Electrochemical cyclic voltammetric（CV） scan was applied to inducing the partial oxidation and defects of carbon nanotubes（CNTs）.The electrochemically induced functional groups and physical defects were demonstrat...Electrochemical cyclic voltammetric（CV） scan was applied to inducing the partial oxidation and defects of carbon nanotubes（CNTs）.The electrochemically induced functional groups and physical defects were demonstrated to show positive effects on the nanotube capacitance,as exemplified by super-long CNT arrays as model for the easy fabrication of CNT electrodes.Specifically,the initial hydrophobic nanotube surface becomes hydrophilic and a ten-time enhancement in capacitance is observed with respect to the pristine CNT sample.Thus,the electrochemical CV pretreatment can be used as an effective approach to activate the CNT surface for an enhanced electrochemical performance in capacitors,and many other advanced devices beyond capacitors,such as electrochemical sensors and batteries.展开更多
Aqueous rechargeable zinc-ion battery(ZIB)is considered to be a potential energy storage system for large-scale applications due to its environmental friendliness,high safety,and low cost.However,it remains challengin...Aqueous rechargeable zinc-ion battery(ZIB)is considered to be a potential energy storage system for large-scale applications due to its environmental friendliness,high safety,and low cost.However,it remains challenging to develop suitable cathode materials with high specific capacity and long-term cyclic stability.Herein,we have fabricated freestanding Sr0.19V2O51.3H2O/carbon nanotubes(SrVO/CNTs)composite films with different mass ratios by incorporating SrVO into CNTs network.The synthesized SrVO possesses a large interlayer spacing of 1.31 nm,which facilitates Zn(2+)diffusion.Furthermore,the SrVO/CNTs composite film with conductive network structure promotes electron transfer and ensures good contact between SrVO and CNTs during the long-term cycling process.As a result,the battery based on the SrVO/CNTs composite cathode with a mass ratio of 7:3 delivers a specific capacity of 326 mAh·g^(-1)at 0.1 A·g^(-1)and 145 mAh·g^(-1)at 5 A·g^(-1),demonstrating a high capacity and excellent rate capability.Remarkably,the assembled ZIB shows good capacity retention of 91%even after ultra-long cycling for 7500 cycles at a high current rate of 5 Ag^(-1).More importantly,the battery also delivers a high energy density and power density,as 290 Wh·kg^(-1)at 125 W·kg^(-1)(0.1 A·g^(-1)),or 115 Wh·kg^(-1)at 6078 W·kg^(-1)(5 Ag^(-1)).The results demonstrate that the SrVO/CNTs composite is a promising cathode toward large-scale energy storage applications.展开更多
Very long and open aligned carbon nanotubes that reach about 2 mm long, an order of magnitude longer than previously reached, have been prepared by chemical vapor deposition over silica dioxide substrates on the surfa...Very long and open aligned carbon nanotubes that reach about 2 mm long, an order of magnitude longer than previously reached, have been prepared by chemical vapor deposition over silica dioxide substrates on the surface, where iron/silica nano-composite particles are evenly positioned. The nanotubes are naturally opened at the bottom ends. The growth mechanism of the very long and open-ended nanotubes is also discussed.展开更多
Short-Term Memory （STM） is a primary capability of the human brain. Humans use STM to remember a small amount of information, like someone＇s phone number, for a short period of time. Usually the duration of STM is ...Short-Term Memory （STM） is a primary capability of the human brain. Humans use STM to remember a small amount of information, like someone＇s phone number, for a short period of time. Usually the duration of STM is less than 1 minute. Synapses, the connections between neurons, are of vital importance to memory in biological brains. For mimicking the memory function of synapses, Carbon Nanotube （CNT） networks based thin- film transistors with Electric Double Layers （EDL） at the dielectric/channel interface were researched in this work. A response characteristic of pre-synaptic potential pulses on the gate electrode of this CNT synaptic transistor was shown remarkably similar to Excitatory Post-Synaptic Current （EPSC） of biological synapses. Also a multi-level modulatable STM of CNT synaptic transistors was investigated. Post-synaptic current was shown with tunable peak values, on-off ratio, and relaxation time.展开更多
A two-step fringing field dielectrophoretic assembly method for carbon nanotube thin film transistors （CNT-TFTs） fabrication was demonstrated. Densely aligned CNT arrays were assembled at the source and drain electr...A two-step fringing field dielectrophoretic assembly method for carbon nanotube thin film transistors （CNT-TFTs） fabrication was demonstrated. Densely aligned CNT arrays were assembled at the source and drain electrodes sequentially which form a cascade structure of the aligned CNT arrays. The cascade structure reduces the possibility of percolating metallic pathways in the channel, which is beneficial to device performance. In this way, both high on/off current ratio Ion/loft （up to 107） and high out-put current density （8.5μA/μm） were obtained in short channel length （1-2.5μm） CNT-TFTs. The reported CNT assem- bling strategy is site selective and highly efficient, which can be scaled up to large size substrates and leads to high throughput of CNT-TFTs fabrication.展开更多
基金Supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education of China(No.20100732002)the National Natural Science Foundation of China(No.21004006)+2 种基金the Research Foundation for the Doctoral Program of Higher Education of China(No.20101101120036)the 111 Project in China(No.B07012)the Program for the New Century Excellent Talents in Universities of China(No.NCET-10-0047)
文摘Electrochemical cyclic voltammetric（CV） scan was applied to inducing the partial oxidation and defects of carbon nanotubes（CNTs）.The electrochemically induced functional groups and physical defects were demonstrated to show positive effects on the nanotube capacitance,as exemplified by super-long CNT arrays as model for the easy fabrication of CNT electrodes.Specifically,the initial hydrophobic nanotube surface becomes hydrophilic and a ten-time enhancement in capacitance is observed with respect to the pristine CNT sample.Thus,the electrochemical CV pretreatment can be used as an effective approach to activate the CNT surface for an enhanced electrochemical performance in capacitors,and many other advanced devices beyond capacitors,such as electrochemical sensors and batteries.
基金This study was financially supported by the National Natural Science Foundation of China(No 21905037)the Doctoral Research Startup Fund of Liaoning Province(No.2020-BS-066)+2 种基金the Doctoral Research Fund of Lanzhou City University(No.LZCU-BS2020-03)the Fundamental Research Funds for the Central Universities(No.3132019328)Q.L.acknowledges the financial support from China Scholarship Council(CSC).
文摘Aqueous rechargeable zinc-ion battery(ZIB)is considered to be a potential energy storage system for large-scale applications due to its environmental friendliness,high safety,and low cost.However,it remains challenging to develop suitable cathode materials with high specific capacity and long-term cyclic stability.Herein,we have fabricated freestanding Sr0.19V2O51.3H2O/carbon nanotubes(SrVO/CNTs)composite films with different mass ratios by incorporating SrVO into CNTs network.The synthesized SrVO possesses a large interlayer spacing of 1.31 nm,which facilitates Zn(2+)diffusion.Furthermore,the SrVO/CNTs composite film with conductive network structure promotes electron transfer and ensures good contact between SrVO and CNTs during the long-term cycling process.As a result,the battery based on the SrVO/CNTs composite cathode with a mass ratio of 7:3 delivers a specific capacity of 326 mAh·g^(-1)at 0.1 A·g^(-1)and 145 mAh·g^(-1)at 5 A·g^(-1),demonstrating a high capacity and excellent rate capability.Remarkably,the assembled ZIB shows good capacity retention of 91%even after ultra-long cycling for 7500 cycles at a high current rate of 5 Ag^(-1).More importantly,the battery also delivers a high energy density and power density,as 290 Wh·kg^(-1)at 125 W·kg^(-1)(0.1 A·g^(-1)),or 115 Wh·kg^(-1)at 6078 W·kg^(-1)(5 Ag^(-1)).The results demonstrate that the SrVO/CNTs composite is a promising cathode toward large-scale energy storage applications.
文摘Very long and open aligned carbon nanotubes that reach about 2 mm long, an order of magnitude longer than previously reached, have been prepared by chemical vapor deposition over silica dioxide substrates on the surface, where iron/silica nano-composite particles are evenly positioned. The nanotubes are naturally opened at the bottom ends. The growth mechanism of the very long and open-ended nanotubes is also discussed.
基金supported by the National Natural Science Foundation of China(Nos.61574083 and 61434001)the National Key Basic Research and Development(973)Program of China(No.2015CB352100)+3 种基金the National Key Project of Science and Technology(No.2011ZX02403-002)Special Fund for Agroscientic Research in the Public Interest of China(No.201303107)Thankful for the support of the Independent Research Program(2014Z01006)of Tsinghua UniversityAdvanced Sensor and Integrated System Lab of Tsinghua University Graduate School at Shenzhen under project No.ZDSYS20140509172959969
文摘Short-Term Memory （STM） is a primary capability of the human brain. Humans use STM to remember a small amount of information, like someone＇s phone number, for a short period of time. Usually the duration of STM is less than 1 minute. Synapses, the connections between neurons, are of vital importance to memory in biological brains. For mimicking the memory function of synapses, Carbon Nanotube （CNT） networks based thin- film transistors with Electric Double Layers （EDL） at the dielectric/channel interface were researched in this work. A response characteristic of pre-synaptic potential pulses on the gate electrode of this CNT synaptic transistor was shown remarkably similar to Excitatory Post-Synaptic Current （EPSC） of biological synapses. Also a multi-level modulatable STM of CNT synaptic transistors was investigated. Post-synaptic current was shown with tunable peak values, on-off ratio, and relaxation time.
文摘A two-step fringing field dielectrophoretic assembly method for carbon nanotube thin film transistors （CNT-TFTs） fabrication was demonstrated. Densely aligned CNT arrays were assembled at the source and drain electrodes sequentially which form a cascade structure of the aligned CNT arrays. The cascade structure reduces the possibility of percolating metallic pathways in the channel, which is beneficial to device performance. In this way, both high on/off current ratio Ion/loft （up to 107） and high out-put current density （8.5μA/μm） were obtained in short channel length （1-2.5μm） CNT-TFTs. The reported CNT assem- bling strategy is site selective and highly efficient, which can be scaled up to large size substrates and leads to high throughput of CNT-TFTs fabrication.
