for the first time, that the adsorption of pollutant gas molecules on carbon nanotubes are improved by introducing the monovacancy defects on the surfaces of (7,0)CNT. The adsorption energies, the optimal adsorption positions and the orientation of these gas molecules on the surfaces of carbon nanotubes are studied. It is found that the most adsorbed pollutant gas is NO molecule on (7,0)CNT.展开更多
We investigate the interactions between two symmetric monovacancy defects in graphene grown on Ru(0001) after silicon intercalation by combining first-principles calculations with scanning tunneling microscopy(STM). F...We investigate the interactions between two symmetric monovacancy defects in graphene grown on Ru(0001) after silicon intercalation by combining first-principles calculations with scanning tunneling microscopy(STM). First-principles calculations based on free-standing graphene show that the interaction is weak and no scattering pattern is observed when the two vacancies are located in the same sublattice of graphene, no matter how close they are, except that they are next to each other. For the two vacancies in different sublattices of graphene, the interaction strongly influences the scattering and new patterns' emerge, which are determined by the distance between two vacancies. Further experiments on silicon intercalated graphene epitaxially grown on Ru(0001) shows that the experiment results are consistent with the simulated STM images based on free-standing graphene, suggesting that a single layer of silicon is good enough to decouple the strong interaction between graphene and the Ru(0001) substrate.展开更多
The monovacancy defect effect on thermal conductivity of bilayer graphene nanoribbons(BGNs)was investigated using non-equilibrium molecular dynamics(NEMD)simulations in this work.Our results demonstrate that the prese...The monovacancy defect effect on thermal conductivity of bilayer graphene nanoribbons(BGNs)was investigated using non-equilibrium molecular dynamics(NEMD)simulations in this work.Our results demonstrate that the presence of monovacancy defect in BGNs reduces their thermal transport properties significantly.The major finding of this work shows that the calculated thermal conductivity reduces approximately linearly with the raise of monovacancy concentration.In contrast to the temperature-dependent thermal conductivity in perfect BGNs,the thermal conductivity of defected BGNs first increases and then decreases with the increasing temperature.In addition,when the difference in the monovacancy density between two layers is larger,the thermal conductivity of BGNs is higher.We also calculated the phonon density of states,phonon relaxation time and participation ratio to provide a deeper understanding of the simulation results.Our investigation confirms that the BGNs-based nano-devices could be applied in thermal management by defect engineering.展开更多
寻找稳定高效的储氢材料是实现氢经济的关键.过渡金属修饰石墨烯储氢材料在理论上被广泛研究,但存在H2解离和金属团聚的问题.本文基于密度泛函理论对Sc,Ti,V修饰单缺陷石墨烯的结构及储氢性能进行计算.结果表明:单缺陷使Sc,Ti,V与石墨...寻找稳定高效的储氢材料是实现氢经济的关键.过渡金属修饰石墨烯储氢材料在理论上被广泛研究,但存在H2解离和金属团聚的问题.本文基于密度泛函理论对Sc,Ti,V修饰单缺陷石墨烯的结构及储氢性能进行计算.结果表明:单缺陷使Sc,Ti,V与石墨烯的结合能提高4—5倍;Sc,Ti,V离子特性增强,可以通过静电相互作用吸附7,3和4个分子形式的氢;平均氢分子吸附能分别为–0.13,–0.20和–0.18 e V,处于室温和中等压力下储氢的最佳能量范围.而Sc,Ti,V修饰的完整石墨烯上第1个氢解离吸附,氢分子吸附能分别为–1.34,–1.34和–1.16 e V.特别重要的是,Sc,V修饰的缺陷石墨烯吸附和脱附氢分子过程中重构能仅为0.00 e V和0.03 e V,对实现快速吸放氢气非常有利.本研究将有利于深入认识3d过渡金属修饰碳材料的储氢机理.展开更多
With Bu4NBr as phase-transfer agent, the monovacant polyoxometalates α-Xn+W11O（12-n）-39（X=P, Si, B, Ga） reacted in acetonitrile with electrophilic C6H5P（S）Cl2 to yield hybrid organic-inorganic species [C6H5P（S...With Bu4NBr as phase-transfer agent, the monovacant polyoxometalates α-Xn+W11O（12-n）-39（X=P, Si, B, Ga） reacted in acetonitrile with electrophilic C6H5P（S）Cl2 to yield hybrid organic-inorganic species [C6H5P（S）]2XW11O（8-n）-39 in satisfactory yield, which have been characterized by elemental analyses, IR and 31P, 183W NMR. The formulation of all tetrabutylammonium salts of [C6H5P（S）]2·XW11（8-n）-O39 are in agreement with the results of elemental analyses, the hybrid anion consists of an α-Xn+W11O（12-n）-39 framework on which are grafted two C6H5P（S） groups through P\O\W bridges. The spectroscopic data show that the [PhP（S）]2XW11O（8-n）-39 compounds possess true Cs symmetry in acetonitrile and remain unsaturated.展开更多
基金Key Research and Development Program of Shandong Province,China (No. 2021ZLGX01)the National Natural Science Foundation of China (No. 52071190)the Shandong Provincial Natural Science Foundation,China (No. ZR2021YQ34)。
文摘We have applied density functional theory to investigate different types of carbon nanotubes (armchair (4,4)CNT and zig-zag (7,0)CNT) as sensors of some pollutant gas molecules, especially CO, CO2, NO and NO2. We show, for the first time, that the adsorption of pollutant gas molecules on carbon nanotubes are improved by introducing the monovacancy defects on the surfaces of (7,0)CNT. The adsorption energies, the optimal adsorption positions and the orientation of these gas molecules on the surfaces of carbon nanotubes are studied. It is found that the most adsorbed pollutant gas is NO molecule on (7,0)CNT.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2016YFA0202300 and 2018YFA0305800)the National Natural Science Foundation of China(Grant Nos.61622116,61474141,61390501,and 11604373)the Pioneer Hundred Talents Program,Chinese Academy of Sciences
文摘We investigate the interactions between two symmetric monovacancy defects in graphene grown on Ru(0001) after silicon intercalation by combining first-principles calculations with scanning tunneling microscopy(STM). First-principles calculations based on free-standing graphene show that the interaction is weak and no scattering pattern is observed when the two vacancies are located in the same sublattice of graphene, no matter how close they are, except that they are next to each other. For the two vacancies in different sublattices of graphene, the interaction strongly influences the scattering and new patterns' emerge, which are determined by the distance between two vacancies. Further experiments on silicon intercalated graphene epitaxially grown on Ru(0001) shows that the experiment results are consistent with the simulated STM images based on free-standing graphene, suggesting that a single layer of silicon is good enough to decouple the strong interaction between graphene and the Ru(0001) substrate.
基金supported by the Basic Science Center Program for Ordered Energy Conversion of the National Natural Science Foundation of China(No.51888103)National Natural Science Foundation of China(No.51606192 and 51706039)the CAS Pioneer Hundred Talents Program.
文摘The monovacancy defect effect on thermal conductivity of bilayer graphene nanoribbons(BGNs)was investigated using non-equilibrium molecular dynamics(NEMD)simulations in this work.Our results demonstrate that the presence of monovacancy defect in BGNs reduces their thermal transport properties significantly.The major finding of this work shows that the calculated thermal conductivity reduces approximately linearly with the raise of monovacancy concentration.In contrast to the temperature-dependent thermal conductivity in perfect BGNs,the thermal conductivity of defected BGNs first increases and then decreases with the increasing temperature.In addition,when the difference in the monovacancy density between two layers is larger,the thermal conductivity of BGNs is higher.We also calculated the phonon density of states,phonon relaxation time and participation ratio to provide a deeper understanding of the simulation results.Our investigation confirms that the BGNs-based nano-devices could be applied in thermal management by defect engineering.
文摘寻找稳定高效的储氢材料是实现氢经济的关键.过渡金属修饰石墨烯储氢材料在理论上被广泛研究,但存在H2解离和金属团聚的问题.本文基于密度泛函理论对Sc,Ti,V修饰单缺陷石墨烯的结构及储氢性能进行计算.结果表明:单缺陷使Sc,Ti,V与石墨烯的结合能提高4—5倍;Sc,Ti,V离子特性增强,可以通过静电相互作用吸附7,3和4个分子形式的氢;平均氢分子吸附能分别为–0.13,–0.20和–0.18 e V,处于室温和中等压力下储氢的最佳能量范围.而Sc,Ti,V修饰的完整石墨烯上第1个氢解离吸附,氢分子吸附能分别为–1.34,–1.34和–1.16 e V.特别重要的是,Sc,V修饰的缺陷石墨烯吸附和脱附氢分子过程中重构能仅为0.00 e V和0.03 e V,对实现快速吸放氢气非常有利.本研究将有利于深入认识3d过渡金属修饰碳材料的储氢机理.
文摘With Bu4NBr as phase-transfer agent, the monovacant polyoxometalates α-Xn+W11O（12-n）-39（X=P, Si, B, Ga） reacted in acetonitrile with electrophilic C6H5P（S）Cl2 to yield hybrid organic-inorganic species [C6H5P（S）]2XW11O（8-n）-39 in satisfactory yield, which have been characterized by elemental analyses, IR and 31P, 183W NMR. The formulation of all tetrabutylammonium salts of [C6H5P（S）]2·XW11（8-n）-O39 are in agreement with the results of elemental analyses, the hybrid anion consists of an α-Xn+W11O（12-n）-39 framework on which are grafted two C6H5P（S） groups through P\O\W bridges. The spectroscopic data show that the [PhP（S）]2XW11O（8-n）-39 compounds possess true Cs symmetry in acetonitrile and remain unsaturated.
