Single-wall carbon nanotubes （SWNTs） with high surface area were synthesized over nanoporous Co-Mo/MgO by a chemical vapor deposition （CVD） method. The SWNTs were used as catalyst support for selective hydrogenati...Single-wall carbon nanotubes （SWNTs） with high surface area were synthesized over nanoporous Co-Mo/MgO by a chemical vapor deposition （CVD） method. The SWNTs were used as catalyst support for selective hydrogenation of syngas to hydrocarbons. Here an extensive study of Fischer-Tropsch synthesis （FTS） on CNT-supported cobalt catalysts with different amounts of cobalt loading up to 40 wt% is reported. The catalysts were characterized by different methods including N2 adsorption-desorption, X-ray diffraction, hydrogen chemisorption, inductively coupled plasma （ICP） and temperature-programmed reduction. Enhancement of the reducibility of Co3O4 to CoO, CoO to Co° and small cobalt oxide particles, dispersion of the cobalt, and activity and selectivity of FTS were investigated and compared with a conventional support. The CNT supported catalysts achieve a high dispersion and high loading of the active metal, cobalt in particular, so that the bulk formation of cobalt metal, which tends to occur in conventional support, can be avoided. The results showed that the specific activity of CNT supported catalysts increase significantly （there is a two fold increase in CO Conversion per gram of the active metal） with respect to the conventional supported catalyst.展开更多
This paper reveals, by analyses of nitrogen cryo-adsorption isotherm, the energetic and structural heterogeneity of single-walled carbon nanotubes (SWNTs) which has a high hydrogen storage capacity. It was found that ...This paper reveals, by analyses of nitrogen cryo-adsorption isotherm, the energetic and structural heterogeneity of single-walled carbon nanotubes (SWNTs) which has a high hydrogen storage capacity. It was found that SWNTs had manifold pore structures and distributed surface energy. By comparison of the pore structures and energy distributions of SWNTs before and after hydrogen adsorption, it is preliminarily indicated that hydrogen adsorption occurred in micropores and mesopores with smaller diameter, and that the pores of different diameters determined different hydrogen adsorption processes and underwent different structure changes during hydrogen adsorption.展开更多
Helical amylose/SWNTs complexes (A/S-C) of various sizes, a single nanotube wrapped by amylose in particular, were demonstrated. The formation process of the helical A/S-C was further explained by a novel hierarchical...Helical amylose/SWNTs complexes (A/S-C) of various sizes, a single nanotube wrapped by amylose in particular, were demonstrated. The formation process of the helical A/S-C was further explained by a novel hierarchical self-assembly model, including the wrapping of amylose chains around SWNT and the hierarchical self-assembly of wrapped-SWNTs into the superstructural A/S-C. Besides the hydrophobic interaction, the hydrogen bonding also plays a certain role in the self-assembly process.展开更多
We employed molecular dynamics simulations to investigate the directed transport of a double-stranded oligonucleotide(ds DNA)through a single-walled carbon nanotube(SWNT)powered by external mechanical vibrations.It is...We employed molecular dynamics simulations to investigate the directed transport of a double-stranded oligonucleotide(ds DNA)through a single-walled carbon nanotube(SWNT)powered by external mechanical vibrations.It is thermodynamically favorable for ds DNA to adsorb inside the SWNT,and its transport through the nanotube is challenging due to the high energy barrier.However,we demonstrate that mechanical vibrations at specific frequencies can effectively drive the ds DNA through the nanotube based on a ratchet effect.The system is driven away from thermal equilibrium,and the spatial inversion symmetry is broken by mechanical vibrations.This study provides valuable insights into the mechanisms of mechanically activated DNA transport and highlights the potential of using SWNTs as nanoscale conduits for ds DNA delivery in nanobiotechnology and biomedicine.展开更多
MoS2 nanotube coated SWNT (Single wall carbon nanotube) bundles have been successfully prepared by adsorbing (NH4)2MoS4 onto SWNT bundles and subsequent heat treatment under H2 at 900 ℃ in a tube furnace. The morphol...MoS2 nanotube coated SWNT (Single wall carbon nanotube) bundles have been successfully prepared by adsorbing (NH4)2MoS4 onto SWNT bundles and subsequent heat treatment under H2 at 900 ℃ in a tube furnace. The morphologies, structure and composition of the as-prepared sample were investigated by XRD, SEM, HRTEM coupled with EDS. The formation mechanism has also been preliminarily discussed.展开更多
文摘Single-wall carbon nanotubes （SWNTs） with high surface area were synthesized over nanoporous Co-Mo/MgO by a chemical vapor deposition （CVD） method. The SWNTs were used as catalyst support for selective hydrogenation of syngas to hydrocarbons. Here an extensive study of Fischer-Tropsch synthesis （FTS） on CNT-supported cobalt catalysts with different amounts of cobalt loading up to 40 wt% is reported. The catalysts were characterized by different methods including N2 adsorption-desorption, X-ray diffraction, hydrogen chemisorption, inductively coupled plasma （ICP） and temperature-programmed reduction. Enhancement of the reducibility of Co3O4 to CoO, CoO to Co° and small cobalt oxide particles, dispersion of the cobalt, and activity and selectivity of FTS were investigated and compared with a conventional support. The CNT supported catalysts achieve a high dispersion and high loading of the active metal, cobalt in particular, so that the bulk formation of cobalt metal, which tends to occur in conventional support, can be avoided. The results showed that the specific activity of CNT supported catalysts increase significantly （there is a two fold increase in CO Conversion per gram of the active metal） with respect to the conventional supported catalyst.
基金This work was supported by the Special Fund for Major Basic Research Projects (G2000026403)the National Natural Science Foundation of China (Grant Nos. 50032020 and 50025204)Yang Quanhong is also indebted to China Postdoctoral Science Foundation
文摘This paper reveals, by analyses of nitrogen cryo-adsorption isotherm, the energetic and structural heterogeneity of single-walled carbon nanotubes (SWNTs) which has a high hydrogen storage capacity. It was found that SWNTs had manifold pore structures and distributed surface energy. By comparison of the pore structures and energy distributions of SWNTs before and after hydrogen adsorption, it is preliminarily indicated that hydrogen adsorption occurred in micropores and mesopores with smaller diameter, and that the pores of different diameters determined different hydrogen adsorption processes and underwent different structure changes during hydrogen adsorption.
基金Supported by the National Natural Science Foundation of China (Grant No. 60577049)Shanghai Municipal Science and Technology Commission (Grant Nos. 034319224 and 0652nm017)
文摘Helical amylose/SWNTs complexes (A/S-C) of various sizes, a single nanotube wrapped by amylose in particular, were demonstrated. The formation process of the helical A/S-C was further explained by a novel hierarchical self-assembly model, including the wrapping of amylose chains around SWNT and the hierarchical self-assembly of wrapped-SWNTs into the superstructural A/S-C. Besides the hydrophobic interaction, the hydrogen bonding also plays a certain role in the self-assembly process.
基金supported by the National Natural Science Foundation of China(Grant No.11875237)。
文摘We employed molecular dynamics simulations to investigate the directed transport of a double-stranded oligonucleotide(ds DNA)through a single-walled carbon nanotube(SWNT)powered by external mechanical vibrations.It is thermodynamically favorable for ds DNA to adsorb inside the SWNT,and its transport through the nanotube is challenging due to the high energy barrier.However,we demonstrate that mechanical vibrations at specific frequencies can effectively drive the ds DNA through the nanotube based on a ratchet effect.The system is driven away from thermal equilibrium,and the spatial inversion symmetry is broken by mechanical vibrations.This study provides valuable insights into the mechanisms of mechanically activated DNA transport and highlights the potential of using SWNTs as nanoscale conduits for ds DNA delivery in nanobiotechnology and biomedicine.
文摘MoS2 nanotube coated SWNT (Single wall carbon nanotube) bundles have been successfully prepared by adsorbing (NH4)2MoS4 onto SWNT bundles and subsequent heat treatment under H2 at 900 ℃ in a tube furnace. The morphologies, structure and composition of the as-prepared sample were investigated by XRD, SEM, HRTEM coupled with EDS. The formation mechanism has also been preliminarily discussed.
