Co-reporter:Shuaishuai Han, Feng Hou, Xubo Yuan, Jiachen Liu, Xiao Yan, Shunquan Chen
Electrochimica Acta 2017 Volume 225(Volume 225) pp:
Publication Date(Web):20 January 2017
DOI:10.1016/j.electacta.2016.12.159
•A simple step for large quantities production are used to fabricate electrode composite materials.•Hybrid films of 3D hierarchical structures can be prepared by direct spinning CVD process.•An extended conjugated network can be developed with CNTs connecting rGO sheets.•Hybrid films receive more than triple specific capacitances compared to pure CNT films.3D hierarchical carbon nanotube/reduced graphene oxide (CNT/rGO) hybrid films of enhanced electrochemical performance are obtained, by dispersing graphene oxide (GO) sheets into ethanol carbon source, ferrocene as catalyst and thiophene as promoter, the hybrid films are fabricated in novel direct injection floating catalyst chemical vapor deposition (CVD) method. With the addition of the rGO sheets, the hybrid films with enhanced surface area still retain the connecting structures of CNT networks. The resulting CNT/rGO films exhibit high specific capacitances of 151 F/g in 2 M KOH aqueous solution and 80 F/g in 1 M Na2SO4 aqueous solution under the scan rate of 5 mV/s, respectively. The hybrid films with low content of rGO sheets receive more than triple specific capacitances as compensation for the pure CNT films. In addition, the capacitance retention of 97% after 5000 cycles demonstrates an excellent cycling property. These results indicate a promising material for scalable products to capacitive applications.Download high-res image (162KB)Download full-size image
Co-reporter:Xin Wang, Anran Guo, Jiapeng Liu, Yuanyuan Wang, Jiachen Liu, Haiyan Du, Feng Hou
Ceramics International 2016 Volume 42(Issue 11) pp:13161-13167
Publication Date(Web):15 August 2016
DOI:10.1016/j.ceramint.2016.05.107
Abstract
The method of in situ synthesis of mullite whiskers by gas-phase deposition and reaction was applied to improve the compressive strength of the mullite fiber brick. During the preparation process, silica sol, Al(NO3)3 solution and NH4F solution were introduced into the fibrous brick in the form of ions or sol through vacuum impregnation and freeze drying, and the silica sol, Al(NO3)3 and NH4F served as the silica sources, aluminum source and catalyst, respectively. Effects of process parameters (concentration of impregnation solutions, holding time, sintering temperature) on compressive strength and elastic modulus of the fibrous brick during the in situ toughening process were analyzed. SEM and XRD analysis results demonstrated that the mullite whiskers were synthesized on the surface of mullite fibers based on the reaction of AlOF and SiF4. What is more, the whiskers on adjacent fibers intersected with each other and formed many unfixed lap-jointing points, resulting in the increase of compressive strength and elastic modulus. Although the density and thermal conductivity of the sample after the generation of mullite whiskers fabricated with the optimum process were 0.406 g/cm3 and 0.1262 W/(m K), respectively, which were slightly higher than that of the raw fibrous brick (0.375 g/cm3 density and 0.1069 W/(m K) thermal conductivity, respectively), the corresponding compressive strength and elastic modulus of the sample reinforced with the whiskers increased to 1.45 MPa and 42.03 MPa, respectively, which were much higher than that of the raw fibrous brick (0.39 MPa compressive strength and 6.5 MPa elastic modulus).
Co-reporter:Hongxu Gao, Feng Hou, Zhipeng Wan, Sha Zhao, Deming Yang, Jiachen Liu, Anran Guo, Yuxuan Gong
Electrochimica Acta 2015 Volume 154() pp:321-328
Publication Date(Web):1 February 2015
DOI:10.1016/j.electacta.2014.12.068
•CNTs/TiO2 compoiste films synthesized are continuous and free-standing.•The film can be directly used as flexible, binder-free Lithium-Ion Battery electrode.•The CNTs/TiO2 electrodes exhibit excellent rate capacity and cyclic stability.•Our strategy is readily applicable to fabricate other CNTs-based composite films.Continuous free-standing Carbon Nanotubes (CNTs)/Titanium oxide (TiO2) composite films were fabricated in a vertical CVD gas flow reactor with water sealing by the One-Step Chemical Vapor Deposition (CVD) approach. The composite films consist of multiple layers of conductive carbon nanotube networks with titanium oxide nanoparticles decorating on carbon nanotube surface. The as-synthesized flexible and transferrable composite films show excellent electrochemical properties, when the content of tetrabutyl titanate is 19.0 wt.%, which can be promising as binder-free anodes for Lithium-Ion Battery (LIB) applications. It demonstrates remarkably high rate capacity of 150 mAh g−1, as well as excellent high rate cyclic stability over 500 cycles (current density of 3000 mA g−1). Such observations can be attributed to the relatively larger surface area and pore volume comparing with pristine CNT films. Great potentials of CNTs/TiO2 composite films for large-scale production and application in energy devices were shown.
Co-reporter:Shanshan Xu, Deming Yang, Fan Zhang, Jiacheng Liu, Anran Guo and Feng Hou
RSC Advances 2015 vol. 5(Issue 90) pp:74032-74039
Publication Date(Web):27 Aug 2015
DOI:10.1039/C5RA12855B
Herein, we demonstrated facile fabrication of NiCo2O4 nanoparticles on a CNT film by a chemical deposition method, followed by thermal annealing treatment processing. The synthesized NiCo2O4/CNT nanocomposite films were still highly flexible, porous, and conductive. Scanning electrical microscopy (SEM) and transmission electronic microscopy (TEM) observation showed that the web-like structure of the films is still preserved and each carbon nanotube in the film was uniformly wrapped by ball-like nanoparticles (ca. 5 nm). X-Ray Diffraction (XRD) measurement confirmed that spinel NiCo2O4 was successfully synthesized during the experiment. The contents of NiCo2O4 in the composite films could be controlled by tuning the deposition times. The flexible, porous and conductive nanocomposite films could be employed as high-performance flexible energy saving installments. The three-pole measurements illustrated that the composite films possessed a capacitance of 828 F g−1 at 1 A g−1, and retained over 99% of their capacitance after 3000 cycles of charge/discharge at 5 A g−1, showing high-performance electrochemical properties. Finally, an asymmetric supercapacitor installment was assembled by using the composite film as the positive electrode and commercially available activated carbon (AC) as the negative electrode. The measurement gave an energy density of 28.58 W h kg−1 at a power density of 0.7 kW kg−1.
Co-reporter:Deming Yang, Shanshan Xu, Shuilang Dong, Jiachen Liu, Anran Guo, Xiao Yan and Feng Hou
RSC Advances 2015 vol. 5(Issue 129) pp:106298-106306
Publication Date(Web):09 Dec 2015
DOI:10.1039/C5RA21609E
Continuous Fe nanoparticles (NPs)/carbon nanotube (CNTs) composite films have been fabricated with the CVD gas flow reaction using ferrocene as a catalyst and ethanol as a carbon precursor. The as-spun Fe NPs/CNTs films are converted to Fe2O3 NPs/CNTs films by an annealing process in air at a temperature of 500 °C. The as-prepared Fe2O3 NPs/CNTs films are still highly flexible. Scanning electron microscopy (SEM) and transmission electron microscopy observations reveal the Fe2O3 NPs are homogeneously bonded with the CNT network. In addition, the flexible and conductive 3D CNTs networks endow the as-synthesized composite with increased electrical conductivity and mechanical stability. As a result, the as-synthesized flexible and transferrable composite films deliver an initial reversible capacity of 985.8 mA h g−1 at a current density of 30 mA g−1, and maintain a high reversible capacity of 392.4 mA h g−1 even at a current density up to 3 A g−1. Meanwhile, Fe2O3 NPs/CNTs films exhibit an excellent cycling performance with a reversible capacity of 375.5 mA h g−1 after 800 cycles at a current density of 3 A g−1.
Co-reporter:Hongxu Gao, Feng Hou, Xuerong Zheng, Jiachen Liu, Anran Guo, Deming Yang, Yuxuan Gong
Vacuum 2015 Volume 112() pp:1-4
Publication Date(Web):February 2015
DOI:10.1016/j.vacuum.2014.10.017
•As-synthesized carbon nanotube films are continuous and free-standing.•The films can be used as flexible, binder-free electrode for lithium-ion battery.•Defective carbon nanotube is favorable to enhance reversible capacity of CNT film.Carbon nanotube films (CNT-1 and CNT-2) were fabricated in a vertical CVD gas flow reactor with water sealing. CNT-1 films consist of ordered crystalline carbon nanotubes, while CNT-2 are defective carbon nanotube films. The films are flexible and transferrable and can be used as binder-free anodes for lithium-ion batteries (LIB). Electrochemical measurements show that CNT-2 possess a reversible capacity of 452 mA h g−1 under a current density of 30 mA g−1, which is higher than that of CNT-1 (375 mA h g−1) under the same current density. In addition, the CNT-2 shows a reversible capacity of 107.9 mA h g−1 after 500 cycles at a current density of 3000 mA g−1, while 82.1 mA h g−1 for CNT-1 under the same condition. Good correlations between morphological factors, defective structure and electrochemical performance are observed.
Co-reporter:Shan Liu, Jiachen Liu, Haiyan Du, Feng Hou, Sue Ren and Haitao Geng
RSC Advances 2014 vol. 4(Issue 19) pp:9451-9456
Publication Date(Web):24 Jan 2014
DOI:10.1039/C3RA47394E
Mullite fibres/whiskers frameworks (MF/MW frameworks) were prepared by mixed-slurry-filtration and heat-treating. Hierarchical fibres/whiskers structure formed in the frameworks through fluorine-catalyzed gas-phase reaction. Topaz rods as a transient product first formed in the frameworks, and then gradually transformed into mullite whiskers. Intersected mullite whiskers served as lap-jointing points of the fibres. The volume density, apparent porosity and thermal conductivity of the samples heat-treated at 1100–1500 °C were 0.402–0.541 g cm−3, 81.2–85% and 0.1191–0.1647 W m−1 k−1, respectively. Cyclic compression–resilience performance (maximum stress = 0.4 MPa) of the samples was tested at room temperature. The compression ratio, permanent deformation ratio and resilience ratio of the samples in the first circle compression–resilience test were 2.031–3.833%, 0.125–0.042% and 93.85–98.28%, respectively. The excellent thermal/mechanical properties indicated that the MF/MW frameworks were suitable for being applied as high temperature heat-insulation/sealing materials.
Co-reporter:Shan Liu, Jiachen Liu, Haiyan Du and Feng Hou
RSC Advances 2014 vol. 4(Issue 46) pp:24307-24310
Publication Date(Web):14 May 2014
DOI:10.1039/C4RA01196A
Hierarchical structural silica-fiber-woven/mullite-whisker material was prepared by surface etching and gas-phase reaction. In the material, the silica-fiber-woven served as the substrate, and a mass of mullite whiskers grew on the silica fibers by fluorine-catalyzed gas-phase reactions (mixed AlF3–SiO2 powders were used as the raw material). The silica-fiber-woven was first etched by fluorine-rich gas, which was produced in the gas-phase reaction. The etching pits on the silica fibers offered nucleate sites for the mullite whiskers' growth. The volume density, tensile strength and thermal conductivity of the hierarchical structural silica-fiber-woven/mullite-whisker material were 0.572 g cm−3, 0.441 MPa and 0.1233 W m−1 K−1, respectively, indicating the suitability of the material for use as a heat-sealing/insulation gasket at high temperatures.
Co-reporter:Liubing Dong, Yang Li, Lei Wang, Shanshan Xu, Feng Hou
Materials Letters 2014 130() pp: 180-183
Publication Date(Web):
DOI:10.1016/j.matlet.2014.05.116
Co-reporter:Liubing Dong, Yang Li, Lei Wang, Feng Hou, Jiachen Liu
Materials Letters 2014 130() pp: 292-295
Publication Date(Web):
DOI:10.1016/j.matlet.2014.05.135
Co-reporter:Liubing Dong, Feng Hou, Yang Li, Lei Wang, Hongxu Gao, Yanlong Tang
Composites Part A: Applied Science and Manufacturing 2014 Volume 56() pp:248-255
Publication Date(Web):January 2014
DOI:10.1016/j.compositesa.2013.10.016
In order to optimize carbon nanotube (CNT) dispersion state in fiber/epoxy composite, a novel kind of CNT organization form of continuous networks was designed. The present work mainly discussed the feasibility of preparing continuous CNT networks in composite: Fiber fabric was immersed into CNT aqueous solution (containing dispersant) followed by freeze drying and pyrolysis process, prior to epoxy infusion. The morphologies of fabric with CNTs were observed by Scanning Electron Microscope. The relationship between CNT networks and flowing epoxy resin was studied. Properties of composite, including out-of-plane electrical conductivity and interlaminar shear strength (ILSS), were measured. The results demonstrated that continuous and porous CNT networks formed by entangled CNTs could be assembled in fiber fabric. Most part of them were preserved in composite due to the robustness of network structures. The preserved CNT networks significantly improved out-of-plane electrical conductivity, and also have an effect on ILSS value.
Co-reporter:Liubing Dong, Feng Hou, Xiaohua Zhong, Rui Wang, Jin Chen, Lei Wang
Composites Part A: Applied Science and Manufacturing 2013 Volume 55() pp:74-82
Publication Date(Web):December 2013
DOI:10.1016/j.compositesa.2013.08.007
Carbon fiber felt with carbon nanotubes (CNTs) were prepared by immersing three-dimensional (3D) felt into CNT aqueous solution (with dispersant) followed by removing water with different drying methods. Epoxy resin was then introduced into the felt to obtain 3D fiber felt/CNTs modified epoxy composites. This paper highlights the effect of drying method on macro-morphologies of the felt, morphological dispersion of CNTs and some relevant properties of the composites, including electrical conductivity and flexural performance. The results demonstrate that compared to the commonly used heat drying method, freeze drying technique possesses obvious advantages for the fabrication of fiber felt/CNT modified epoxy composites.
