Thermal conduetances between Cu and graphene covered carbon nanotubes （gCNTs） are calculated by molecular dynamics simulations. The results show that the thermal conductance is about ten times larger than that of Cu...Thermal conduetances between Cu and graphene covered carbon nanotubes （gCNTs） are calculated by molecular dynamics simulations. The results show that the thermal conductance is about ten times larger than that of Cu- CNT interface. The enhanced thermal conductance is due to the larger contact area introduced by the graphene layer and the stronger thermal transfer ability of the Cu-gCNT interface. From the linear increasing thermal conductance with the increasing total contact area, an effective contact area of such an interface can be defined.展开更多
Mg-based alloys are regarded as highly promising materials for hydrogen storage.Despite significant improvements of the properties for Mg-based alloys,challenges such as slow hydrogen absorption/desorption kinetics an...Mg-based alloys are regarded as highly promising materials for hydrogen storage.Despite significant improvements of the properties for Mg-based alloys,challenges such as slow hydrogen absorption/desorption kinetics and high thermodynamic stability continue to limit their practical application.In this study,to assess hydrogen storage alloys with enhanced properties,incorporating both internal microstructure modulation through the preparation of amorphous/nanocrystalline structures and surface property enhancement with the addition of Cu and carbon nanotubes(CNTs),the kinetic properties of activation and hydrogenation,thermodynamic properties,and dehydrogenation kinetics are tested.The results reveal a complementary interaction between the added Cu and CNTs,contributing to the superior hydrogen storage performance observed in sample 7A-2Cu-1CNTs with an amorphous/nanocrystalline structure compared to the other experimental samples.Additionally,the samples are fully activated after the initial hydrogen absorption and desorption cycle,demonstrating outstanding hydrogenation kinetics under both high and low temperature experimental conditions.Particularly noteworthy is that the hydrogen absorption exceeds 1.8 wt.% within one hour at 333 K.Furthermore,the activation energy for dehydrogenation is decreased to 64.71 kJ·mol^(–1).This research may offer novel insights for the design of new-type Mg-based hydrogen storage alloys,which possess milder conditions for hydrogen absorption and desorption.展开更多
The structural,energetic and electronic properties of chiral(n,m)(3≤n≤6,n/2≤m≤n)single-wall copper nanotubes(CuNTs)have been investigated by using projector-augmented wave method based on density-functional theory...The structural,energetic and electronic properties of chiral(n,m)(3≤n≤6,n/2≤m≤n)single-wall copper nanotubes(CuNTs)have been investigated by using projector-augmented wave method based on density-functional theory.The(4,3)CuNT is energetically stable and should be observed experimentally in both free-standing and tip-suspended conditions,whereas the(5,5)and(6,4)CuNTs should be observed in free-standing and tip-suspended conditions,respectively.The number of conductance channels in the CuNTs does not always correspond to the number of atomic strands comprising the nanotube.Charge density contours show that there is an enhanced interatomic interaction in CuNTs compared with Cu bulk.Current transporting states display different periods and chirality,the combined effects of which lead to weaker chiral currents on CuNTs.展开更多
基金Supported by the National National Science Foundation of China under Grant No 61131004the Fundamental Research Funds for the Central Universities under Grant No DUT14LAB11
文摘Thermal conduetances between Cu and graphene covered carbon nanotubes （gCNTs） are calculated by molecular dynamics simulations. The results show that the thermal conductance is about ten times larger than that of Cu- CNT interface. The enhanced thermal conductance is due to the larger contact area introduced by the graphene layer and the stronger thermal transfer ability of the Cu-gCNT interface. From the linear increasing thermal conductance with the increasing total contact area, an effective contact area of such an interface can be defined.
基金funded by the National Key R&D Program of China(No.2021YFB4000604)the National Natural Science Foundations of China(No.52261041)+3 种基金Key R&D projects of Jilin Provincial Science and Technology Development Plan(No.20230201125GX)Youth Growth Science and Technology Program of Jilin Province(No.20220508001RC)Youth Innovation Promotion Association CAS(No.2022225)Independent Research Project of the State Key Laboratory of Rare Earth Resources Utilization,and Changchun Institute of Applied Chemistry,Chinese Academy of Sciences(No.110000RL86).
文摘Mg-based alloys are regarded as highly promising materials for hydrogen storage.Despite significant improvements of the properties for Mg-based alloys,challenges such as slow hydrogen absorption/desorption kinetics and high thermodynamic stability continue to limit their practical application.In this study,to assess hydrogen storage alloys with enhanced properties,incorporating both internal microstructure modulation through the preparation of amorphous/nanocrystalline structures and surface property enhancement with the addition of Cu and carbon nanotubes(CNTs),the kinetic properties of activation and hydrogenation,thermodynamic properties,and dehydrogenation kinetics are tested.The results reveal a complementary interaction between the added Cu and CNTs,contributing to the superior hydrogen storage performance observed in sample 7A-2Cu-1CNTs with an amorphous/nanocrystalline structure compared to the other experimental samples.Additionally,the samples are fully activated after the initial hydrogen absorption and desorption cycle,demonstrating outstanding hydrogenation kinetics under both high and low temperature experimental conditions.Particularly noteworthy is that the hydrogen absorption exceeds 1.8 wt.% within one hour at 333 K.Furthermore,the activation energy for dehydrogenation is decreased to 64.71 kJ·mol^(–1).This research may offer novel insights for the design of new-type Mg-based hydrogen storage alloys,which possess milder conditions for hydrogen absorption and desorption.
基金supported by the State Key Development for Basic Research of China(Grant No.2010CB631002) the National Natural Science Foundation of China(Grant Nos.51071098,11104175 and 11214216)
文摘The structural,energetic and electronic properties of chiral(n,m)(3≤n≤6,n/2≤m≤n)single-wall copper nanotubes(CuNTs)have been investigated by using projector-augmented wave method based on density-functional theory.The(4,3)CuNT is energetically stable and should be observed experimentally in both free-standing and tip-suspended conditions,whereas the(5,5)and(6,4)CuNTs should be observed in free-standing and tip-suspended conditions,respectively.The number of conductance channels in the CuNTs does not always correspond to the number of atomic strands comprising the nanotube.Charge density contours show that there is an enhanced interatomic interaction in CuNTs compared with Cu bulk.Current transporting states display different periods and chirality,the combined effects of which lead to weaker chiral currents on CuNTs.
