研究提出一种通过化学键键能差进行能量密度快速估算的方法,和一种利用拉普拉斯键级和分子片段键离解能相结合快速判断笼型结构稳定性的方法。通过穷举法构建了基于Noradamantane的所有富氮骨架及其435种硝基衍生物,应用上述计算方法筛...研究提出一种通过化学键键能差进行能量密度快速估算的方法,和一种利用拉普拉斯键级和分子片段键离解能相结合快速判断笼型结构稳定性的方法。通过穷举法构建了基于Noradamantane的所有富氮骨架及其435种硝基衍生物,应用上述计算方法筛选兼具高能量密度和稳定性的分子结构,并采用量子化学能量计算和过渡态反应势垒计算验证筛选结果的可靠性。计算发现了两种兼顾高能量密度和结构稳定性的硝基化合物,其爆热、爆速、爆压和金属加速能力的理论计算最大值分别达到7.77 k J·g^(-1)、10.1 km·s^(-1)、47 GPa和1.14倍HMX的金属加速能力,且结构分解反应势垒≥96 k J·mol^(-1)。本研究所建立的含能分子能量密度和稳定性快速筛选方法,可为高能稳定的含能分子设计提供参考。展开更多
本文对纯氮氮笼N_(90)(具有D3d对称性)的分子结构和能量在B3LYP/cc-p VDZ水平下进行计算研究。全面地解析了N_(90)分子的结构,并对它进行了Atoms In Molecule(AIM)分析。图形分析和数值分析结果表明,N_(90)分子内存在多个弱相互作用力...本文对纯氮氮笼N_(90)(具有D3d对称性)的分子结构和能量在B3LYP/cc-p VDZ水平下进行计算研究。全面地解析了N_(90)分子的结构,并对它进行了Atoms In Molecule(AIM)分析。图形分析和数值分析结果表明,N_(90)分子内存在多个弱相互作用力。随后本文论述了这种弱作用力与分子构型之间的相互联系,指出了分子内的弱相互作用力是纯氮大分子N_(90)的热力学稳定的一个重要因素。展开更多
锂离子电池具有能量密度高和循环性好等优点,广泛应用于小型移动设备等领域,但尚不能满足需要兼具高容量和高倍率性能的应用要求.以兼具高比表面积、氮含量高且可调、良好石墨化程度、多尺度分级结构(含孔结构)、有微孔通道的寡层笼壁...锂离子电池具有能量密度高和循环性好等优点,广泛应用于小型移动设备等领域,但尚不能满足需要兼具高容量和高倍率性能的应用要求.以兼具高比表面积、氮含量高且可调、良好石墨化程度、多尺度分级结构(含孔结构)、有微孔通道的寡层笼壁结构等特征的氮掺杂碳纳米笼(NCNC)为锂离子电池负极材料,展现出高的比容量、优异的倍率性能和稳定性,譬如:在0.1 A·g-1小电流密度下,NCNC800的循环稳定的充电比容量可以高达约900 m Ah·g-1,显著优于商业石墨;在20.0 A·g-1大电流密度下,循环500圈后的可逆比容量仍能稳定在约135 m Ah·g-1.如此优异的电化学性能可归因于NCNC的结构特征,如高比表面积、良好石墨化程度、独特介观结构和孔结构,这些特征有利于锂离子传输、电解液渗透和电子传导等.这为开发高倍率和高比容量的锂离子电池负极材料提供思路.展开更多
Hierarchical nitrogen-doped carbon nanocages （hNCNC） with large specific surface areas were used as a catalyst support to immobilize Pt nanoparticles by a microwave-assisted polyol method. The Pt/hNCNC catalyst with...Hierarchical nitrogen-doped carbon nanocages （hNCNC） with large specific surface areas were used as a catalyst support to immobilize Pt nanoparticles by a microwave-assisted polyol method. The Pt/hNCNC catalyst with 20 wt% loading has a homogeneous dispersion of Pt nanoparticles with the average size of 3.3 nm, which is smaller than 4.3 and 4.9 nm for the control catalysts with the same loading supported on hierarchical carbon nanocages （hCNC） and commercial Vulcan XC-72, respec- tively. Accordingly, Pt/hNCNC has a larger electrochemical surface area than Pt/hCNC and Pt/XC-72. The Pt/hNCNC catalyst exhibited excellent electrocatalytic activity and stability for methanol oxidation, which was better than the control catalysts. This was attributed to the en- hanced interaction between Pt and hNCNC due to nitrogen participation in the anchoring function. By making use of the unique advantages of the hNCNC support, a heavy Pt loading up to 60 wt% was prepared without serious agglomeration, which gave a high peak-current density per unit mass of catalyst of 95.6 mA/mg for achieving a high power density. These results showed the potential of the Pt/hNCNC catalyst for methanol oxidation and of the new hNCNC support for wide applications.展开更多
The NO2 molecule adsorption on B12N12 nano-cage was investigated using density functional theory calculations in terms of adsorption energy, HOMO/LUMO energy gap （Eg） changes, charge transfer, structural deformation...The NO2 molecule adsorption on B12N12 nano-cage was investigated using density functional theory calculations in terms of adsorption energy, HOMO/LUMO energy gap （Eg） changes, charge transfer, structural deformation, etc. Furthermore, some aspects of stability and properties of B12N12 including calculation of binding electronic and Gibbs free energies, density of states, and molecular electrostatic potential surfaces are investigated. Three possible configurations for NO2 adsorption on the B12N12 nano-cage are energetically found. Interestingly, the results reveals that the Eg of B12N12 cluster is very sensitive to the pres- ence of NO2 molecules as its value reduces from 6.84 eV in free cluster to 3.23 eV in the most stable configuration of NO2/cluster complex. This phenomenon dramatically increases the electrical conductivity of the cluster, suggesting that the B12N12 nano-cluster may be potential sensor for NO2 gaseous molecule detection.展开更多
We have investigated the electron transport properties of a N24B24 molecule coupled to two metallic contacts with a combination of GW approximation and the non-equilibrium Green＇s- function technique. The calculation...We have investigated the electron transport properties of a N24B24 molecule coupled to two metallic contacts with a combination of GW approximation and the non-equilibrium Green＇s- function technique. The calculations indicate that the four and three resonant tunneling peaks are seen for the density of states （DOS） curves in the cases of single and multiple atomic contacts, respectively. The off state and negative differential resistance （NDR） effect are observed in the I-V characteristics of the N24B24 molecule. The NDR behavior is also observed in voltages of about 354.5, 354, 354.6, and 354.3 V for one, four, six, and eight atomic contacts. Also, the I-V characteristics of N24B24 are in off state at low voltages that is independent of the contact types. The current contact types and indicate that N24B24 molecule curves against the gate voltage depend on behaves as a semiconductor.展开更多
文摘研究提出一种通过化学键键能差进行能量密度快速估算的方法,和一种利用拉普拉斯键级和分子片段键离解能相结合快速判断笼型结构稳定性的方法。通过穷举法构建了基于Noradamantane的所有富氮骨架及其435种硝基衍生物,应用上述计算方法筛选兼具高能量密度和稳定性的分子结构,并采用量子化学能量计算和过渡态反应势垒计算验证筛选结果的可靠性。计算发现了两种兼顾高能量密度和结构稳定性的硝基化合物,其爆热、爆速、爆压和金属加速能力的理论计算最大值分别达到7.77 k J·g^(-1)、10.1 km·s^(-1)、47 GPa和1.14倍HMX的金属加速能力,且结构分解反应势垒≥96 k J·mol^(-1)。本研究所建立的含能分子能量密度和稳定性快速筛选方法,可为高能稳定的含能分子设计提供参考。
文摘本文对纯氮氮笼N_(90)(具有D3d对称性)的分子结构和能量在B3LYP/cc-p VDZ水平下进行计算研究。全面地解析了N_(90)分子的结构,并对它进行了Atoms In Molecule(AIM)分析。图形分析和数值分析结果表明,N_(90)分子内存在多个弱相互作用力。随后本文论述了这种弱作用力与分子构型之间的相互联系,指出了分子内的弱相互作用力是纯氮大分子N_(90)的热力学稳定的一个重要因素。
文摘锂离子电池具有能量密度高和循环性好等优点,广泛应用于小型移动设备等领域,但尚不能满足需要兼具高容量和高倍率性能的应用要求.以兼具高比表面积、氮含量高且可调、良好石墨化程度、多尺度分级结构(含孔结构)、有微孔通道的寡层笼壁结构等特征的氮掺杂碳纳米笼(NCNC)为锂离子电池负极材料,展现出高的比容量、优异的倍率性能和稳定性,譬如:在0.1 A·g-1小电流密度下,NCNC800的循环稳定的充电比容量可以高达约900 m Ah·g-1,显著优于商业石墨;在20.0 A·g-1大电流密度下,循环500圈后的可逆比容量仍能稳定在约135 m Ah·g-1.如此优异的电化学性能可归因于NCNC的结构特征,如高比表面积、良好石墨化程度、独特介观结构和孔结构,这些特征有利于锂离子传输、电解液渗透和电子传导等.这为开发高倍率和高比容量的锂离子电池负极材料提供思路.
基金supported by the National Natural Science Foundation of China(21473089,51232003,21373108,51571110,21573107)the Nation-al Basic Research Program of China(973 Program,2013CB932902)+2 种基金Suzhou Science and Technology Projects(ZXG2013025)Changzhou Science and Technology Projects(CE20130032)supported by a Project Funded by the Technology Support Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Hierarchical nitrogen-doped carbon nanocages （hNCNC） with large specific surface areas were used as a catalyst support to immobilize Pt nanoparticles by a microwave-assisted polyol method. The Pt/hNCNC catalyst with 20 wt% loading has a homogeneous dispersion of Pt nanoparticles with the average size of 3.3 nm, which is smaller than 4.3 and 4.9 nm for the control catalysts with the same loading supported on hierarchical carbon nanocages （hCNC） and commercial Vulcan XC-72, respec- tively. Accordingly, Pt/hNCNC has a larger electrochemical surface area than Pt/hCNC and Pt/XC-72. The Pt/hNCNC catalyst exhibited excellent electrocatalytic activity and stability for methanol oxidation, which was better than the control catalysts. This was attributed to the en- hanced interaction between Pt and hNCNC due to nitrogen participation in the anchoring function. By making use of the unique advantages of the hNCNC support, a heavy Pt loading up to 60 wt% was prepared without serious agglomeration, which gave a high peak-current density per unit mass of catalyst of 95.6 mA/mg for achieving a high power density. These results showed the potential of the Pt/hNCNC catalyst for methanol oxidation and of the new hNCNC support for wide applications.
文摘The NO2 molecule adsorption on B12N12 nano-cage was investigated using density functional theory calculations in terms of adsorption energy, HOMO/LUMO energy gap （Eg） changes, charge transfer, structural deformation, etc. Furthermore, some aspects of stability and properties of B12N12 including calculation of binding electronic and Gibbs free energies, density of states, and molecular electrostatic potential surfaces are investigated. Three possible configurations for NO2 adsorption on the B12N12 nano-cage are energetically found. Interestingly, the results reveals that the Eg of B12N12 cluster is very sensitive to the pres- ence of NO2 molecules as its value reduces from 6.84 eV in free cluster to 3.23 eV in the most stable configuration of NO2/cluster complex. This phenomenon dramatically increases the electrical conductivity of the cluster, suggesting that the B12N12 nano-cluster may be potential sensor for NO2 gaseous molecule detection.
文摘We have investigated the electron transport properties of a N24B24 molecule coupled to two metallic contacts with a combination of GW approximation and the non-equilibrium Green＇s- function technique. The calculations indicate that the four and three resonant tunneling peaks are seen for the density of states （DOS） curves in the cases of single and multiple atomic contacts, respectively. The off state and negative differential resistance （NDR） effect are observed in the I-V characteristics of the N24B24 molecule. The NDR behavior is also observed in voltages of about 354.5, 354, 354.6, and 354.3 V for one, four, six, and eight atomic contacts. Also, the I-V characteristics of N24B24 are in off state at low voltages that is independent of the contact types. The current contact types and indicate that N24B24 molecule curves against the gate voltage depend on behaves as a semiconductor.
