A facile impregnation method under mild condition is designed for synthesis of highly dispersed Pt nanoparticles with a narrow size of 4-7 nm on nitrogen-doped carbon nanotubes （CNx）. CNx do not need any pre-surface...A facile impregnation method under mild condition is designed for synthesis of highly dispersed Pt nanoparticles with a narrow size of 4-7 nm on nitrogen-doped carbon nanotubes （CNx）. CNx do not need any pre-surface modification due to the inherent chemical activity. The structure and nature of Pt/CNx were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy spectrum. All the experimental results revealed that the large amount of doped nitrogen atoms in CNx was virtually effective for capturing the Pt（IV） ions. The improved surface nitrogen functionalities and hydrophilicity contributed to the good dispersion and immobi- lization of Pt nanoparticles on the CNx surface. The Pt/CNx served as active and reusable catalysts in the hydrogenation of allyl alcohol. This could be attributed to high dispersion of Pt nanoparticles and stronger interaction between Pt and the supports, which prevented the Pt nanoparticles from aggregating into less active Pt black and from leaching as well.展开更多
Field-effect transistors （FETs） have been fabricated using as-grown single-walled carbon nanotubes （SWNTs） for the channel as well as both source and drain electrodes. The underlying Si substrate was employed as t...Field-effect transistors （FETs） have been fabricated using as-grown single-walled carbon nanotubes （SWNTs） for the channel as well as both source and drain electrodes. The underlying Si substrate was employed as the back-gate electrode. Fabrication consisted of patterned catalyst deposition by surface modification followed by dip-coating and synthesis of SWNTs by alcohol chemical vapor deposition （CVD）. The electrodes and channel were grown simultaneously in one CVD process. The resulting FETs exhibited excellent performance, with an I ON/I OFF ratio of 10^6 and a maximum ON-state current （/ON） exceeding 13 uA. The large I ON is attributed to SWNT bundles connecting the SWNT channel with the SWNT electrodes. Bundling creates a large contact area, which results in a small contact resistance despite the presence of Schottky barriers at metallic-semiconducting interfaces. The approach described here demonstrates a significant step toward the realization of metal-free electronics.展开更多
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.21101105 and No.51174274）, Innovation Program supported by Shanghai Municipal Education Commission （No.12ZZ195 and No.13YZ134）, Shanghai Educational Development Foundation and the Shanghai Municipal Education Commission （No.12CG66）, ＂Shu Guang＂ Project supported by Shanghai Municipal Education Commission （No.09SG54）, and Shanghai Municipal Natural Science Foundation （No.13ZR1454800）.
文摘A facile impregnation method under mild condition is designed for synthesis of highly dispersed Pt nanoparticles with a narrow size of 4-7 nm on nitrogen-doped carbon nanotubes （CNx）. CNx do not need any pre-surface modification due to the inherent chemical activity. The structure and nature of Pt/CNx were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy spectrum. All the experimental results revealed that the large amount of doped nitrogen atoms in CNx was virtually effective for capturing the Pt（IV） ions. The improved surface nitrogen functionalities and hydrophilicity contributed to the good dispersion and immobi- lization of Pt nanoparticles on the CNx surface. The Pt/CNx served as active and reusable catalysts in the hydrogenation of allyl alcohol. This could be attributed to high dispersion of Pt nanoparticles and stronger interaction between Pt and the supports, which prevented the Pt nanoparticles from aggregating into less active Pt black and from leaching as well.
文摘Field-effect transistors （FETs） have been fabricated using as-grown single-walled carbon nanotubes （SWNTs） for the channel as well as both source and drain electrodes. The underlying Si substrate was employed as the back-gate electrode. Fabrication consisted of patterned catalyst deposition by surface modification followed by dip-coating and synthesis of SWNTs by alcohol chemical vapor deposition （CVD）. The electrodes and channel were grown simultaneously in one CVD process. The resulting FETs exhibited excellent performance, with an I ON/I OFF ratio of 10^6 and a maximum ON-state current （/ON） exceeding 13 uA. The large I ON is attributed to SWNT bundles connecting the SWNT channel with the SWNT electrodes. Bundling creates a large contact area, which results in a small contact resistance despite the presence of Schottky barriers at metallic-semiconducting interfaces. The approach described here demonstrates a significant step toward the realization of metal-free electronics.
