Single-walled carbon nanotube embedded porous carbon nanofiber with enhanced electrochemical capacitive performance

Active carbon nanofibers (CNFs) with porous structure show highly electrochemical double-layer capacitance for supercapacitors because of their large specific area. However, their poor crystallization induced the low conductivity, which could largely limit the electrochemical performance of the porous CNFs. In this research, porous CNFs with single-walled carbon nanotubes (SWCNTs) were prepared by electrospinning and high temperature carbonization. The introduction of SWCNTs into porous CNFs could largely enhance the conductivity of the porous CNF nanotextiles, thus the electrochemical performance of the composite nanotextile was largely enhanced. The specific capacitance of the composite could achieve 417 F/g at a current density of 0.5 A/g, and keep 193 F/g at the high current density of 10 A/g. Furthermore its specific capacitance could keep 96% after 2000 cycles of charge/discharge at the current density of 10 A/g. This nanotextile could be a promising candidate for the binder-free and filler-free electrodes of high-performance supercapacitors. (C) 2015 Elsevier B.V. All rights reserved

Rational control on floating catalysts for the growth of carbon nanotube assemblies: From vertically aligned carbon nanotube arrays to carbon nanotube films

Floating catalyst chemical vapor deposition (FCCVD) has been widely used for the growth of various carbon nanotube (CNT) macrostructures, mainly including vertically aligned CNT (VACNT) arrays and none-woven CNT films. However, it is still unclear for the reason why these CNT macrostructures with largely different morphologies were received via the similar method. In this research, it revealed that the growth temperature largely affected the nucleation status of floating catalysts and thus controlled the morphologies of CNT macrostructures from VACNT arrays to none-woven CNT films. In low temperatures (below 800 degrees C), VACNTs were grown by bottom-up mechanism with several CNTs, but not one individual from bottom to up along the array height direction. Furthermore, VACNT arrays were only grown on some substrates that can induce iron atoms aggregating to catalyst particles with a suitable size. When increasing the growth temperature higher than 800 degrees C, more catalyst particles were nucleated in the gas flow, which induced the formation of none-woven CNT films composed of thin CNTs (single-walled CNTs and double-walled CNTs). This research was significative for understanding CNT growth mechanism via FCCVD process and the synthesis of different CNT macrostructures by this strategy. (C) 2015 Elsevier B.V. All rights reserved

Facile synthesis and characterization of Au-Cu, Pt-Cu nanotubes by sacrificial template method

Bimetallic nanotubes with noble metals have already shown more versatile performances than single-metallic nanotubes. However, most of the current methods to prepare bimetallic nanotubes are based on existed hard template, which could not be easily removed after the formation of bimetallic nanotubes. It is still a challenge for synthesizing bimetallic nanotubes without the template removing subsequently. In this research, we developed a novel method to prepare noble metal-copper (Cu) bimetallic nanotubes with Cu nanowires as the sacrificial template. The aqueous solutions with chloroauric acid or palladium chloride were used to bring displacement reaction with Cu nanowires. The simultaneous alloying effect and Kirkendall effect result in hollow nanostructures. The Cu nanowire was converted to a bimetallic hollow with Au-Cu or Pt-Cu alloy nanotubes. This facile method could achieve large-scale preparation of bimetallic nanotubes with noble metals. Furthermore, this alloy nanotube shows superior electrochemical catalytic performance than single-metallic nanoparticles. (C) 2014 Elsevier Ltd. All rights reserved

Carbon Nanotube/Graphene Hybrid Nanostructures and Their Application in Supercapacitors

In this paper, we review the preparation methods of carbon nanotube (CNT)/graphene composite materials for the electrode of supercapacitors, and introduce the developments of CNT/graphene/pseudocapacitive material ternary composite materials with highly electrochemical performance. The rational designed CNT/graphene composite nanostructures could largely utilize the characteristics of carbon nanomaterials for electrochemical double-large supercapacitors, such as large specific area, high conductivity and befitting porous structure, and also achieve large mass loading of pseudo-capacitive materials with high dispersion for pseudocapacitors. As a result, these composite materials are promising candidates for the electrode materials of high-performance supercapacitors with high capacitance, excellent rate performance and long lifetime

Electrochemical conversion of Ni-2(OH)(2)CO3 into Ni(OH)(2) hierarchical nanostructures loaded on a carbon nanotube paper with high electrochemical energy storage performance

Large-diameter carbon nanotube (CNT) paper was used as a porous and conductive template to obtain vertically aligned Ni-2(OH)(2)CO3 nanowire array shells, which could be further converted into highly active Ni(OH)(2) nanosheets by a cyclic voltammetry strategy. The as-prepared hierarchical nanostructure showed superior electrochemical performance for the electrodes of supercapacitors

Porous reduced graphene oxide wrapped carbon nanotube-manganese dioxide nanocables with enhanced electrochemical capacitive performance

MnO2 has ultra-low conductivity for electrodes of supercapacitors. In this research, porous reduced graphene oxide (rGO) wraps on MnO2 nanoflowers with a conductive carbon nanotube core (CNTMnO2). This nanostructure could effectively improve the surface and inner conductivity of the composites. Unlike pristine rGO, the porous rGO does not block the diffusion of electrolyte into the inner part of the composites, which allows the utilization of MnO2 in this composite capacitor very well. As a result, the as-prepared CNT-MnO2-porous rGO ternary hybrid material shows superior specific capacitance and rate performance to pristine CNT-MnO2 nanocables and pristine rGO wrapped CNTMnO2 nanocables. This synthesis strategy could be valuable for the design of better performance pseudocapacitive electrodes for supercapacitors

Carbon Nanotube/Cu Nanowires/Epoxy Composite Mats with Improved Thermal and Electrical Conductivity

Polymer composites with carbon nanofillers have been regarded as a promising candidate for electronic package materials. The challenge for such materials is to increase the electrical and thermal conductivity of the composites. Herein, we reported an epoxy composite film with high thermal and electrical conductivity that were prepared by loading high volume fraction. of well-dispersed multiwalled carbon nanotubes (MWCNTs, around 50 nm in diameter, 1-10 mu m in length) and copper nanowires (Cu NWs, 60-70 nm in diameter, 1-5 mu m in length) in epoxy matrix. The MWCNT-Cu NW hybrid mats were prepared by a vacuum filtration method with an optimum Cu NW content of 50 wt%. The hybrid mats was then impregnated by epoxy solution to prepare epoxy composite films. The epoxy was modified by the toughening agent to make the composite films tough and flexible. The loading fraction of MWCNTs and Cu NWs was tuned by controlling the viscosity of epoxy solution. A remarkable synergetic effect between the MWCNTs and Cu NWs in improving the electrical and thermal conductivity of epoxy composites was demonstrated. The results showed that the electrical conductivity of nanocomposites with 42.5 wt% epoxy was 1500 S/m, and the thermal conductivity was 2.83 W/m K, which was 10.1 times of the neat epoxy. Its thermal resistance was as low as 1% of the pure epoxy. And the mechanical properties of composites were also investigated. These robust and flexible nanocomposites showed prospective applications as thermal interface materials (TIMs) in the electronic industry

One-step strategy to a three-dimensional NiS-reduced graphene oxide hybrid nanostructure for high performance supercapacitors

Metal sulfides are an emerging class of high-performance electrode materials for electrochemical energy storage devices. Here, a facile hydrothermal method is reported to assemble three-dimensional (3D) NiS-reduced graphene oxide (rGO) hybrid aerogels with strong coupling between the two compounds. It is intriguing to note that NiS nanoparticles are well anchored on the 3D porous and conductive scaffold constructed from wrinkled rGO nanosheets. When evaluated as binder-free electrode materials for supercapacitors, impressive electrochemical performances are presented. Specifically, the 3D NiS-rGO aerogel nanocomposite exhibits a high capacitance of 852 F g(-1), 526 F g(-1) based on the whole electrode mass (m(NiS) : m(GO) = 45 mg/50 mg) at a current density of 2 A g(-1) and 15 A g(-1), respectively. These satisfactory electrochemical behaviors, attributed to the introduction of reduced graphene oxide, suggest the great promise of fabricating graphene-supported hybrid electrode materials for high-performance energy applications

The Application of Nano Carbon Based Materials in Electrical Conductive Adhesives

Nowadays people have a fancy for good electrically and thermally conductivity adhesives because they have wide applications compared with the ordinary adhesives, especially in the field of electronic packaging. However, the cost is subject to high volume content of the metal fillers, which can't be reduced effectively. This review summarizes the latest research work and analyzes the reported methods aimed to solve this kind of problem in recent years. Nanocarbon materials, such as carbon nanotubes (CNTs) and graphene, have excellent electrical, mechanical and thermal properties, which have been widely used as fillers in the composites. By mixing them with metal fillers, it is able to reduce 10 wt% similar to 20 wt% content of metal fillers. Especially, CNTs as one-dimensional nano material could bridge the neighboring conductive metal fillers for both reducing the metal content and effectively improving the electrical, mechanical and thermal properties of as-prepared composites. By choosing different polymer matrixes such as thermal plastic and thermal set resin, the mechanical properties of the adhesive can be further improved and satisfy with the packaging requirements of flexible electrical devices. In addition, we think that it is a good way to improve the electrical and thermal properties by sintering the nanoparticles at high temperature, which are synthesized by chemistry reaction

Hierarchical carbon nanotube/alpha-Ni(OH)(2) nanosheet composite paper with enhanced electrochemical capacitance

<span lang="EN-US" style="font-family: &quot;Calibri&quot;,&quot;sans-serif&quot;; font-size: 10.5pt; mso-bidi-font-size: 11.0pt; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: &quot;Times New Roman&quot;; mso-bidi-theme-font: minor-bidi; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA;"><font color="#000000">Carbon nanotube (CNT)/alpha-Ni(OH)(2) composite paper based on CNT paper was prepared by a facile chemical bath deposition (CBD) method. alpha-Ni(OH)(2) nanosheets were vertically grown on individual CNTs in CNT paper to form hierarchical nanowires. The loading mass of alpha-Ni(OH)(2) in the composite paper could be 66 wt%. Thus the composite paper showed much higher specific surface area than that of pristine CNT paper. This novel structure brings the composite paper an electrochemical capacitance high to 1144 F/g at the current density of 0.5 A/g, and maintains 585 F/g at 10 A/g. This composite paper could be a promising candidate for the electrodes of high-performance supercapacitors. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.</font></span