Silicon carbide nanotubes（SiCNTs） with special morphology synthesized by supercritical hydrothermal method at 470 C and 8 MPa have been reported in this paper.SiCNTs with special morphology were characterized by tra...Silicon carbide nanotubes（SiCNTs） with special morphology synthesized by supercritical hydrothermal method at 470 C and 8 MPa have been reported in this paper.SiCNTs with special morphology were characterized by transmission electron microscopy（TEM） and high-resolution TEM（HRTEM）.There are two kinds of silicon carbide with special morphology：One is oval SiCNTs with small aspect ratio,the other is bamboo cone-shape structure.SiCNTs have been analyzed by fluorescence spectrometer.The results indicate that the SiCNTs have strong photoluminescence（PL） property.The SiCNTs with oval shape are one kind of intermediate state of growth process of nanotube.The growth mechanism of silicon nanotubes has been proposed based on experiment data.The investigations of growth mechanism of SiCNTs with bamboo structure show that the defect produced in the growth process play the important role in SiCNTs with special structure.展开更多
We study the binding of molecular oxygen to a （5, 0） single walled SiC nanotube, by means of density functional calculations. The center of a hexagon of silicon and carbon atoms in sites on SiCNT surfaces is the mos...We study the binding of molecular oxygen to a （5, 0） single walled SiC nanotube, by means of density functional calculations. The center of a hexagon of silicon and carbon atoms in sites on SiCNT surfaces is the most stable adsorption site for 02 molecule, with a binding energy of -38.22 eV and an average Si-O binding distance of 1.698 A. We have also tested the stability of the 02-adsorbed SiCNT/CNT with ab initio molecular dynamics simulation which have been carried out at room temperature. Furthermore, the adsorption of 02 on the single walled carbon nanotubes has been investigated. Our first-principles calculations predict that the 02 adsorptive capability of silicon carbide nanotubes is much better than that of carbon nanotubes. This might have potential for gas detection and energy storage.展开更多
The density functional theory method is utilized to verify the electronic structures of SiC nanotubes(SiCNTs) and SiC nanoribbons(SiCNRs) one-dimensional(1D) van der Waals homojunctions(vdWh) under an applied axial st...The density functional theory method is utilized to verify the electronic structures of SiC nanotubes(SiCNTs) and SiC nanoribbons(SiCNRs) one-dimensional(1D) van der Waals homojunctions(vdWh) under an applied axial strain and an external electric field. According to the calculated results, the SiCNTs/SiCNRs 1D vdWhs are direct semiconductors with a type-II band alignment and robust electronic structures with different diameters or widths. Furthermore,the SiCNTs/SiCNRs 1D vdWhs are direct semiconductors with a type-I band alignment, respectively, in a range of[-0.3,-0.1] V/A and [0.1, 0.3] V/A and change into metal when the electric field intensity is equal to or higher than0.4 V/A. Interestingly, the SiCNTs/SiCNRs 1D vdWhs have robust electronic structures under axial strain. These findings demonstrate theoretically that the SiCNTs/SiCNRs 1D vdWhs can be employed in nanoelectronics devices.展开更多
The working mechanism of sensors plays an important role in their simulation and design, which is the foundation of their applications. A model of a nanotube NO2 gas sensor system is established based on an （8, 0） s...The working mechanism of sensors plays an important role in their simulation and design, which is the foundation of their applications. A model of a nanotube NO2 gas sensor system is established based on an （8, 0） silicon carbide nanotube （SiCNT） with a NO2 molecule adsorbed. The transport properties of the system are studied with a method combining density functional theory （DFT） with the non-equilibrium Green＇s function （NEGF）. The adsorbed gas molecule plays an important role in the transport properties of the gas sensor, which results in the formation of a transmission peak near the Fermi energy. More importantly, the adsorption leads to different voltage current characteristics of the sensor to that with no adsorption; the difference is large enough to detect the presence of NO2 gas.展开更多
基金Supported by the National Pre-Research Foundation of China(Grant No.51308030201 and Grant No.51323040118)the Foundamental Research Found for central universities(Grant No.72105112)
基金Project supported by the National Natural Science Foundation of China (Grant No.10904106)
文摘Silicon carbide nanotubes（SiCNTs） with special morphology synthesized by supercritical hydrothermal method at 470 C and 8 MPa have been reported in this paper.SiCNTs with special morphology were characterized by transmission electron microscopy（TEM） and high-resolution TEM（HRTEM）.There are two kinds of silicon carbide with special morphology：One is oval SiCNTs with small aspect ratio,the other is bamboo cone-shape structure.SiCNTs have been analyzed by fluorescence spectrometer.The results indicate that the SiCNTs have strong photoluminescence（PL） property.The SiCNTs with oval shape are one kind of intermediate state of growth process of nanotube.The growth mechanism of silicon nanotubes has been proposed based on experiment data.The investigations of growth mechanism of SiCNTs with bamboo structure show that the defect produced in the growth process play the important role in SiCNTs with special structure.
文摘We study the binding of molecular oxygen to a （5, 0） single walled SiC nanotube, by means of density functional calculations. The center of a hexagon of silicon and carbon atoms in sites on SiCNT surfaces is the most stable adsorption site for 02 molecule, with a binding energy of -38.22 eV and an average Si-O binding distance of 1.698 A. We have also tested the stability of the 02-adsorbed SiCNT/CNT with ab initio molecular dynamics simulation which have been carried out at room temperature. Furthermore, the adsorption of 02 on the single walled carbon nanotubes has been investigated. Our first-principles calculations predict that the 02 adsorptive capability of silicon carbide nanotubes is much better than that of carbon nanotubes. This might have potential for gas detection and energy storage.
基金Project supported by the National Natural Science Foundation of China(Grant No.11864011)the Youth Project of Scientific and Technological Research Program of Chongqing Education Commission,China(Grant Nos.KJQN202001207 and KJQN202101204)the Fund from the Educational Commission of Hubei Province,China(Grant No.T201914)。
文摘The density functional theory method is utilized to verify the electronic structures of SiC nanotubes(SiCNTs) and SiC nanoribbons(SiCNRs) one-dimensional(1D) van der Waals homojunctions(vdWh) under an applied axial strain and an external electric field. According to the calculated results, the SiCNTs/SiCNRs 1D vdWhs are direct semiconductors with a type-II band alignment and robust electronic structures with different diameters or widths. Furthermore,the SiCNTs/SiCNRs 1D vdWhs are direct semiconductors with a type-I band alignment, respectively, in a range of[-0.3,-0.1] V/A and [0.1, 0.3] V/A and change into metal when the electric field intensity is equal to or higher than0.4 V/A. Interestingly, the SiCNTs/SiCNRs 1D vdWhs have robust electronic structures under axial strain. These findings demonstrate theoretically that the SiCNTs/SiCNRs 1D vdWhs can be employed in nanoelectronics devices.
基金Project supported by the National Pre-Research Foundation of China (No.51308030201)
文摘The working mechanism of sensors plays an important role in their simulation and design, which is the foundation of their applications. A model of a nanotube NO2 gas sensor system is established based on an （8, 0） silicon carbide nanotube （SiCNT） with a NO2 molecule adsorbed. The transport properties of the system are studied with a method combining density functional theory （DFT） with the non-equilibrium Green＇s function （NEGF）. The adsorbed gas molecule plays an important role in the transport properties of the gas sensor, which results in the formation of a transmission peak near the Fermi energy. More importantly, the adsorption leads to different voltage current characteristics of the sensor to that with no adsorption; the difference is large enough to detect the presence of NO2 gas.
