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Liu E.,Tianjin University | Liu E.,Tianjin Key Laboratory of Composite and Functional Materials | Wang J.,Tianjin University | Wang J.,Tianjin Key Laboratory of Composite and Functional Materials | And 11 more authors.
International Journal of Hydrogen Energy | Year: 2011

Electrochemical hydrogen storage of multi-walled carbon nanotubes (MWCNTs) decorated by TiO2 nanoparticles (NPs) has been studied by the galvanostatic charge and discharge method. The TiO2 NPs are deposited on the surface of MWCNTs by sol-gel method. Structural and morphological characterizations have been carried out using XRD, SEM and TEM, respectively. TiO2 NPs can significantly enhance the discharge capacity of MWCNTs. The cyclic voltammograms analysis indicates that the electrical double layer contributes little to the discharge capacity of TiO2-decorated MWCNTs. The MWCNTs modified with a certain amount of TiO2 NPs have a discharge capacity of 540 mAh/g, corresponding to an electrochemical hydrogen storage capacity of about 2.02 wt%, which is quite interesting for the battery applications. The enhancement effect of TiO2 NPs on the discharge capacity of MWCNTs could be related to the increased effective area for the adsorption of hydrogen atoms in the presence of TiO2 NPs on MWCNTs and the preferable redox ability of TiO2 NPs. Copyright © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source


Yu Y.,Tianjin University | Yu Y.,Tianjin Key Laboratory of Composite and Functional Materials | Zhao N.,Tianjin University | Zhao N.,Tianjin Key Laboratory of Composite and Functional Materials | And 9 more authors.
International Journal of Hydrogen Energy | Year: 2012

The electrochemical hydrogen storage of expanded graphite (EG) decorated with TiO2 nanoparticles (NPs) calcined at different temperatures has been investigated with the galvanostatic charge and discharge method. The TiO2 NPs are deposited on and between the graphene-like nanosheets of EG by a sol-gel method. The morphology, structure, composition, and specific surface area of the samples were characterized. The electrochemical measurement reveals that the EG decorated with TiO2 NPs calcined at 500 °C has a discharge capacity of 373.5 mAh/g which is 20 times higher than that of pure EG and quite appealing for the battery applications. The mechanism of enhancement of the electrochemical activity for the TiO2-decorated EG could be attributed to the preferable redox ability and photocatalytic property of TiO2 NPs. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights. Source


Wu S.,Tianjin University | Feng J.-M.,Key Laboratory of Advanced Ceramics and Machining Technology | Fu X.,Tianjin University | Hu X.-D.,Tianjin University | And 3 more authors.
Nanotechnology | Year: 2011

Controlled placement of carbon nanotubes is important for carbon-based nanodevice assembly. However, it is difficult to manipulate individual nanotubes because of their extremely small dimensions. Ultra-fine tubes are often in the form of bundles and are hard to efficiently move on a surface due to the strong adhesion among themselves and between the tubes and the substrate. This paper presents a novel manipulation approach of individual double-walled carbon nanotubes encased in a thick amorphous carbon shell. With an atomic force microscope, we are able to freely displace the nanotubes within a casing shell, and unpack it from the shell on a silicon surface. The theoretical analysis demonstrates that the unpacking process is determined by the difference of the static friction between the shell and the substrate and the resistance force between the shell and the embedded nanotube. © 2011 IOP Publishing Ltd. Source


Su D.,Key Laboratory of Advanced Ceramics and Machining Technology | Duan H.-Z.,Key Laboratory of Advanced Ceramics and Machining Technology
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2015

Polyzirconosiloxane (PZSO) fibers were obtained from silicon alkoxide solution consisting of tetraethoxylsilane (TEOS) and dimethyldiethoxylsilane (DMDES) using ZrOCl2 as zirconium source by sol-gel process, and the spinnability of the solution were optimized by varying the amount of ZrOCl2 and H2O. Subsequent drying and pyrolysis treatment of the PZSO gel fibers yields SiZrOC fibers with high ceramic yield of 84.7wt% at 1000℃. Scanning electron microscopy shows that SiZrOC fibers are smooth and dense, and maintain the initial round shape of PZSO fibers. FTIR analysis shows Zr is incorporated into Si-O tetrahedron suggesting the formation of =Zr-O-Si≡ bridge through co-condensation of ZrOCl2, TEOS and DMDES. SiZrOC fibers exhibit less than 5wt% weight loss under heat-treating up to 1500℃ in flowing argon indicating their good thermal stability in high temperature. ©, 2015, Chinese Ceramic Society. All right reserved. Source


Qin M.,Tianjin University | Feng Y.,Tianjin University | Feng Y.,Key Laboratory of Advanced Ceramics and Machining Technology | Feng Y.,Tianjin Key Laboratory of Composite and Functional Materials | And 4 more authors.
Carbon | Year: 2016

A three-dimensional (3D) carbon nanotube/exfoliated graphite block (CNT/EGB) was prepared by growing vertical aligned carbon nanotube (VACNT) at the surface of SiO2-coated exfoliated graphite plate (EGP) through chemical vapor deposition followed by hot-pressing. In such 3D CNT/EGB, EGPs were bridged by the VACNTs in the cross-plane direction, and the interface between EGPs and VACNTs was covalently bonded by SiC which formed by reaction of SiO2 and the adjacent carbon of EGPs and VACNTs. The length and growth density of VACNTs were adjusted by the growth time and concentration of catalysts. Thermal conductivity and mechanical strength of CNT/EGB were controlled by the growth states of VACNTs and hot-pressing. CNT/EGB showed a maximum cross-plane thermal conductivity (k⊥) of 38 W/mK, which is more than twice as much as that of EGB (14 W/mK). A remarkable increase in k⊥ was attributed to the efficient heat flow of VACNTs bridging EGPs in the cross-plane direction and the thermal conductive SiC interface between VACNTs and EGPs. Additionally, the increased bending (76 MPa) and compressive strength (59 MPa) of CNT/EGB was due to the combination of strong pull-out effect of high-density nanotubes and the strong covalent interconnections between VACNTs and EGPs. © 2016 Elsevier Ltd. All rights reserved. Source

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