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Performance of a mechanical buffer can be significantly improved by strengthening the materials and optimizing its structure. Manufacturing of high-strength and light-weight foam-filled tubes (FFTs) has been proved to be an ingenious strategy. In this work, the in situ grown carbon nanotubes (CNTs) were used to reinforce aluminum (Al) foams. The FFTs were prepared by inserting CNT/Al composite foams (CFs) into 6061 Al alloy empty tubes (ETs). The crushing behavior and energy absorption property of the as-prepared CNT/Al FFTs (C-FFTs) were evaluated using uniaxial compressive tests. The results show that the adopted CFs can effectively interact with outside tubes in C-FFTs. The C-FFTs significantly improve the compressive performance and energy absorption property, but only slightly increase the structure weight compared to single ETs. The plateau stress and energy absorption capacity of C-FFTs are nearly 3.5 and 3.7 times higher than those of ETs, respectively. This phenomenon is ascribed to the stable support of CFs and the excellent load transfer ability of CNTs. [ABSTRACT FROM AUTHOR]

The compression‐compression fatigue performance of carbon nanotube (CNT) reinforced aluminium matrix composite foams (AMCFs) were investigated. The ε‐N curves of AMCFs are composed of three stages (the elastic, strain hardening, and rapid accumulation stages), while the fatigue strain of AMCFs accumulates very rapidly in stage III compared with Al foams. The fatigue strength of AMCFs with CNT contents of 2.0, 2.5, and 3.0 wt% increases by 6%, 44%, and 102% than Al foams, respectively. Different from Al foams' deformation of layer‐by‐layer, the main failure modes of AMCFs are the brittle fracture and collapse of pores within significant shear deformation bands under fatigue loading. The uniform distribution of CNTs and good interfacial bonding of CNTs and Al matrix is the important factor for the improvement of fatigue properties of AMCFs. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT)/metal interface interaction is critical to the mechanical properties of CNT-reinforced metal matrix composites (MMCs). In this paper, in order to realize the chemical modification of the interface interaction between CNTs and Mg matrix, different types of defects (monovacancy, carbon and oxygen adatoms, as well as p-type boron and n-type nitrogen substitution) are introduced in CNTs to investigate the effect of the defects on the interface interaction (Eib) between CNT and Mg (0 0 0 1) surface. Moreover, two models (adsorption model and interface model) are compared and validated to investigate the interface interaction. It is revealed that the CNT with the carbon adatom has the highest Eib with the Mg (0 0 0 1), and the effect of boron doping on Eib is superior to the intermediate oxygen which has already been proved experimentally in the enhancement of the interface interaction in MMCs. In terms of the electronic structure analysis, we reveal the micro-mechanism of the increase of Eib under the action of different types of defects, and propose that the presence of holes (boron dopant) and the unsaturated electrons in CNTs can generate the chemical interaction between CNT and Mg matrix effectively. Our results are of great scientific importance to the realization of robust interfacial bonding between CNTs and Mg matrix via the reinforcement modification, so as to enhance the mechanical properties of CNTs reinforced Mg matrix composites. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT) reinforced Al composite foams with different CNT contents are fabricated through an improved powder metallurgy approach by combining in-situ chemical vapor deposition (CVD), short time ball-milling, and space-holder method. The CNTs are uniformly dispersed on the surface of Al particles by in-situ CVD process, followed by a short time ball-milling process enabling an excellent interfacial bonding between CNTs and the Al matrix. The pore size and microstructures of the composite foams can be well tailored by the carbamide particle templates. The yield strength and energy absorption capacity of composite foams reach 18.1 MPa and 15.8 MJ m−3 with 3.0 wt% CNT addition, which are ≈1.3 and ≈3.6 times higher than those of pure Al foam, respectively. The energy absorption efficiency of the CNT/Al composite foams achieves a maximum of ≈0.86, when the CNT content is up to 3.0 wt%. Additionally, compressive and energy absorption properties of the CNT/Al composite foams increase with the increment of relative density. The failure mode of the Al foam changes from plastic mode to brittle mode combined with ductile mode, as a result of CNT addition. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs)/Al interface interaction is critical to the mechanical properties of CNT-reinforced Al matrix composites. In this study, the effect of different defects (oxygen and carbon adatoms, n-type N substitution and p-type B substitution) on the interactions between a (5, 5) CNT and an Al (111) surface is studied based on first-principles total energy calculations. It is found that the defects can enhance the interaction between the CNT and Al (111) surface in different degree due to the different valence electron configurations of the interfacial defect atoms, as well as the different influences of the defects on the electronic structures of the CNT. The results are helpful for the improvement of the interfacial interactions between CNTs and Al matrix via the introduction of the defects at the interface to enhance the mechanical properties of CNT-reinforced Al matrix composites. [ABSTRACT FROM AUTHOR]

The damping properties of Al matrix composite foams reinforced by in-situ grown carbon nanotubes (CNTs) have been investigated. The results show that the damping capacity of the CNT/Al composite foams is visibly enhanced with the CNT addition. The loss factors of the composite foams are found not only increase with the increment of CNT content but also increase with the porosity raising. For the 3.0 wt%-CNT/Al composite foams, the loss factor keeps the level of ∼0.26 at 25–200 °C and further increases to 0.36 when the temperature is elevated to 390 °C, which is ∼2.71 and 1.77 times higher than that of the pure Al foam, respectively. The damping improvement of CNT/Al composite foams is mainly due to the high inherent damping of CNTs and the formation of large numbers of well-bonded CNT-Al interfaces. [ABSTRACT FROM AUTHOR]

Highlights: [•] A mass of amorphous carbon nanotubes have been synthesized. [•] The Fe76Si9B10P5 particles were employed as both the catalyst and support. [•] C2H2 and Ar were employed as carbon precursor and carrier gas, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Novel binary and triple carbon nanotubes (CNTs) with one common catalytic particle encapsulated have been synthesized using Ni/Cu/Al2O3 catalyst, which was produced by a sol–gel method. But when using Ni/Al2O3 as catalyst, a mass of common CNTs, that is, one CNT with one catalytic particle encapsulated, was obtained. The results showed that copper-element doping to the Ni/Al2O3 catalyst played a key role in the synthesis of CNTs, signifying a novel approach to modify the Ni/Al2O3 catalyst. Based on the transmission electron microscopy observations, a simple growth mechanism was developed to describe the growth of the binary or triple CNTs, which could be well explained by a diffusion segregation process. [Copyright &y& Elsevier]

Abstract: The initial stage growth of bamboo-shaped carbon nanotubes (CNTs) synthesized by catalytic decomposition of methane is investigated. A special experimental procedure has been developed to stop the process after short durations (0s to 3min). It has found that during the early stages (60s), carbon cluster-encapsulated nanoparticles are formed. With prolonging synthesis time (3min), some CNTs coexisted with carbon cluster-encapsulated nanoparticles are formed. HRTEM observations show that these CNTs display multi-walled and bamboo structure and the encapsulated catalytic particles are quasi-cone morphologies. At the same time, the catalytic particles only encapsulated with carbon clusters present quasi-sphere structures. For growth up to 60min, two kinds of bamboo mode structures are observed: conical, and cylindrical, which are developed by quasi-cone and quasi-sphere catalytic particles, respectively. Moreover, the early stage growth mode of the CNTs is predominantly of the base growth mode according to TEM observations. [Copyright &y& Elsevier]

Abstract: A series of treatment processes were employed to purify and then physically activate the multi-walled carbon nanotubes obtained using catalytic decomposition of methane. In order to characterize and compare the activation effect, the carbon fibers were also treated by the same activation processes. The results showed that the normal physical activation by CO2 or steam has not too much effect on the surface area of purified multi-walled carbon nanotubes, in particular, the carbon nanotubes were burned when using the poignant activation conditions. However, the surface area of carbon fibers availably etched in the same activation processes is much increased. In addition, the mechanisms of physical activation on multi-walled carbon nanotubes and carbon fibers have been investigated. [Copyright &y& Elsevier]

Abstract: The possibility of using aluminum powder as transition metal catalyst carrier for CVD growth of carbon nanotubes (CNTs) has been investigated. The fabrication process of Ni/Al catalyst involved the production of binary colloid (Ni(OH)2/Al) by deposition–precipitation method, followed by calcination in N2 and reduction in H2. The nickel particles obtained were with uniform diameters. After the catalytic synthesis at 600°C a mass of well-graphitized multi-walled CNTs with the diameters in the 10–20nm range have been obtained, as evidenced by HRTEM. The operated catalytic particle encapsulated in CNT was nickel according to EDX analysis. However, when using pure nickel without aluminum as the catalyst, no CNTs have formed due to the agglomeration of Ni particles. Thus we speculated that the aluminum powder was responsible for the formation and the even dispersion of the nano-scale transition metal particles. [Copyright &y& Elsevier]

Abstract: Ni/Al catalysts with different Ni concentrations have been used successfully for the synthesis of carbon nanotubes and onions from methane by chemical vapor deposition. The catalyst nanoparticles were produced by a deposition–precipitation method, and the carbon products by the catalytic decomposition of methane at 600°C. Carbon nanotubes (CNTs) were formed in the presence of a Ni/Al composite catalyst containing 20wt.% nickel. The CNTs were multi-walled, 10–20nm in diameter and up to 15μm long. Hollow carbon onions were produced in the presence of a Ni/Al composite catalyst containing 80wt.% nickel. The carbon onions were from 5 to 50nm in diameter and consisted of several concentric carbon layers surrounding a hollow core. The mechanisms for the formation of both the CNTs and carbon onions were discussed on the basis of the experimental results. [Copyright &y& Elsevier]

Abstract: The synthesis of carbon nanotubes (CNTs) by chemical vapor deposition (CVD) of methane on catalyst of Ni–Cu–Al powder was reported. The influence factors on the growth morphology of CNTs, such as reaction time and different carrier gases concerning hydrogen, nitrogen as well as no carrier gas were investigated using SEM and TEM. The results showed that the reaction time brought no significant influence to the diameter of CNTs, but the average length of the CNTs was obviously increased with prolonging the reaction time. Relatively pure CNTs could be obtained with hydrogen as the carrier gas but with poor product rate compared with the CNTs with no carrier gas. Proper amount of CNTs with pure characteristic could be obtained with nitrogen as the carrier gas. Finally, a growth mechanism of section-seal is proposed for analyzing the growth process of general CNTs. [Copyright &y& Elsevier]

Highlights • A novel and efficient method to fabricate CNTs reinforced Al alloy matrix composite foams is put forward. • CNTs are homogeneously dispersed in the matrix. • The effects of CNTs on pore structure during foaming process is discussed. Abstract Uniformly dispersed carbon nanotubes (CNTs) reinforced aluminum (Al) alloy matrix composite foams were successfully fabricated by the combination of in-situ chemical vapor deposition and powder metallurgy using titanium hydride as a blowing agent. The effects of CNTs on the pore structure were systematically studied. The results showed that compared to the Al alloy foam, the introduction of CNTs could significantly improve the pore uniformity and reduce the pore size. As a result, the compressive property of composite foam had an obvious increase. The reasons for the enhanced pore structure mainly lie in that the CNTs increased nucleation sites for the decomposed hydrogen and the limited the movements of bubbles in the melt during foaming process. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nanotubes (CNTs) with diverse structures (tubular and herringbone) reinforced Al matrix composites were fabricated by a combination of in situ growth process of CNTs in Al powders and powder metallurgy (PM) process. The enhancement efficiency of CNTs with different structures and the interfacial phenomenon between CNTs and Al matrix were investigated. The results showed that herringbone CNTs with more defects reacted with Al matrix slightly and a thin intermediate layer (Al4C3) of about 1–4nm was formed between herringbone CNTs and Al matrix. Nevertheless, the interface between tubular CNTs and Al matrix was close-knit and no obvious transition layer (new phase) was found. The mechanical performance of the composites indicated that the enhancement efficiency of herringbone CNTs in Al matrix composites was lower than that of tubular CNTs, due to the formation of the brittle intermediate layer of Al4C3, implying that tubular CNTs should be more suitable to reinforce Al matrix composite. [Copyright &y& Elsevier]

Abstract: Uniform and small Fe3O4 nanocrystals (∼9nm) encapsulated in interconnected carbon nanospheres (∼60nm) for a high-rate Li-ion battery anode have been fabricated by a one-step hydrothermal process followed by annealing under Ar, which can be applied for the preparation of a number of metal oxide nanocrystals encapsulated in interconnected carbon nanospheres. The as-synthesized interconnected Fe3O4@C nanospheres displayed high performance as an anode material for Li-ion battery, such as high reversible lithium storage capacity (784mAh/g at 1 C after 50 cycles), high Coulombic efficiency (∼99%), excellent cycling stability, and superior rate capability (568mAh/g at 5 C and 379mAh/g at 10 C) by virtue of their unique structure: the nanosized Fe3O4 nanocrystals encapsulated in interconnected conductive carbon nanospheres not only endow large quantity of accessible active sites for lithium ion insertion as well as good conductivity and short diffusion length for lithium ion transport but also can effectively circumvent the volume expansion/contraction associated with lithium insertion/extraction. [Copyright &y& Elsevier]

Abstract: Fe(OH)3/Al with different Fe contents was prepared using a new deposition–precipitation reaction. Then mixed oxides were obtained by calcination of these precursors, and their catalytic activities were examined during synthesis of various carbon nanostructures. It was found that carbon nanotubes were synthesized using a Fe/Al2O3 catalyst with 10wt% Fe, while carbon coated metal nanoparticles resulted from Fe/Al2O3 catalyst with 15wt% Fe, but for the Fe/Al2O3 catalyst with 5wt% Fe, only amorphous carbon has been obtained. [Copyright &y& Elsevier]

Abstract: A facile method was proposed to use Ni/Al2O3 as a catalyst to produce metallic nickel filled carbon nanotubes. Multi-walled carbon nanotubes filled with long continuous nickel nanowire length were synthesized through chemical vapor deposition at low temperature (600°C). Furthermore, the multi-walled carbon nanotubes were well-graphitized nanotubes. The analysis of scanning electron microscopy, transmission electron microscopy, selected area electron diffraction and X-ray diffraction revealed that the metallic nickel nanowires encapsulated inside carbon nanotubes existed as a single crystalline with fcc structure. [Copyright &y& Elsevier]

Abstract: A mass of carbon-coated cobalt nanoparticles were successfully synthesized by chemical vapor deposition of methane over Co/Al catalyst at 650°C. The phases found in the as-prepared carbon-coated nanoparticles were fcc-Co. The diameter of these nanoparticles with 2–10nm carbon coating shell was in the range of 5–80nm. However, it is well-known that the Co nanoparticles are suitable for carbon nanotube synthesis, such as Co/Al2O3 and Co/SiO2 catalysts. Here, we speculated that the formation mechanism of carbon-coated cobalt nanoparticles might due to that the formation of carbon nanotubes was inhibited by the catalyst supporter of Al. Compared with Al2O3 and SiO2, Al possesses very low melting point (660°C), very high diffusion coefficient and thermal conductivity, thus the isotropic precipitation of carbon species on the surface of cobalt particles took place, favoring the formation of carbon-coated Co nanoparticles. [Copyright &y& Elsevier]

Abstract: A mass of carbon nanotubes with straight and short bodies was produced by chemical vapor deposition of methane over Ni/Al2O3. Scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis were used to analyze the synthesized carbon nanotubes. The results showed that they were well-graphitized multi-walled nanotubes and had not tangled together. Their average length was several hundreds of nanometers, suitable for their use as a nanometer-scale material. [Copyright &y& Elsevier]

Abstract: Changes in the thermogravimetrically determined oxidation behaviors of CVD-grown multi-walled carbon nanotubes (MWNTs) over Ni/Al catalyst with different Ni content were examined. Catalyst type was found to have a measurable impact upon nanotube stability, suggesting differing levels of crystalline perfection in the resulting nanotubes. With increasing the Ni content in the Ni/Al catalyst, the CNTs obtained became less stable during heat treatment in air. Furthermore, high-resolution transmission electron microscopy was employed to investigate the defect sites of as-grown MWNTs. The results provide evidence showing that defect sites along the walls and at the ends of the raw MWNTs facilitate the thermal oxidative destruction of the nanotubes. [Copyright &y& Elsevier]

Abstract: Straight carbon nanotubes, carbon onions and two kinds of herringbone carbon nanofibers have been synthesized over nickel supported on aluminum matrix by catalytic decomposition of methane. Nickel precipitated on the aluminum matrix was used as catalyst, which only had 5wt.% nickel. Through varying the production parameters such as the carrier gas, reaction temperature and reaction time, various morphologies of nanocarbons were obtained, which will be employed to reinforce aluminum matrix composites and thus the aluminum matrix composites obtained will have different potential applications. [Copyright &y& Elsevier]

Developing high-capacity anodes with fast kinetics and stable structure is critical for the effective implementation of sodium ion capacitors (SICs). In this study, Fe 2 O 3 @C nanoparticles modified vertically aligned carbon nanotubes (VACNTs) composites are designed and employed as SIC anodes through a two-step chemical vapor deposition (CVD) process with the aid of a refined Fe 3 O 4 /AlO x dispersion catalyst. With nano-sized Fe 2 O 3 coated with defected carbon layers sufficiently loading onto the VACNTs substrates, the resulting composites demonstrate remarkable sodium storage properties, with a high areal specific capacity (1.26 mAh cm−2 at 0.2 mA cm−2) and rate performance (0.19 mAh cm−2 at 5.0 mA cm−2). Moreover, continuous capacity promotion is observed over 1000 cycles, leading to superior cycling performance (0.444 mAh cm−2 at 1 mA cm−2), with 178% retention after 1000 cycles. This improved cycling performance is attributed to the defective structure and high specific surface area of the VACNTs, which accommodates the volume change of the Fe 2 O 3 particles. In addition, the induced locally graphitization and rearrangement of the carbon layers are demonstrated, which results in better kinetics for Na+ transfer, further enhancing capacity retention over long cycles. [Display omitted] • Fe 2 O 3 @C/VACNTs composites realized superior synergistic effect. • Sustained increasing for capacities were obtained by modifying nano-sized Fe 2 O 3 @C. • Refined Fe 2 O 3 paritcles and Na + insertion inducing graphtization was investigated. [ABSTRACT FROM AUTHOR]

In this paper, high strain rate dynamic compressive properties of the CNT/Al composite foams reinforced by in-situ grown carbon nanotubes (CNTs) have been investigated. The results show that the compressive strength and energy absorption capacity of the CNT/Al composite foams not only increase with the increment of CNT content but also increase with the strain rate increasing, revealing a typical strain rate sensitivity. For the 3.0 wt%-CNT/Al composite foams, the peak stress at 2130 s −1 is 52.5 MPa, which is ~ 86% higher than that at 0.001 s −1 (28.2 MPa). Besides, the deformation behavior of the pure Al foam can be significantly affected by the CNT addition and the strain rate. The different deformation behavior of the pure Al foam and composite foams is closely associated with the microstructure of pore walls. For the pure Al foam under the quasi-static condition, it can be recognised as firstly forms localized deformation bands, followed by the collapse of multi-layer deformation bands. While the failure of the CNT/Al composite foams mainly belongs to the shear deformation. In addition, as the strain rate increases from 0.001 to 800 s −1 , the deformation way of the pure Al foam transits from the local failure to layers of collapsing. Whereas, the CNT/Al composite foams still manifest as the formation of shear bands. Moreover, the pore fracture, collapsing and friction, as well as the crack propagation during the compressive processes are all beneficial to the energy absorption enhancement of the CNT/Al composite foams. [ABSTRACT FROM AUTHOR]

Silica (SiO 2 ) is regarded as one of the most promising anode materials for lithium ion batteries owing to its high theoretical specific capacity, relatively low operation potentials, abundance, environmental benignity and low cost. However, the low intrinsic electrical conductivity and large volume change of SiO 2 during the discharge/charge cycles usually results in poor electrochemical performance. In this work, carbon nanotubes (CNTs) modified SiO 2 /C composites have been fabricated through an in-situ chemical vapor deposition method. The results show that the electrical conductivity of the SiO 2 /C/CNTs is visibly enhanced through a robust connection between the CNTs and SiO 2 /C particles. Compared with the pristine SiO 2 and SiO 2 /C composites, the SiO 2 /C/CNTs composites display a high initial capacity of 1267.2 mA h g −1 . Besides, an excellent cycling stability with the capacity of 315.7 mA h g −1 is achieved after 1000th cycles at a rate of 1 A g −1 . The significantly improved electrochemical properties of the SiO 2 /C/CNTs composites are mainly attributed to the formation of three dimensional CNT networks in the SiO 2 /C substrate, which can not only shorten the Li-ion diffusion path but also relieve the volume change during the lithium-ion insertion/extraction processes. [ABSTRACT FROM AUTHOR]

This work presents an in-situ chemical vapor deposition (CVD) method to synthesis carbon nanotube (CNT) on Al powders in a vertical tube furnace. The carbon nanotube reinforced Al matrix composites (CNT/Al composites) were fabricated by a new powder metallurgy (PM) approach associated with vacuum induction melting technique. It was shown that CNT was homogenously distributed in the Al matrix, and an interfacial transiting layer of Al 4 C 3 was formed between Al matrix and CNT in the bulk material. The tensile test showed that 1.5 vol% CNT/Al composites exhibited the largest tensile strength of 191 MPa as well as an excellent elongation of 32.6%. The strengthening efficiency of the 1.5 vol% CNT/Al composites improved by ~ 80% compared to the unreinforced pure Al. The strengthening mechanisms were mainly attributed to the load transfer of CNT, Al 4 C 3 and dislocation strengthening. The Al 4 C 3 transiting layer was beneficial to increase the interfacial shear strength and prolong the slide deformation of dislocation by forming an orientation relationship of Al 4 C 3 <001> // Al <111> and CNT (002) // Al 4 C 3 (001) according to the transmission electron microscope (TEM) observation. Besides, the thermocycling measurement enriched and deepened the understanding of the effect of Al 4 C 3 on improving the interfacial bonding, degrading the interfacial thermal mismatch between CNT and the Al matrix and increasing the compactness of the CNT/Al composites. [ABSTRACT FROM AUTHOR]

With the assistance of soluble salt template, we designed and synthesized a Sn-core/CNT-shell nanocable anchored interconnected carbon networks structure via a simple CVD process. The Sn nanorods with a diameter of ∼50 nm are protected by ∼3 nm CNTs. The whole hierarchical structure forms a conductive network, which ensures rapid transportation of electrons. As a result, when utilized as lithium-ion battery anode, the 3DC-Sn@CNT electrode exhibits good cycling stability (700 mAh g −1 after 100 cycles at 0.1 A g −1 ) and rate performance (240 mAh g −1 at 1 A g −1 ). [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT) reinforced Al composite foams were successfully fabricated by the combination of an in-situ chemical vapor deposition (CVD), short-time ball-milling and space-holder method. The CNTs are homogeneously dispersed and embedded in the Al foam matrix after 90 min ball-milling while maintaining the structural integrity. Both compressive properties and energy absorption capacity of the composite foams increase with the increment of CNT content but decrease with the temperature rising between 25 and 250 °C. The compressive yield strength and the plateau stress of 3.0 wt%-CNT/Al composite foams maintain 16.8 and 20.2 MPa at 150 °C, respectively, which are much higher than the corresponding yield stress (5.7 MPa) and plateau stress (8.6 MPa) of the pure Al foam. Especially, the energy absorption capacity of the 3.0 wt%-CNT/Al composite foams reaches 19.8 MJ/m 3 at 150 °C, which is ~2.5 times higher than that of pure Al foam. Fracture analysis shows that the failure mode of the Al foam changes from ductile type to brittle type combined with ductile type, as a result of the CNT addition in the matrix. [ABSTRACT FROM AUTHOR]

Evading the strength-ductility trade-off is essential for engineering application of metal matrix composites. Herein, we propose a novel strategy to achieve the prominent strength-ductility combination of nanocarbon-Al composites. The strategy makes use of the nanocarbon architecture design via longitudinally unfolding the multi-walled carbon nanotubes (CNTs) into graphene nanoribbons (GNRs). It was found that the nano-sized intragranular and interfacial Al 4 C 3 (length: 64±23 nm) easily formed in GNR/Al via the "heterogeneous nucleation-growth" pattern, which is contrary to the submicron-sized epitaxial Al 4 C 3 (length: 133±39 nm) in CNT/Al. Detailed characterizations reveal the specific orientation relationships between Al 4 C 3 and Al in GNR/Al, which benefits the robust interfacial bonding. The intragranular Al 4 C 3 and intergranular GNR with large aspect ratio effectively increase the dislocation storage and hence working hardening ability, which leads to the strength-ductility synergy of GNR/Al. Meanwhile, the GNR anchored by dense interfacial Al 4 C 3 introduces extra toughening effect by crack bridging, blunting and deflection. [Display omitted] [ABSTRACT FROM AUTHOR]

This research demonstrates a flexible one-pot strategy for fabricating three-dimensional (3D) boron/nitrogen-doped networks of carbon nanotubes(CNTs)/carbon nanosheets “Line-in-Wall” hybrids (LIW-NB) based on the space-confined template method. In the synthesis, the high rate of freezing step and freeze-dried process enable the CNTs and carbon-heteroatoms sources confined in the limited space of the self-assembled NaCl salts, which are then heat-treated to obtain a B/N-doped network constructed by “Line-in-Wall” type of carbon hybrids. By combining the 3D B/N-doped carbon nanosheets network and CNTs in this unique pattern, the LIW-NB integrates advantages of three aspects: first, the doped heteroatoms enhancing electrochemical properties of carbon matrix; second, the warp-proof nanosheets supplying high specific surface area; and the extracted and embedded CNTs serving as electron conductive paths and reinforcing the whole architecture. As a result, the 3D LIW-NB shows excellent electrochemical properties: as the electrode of supercapacitors, LIW-NB exhibits high specific capacity at different current densities (389 F g −1 at 1 A g −1 and 129 F g −1 at 20 A g −1 ); as the lithium ion battery anode, it possesses high reversible storage capacity (1165 mAh g −1 at 0.1 A g −1 ) and stable long cycle performance at high rate (1000 cycles at 2 A g −1 ). [ABSTRACT FROM AUTHOR]

A SiO 2 /porous carbon nanocomposite was synthesized by a facile combined heat and acid treatments method. The nanocomposite featured a 3D porous carbon structure with amorphous SiO 2 nanoparticles embedded in the wall of the pores. The microstructure improved the electrical conductivity, shortened the diffusion distance of lithium ions, and alleviated the volume expansion of SiO 2 during Li intercalation. Accordingly, the SiO 2 /porous carbon nanocomposite displayed excellent cyclic performance with a high reversible capacity of 434 mAh g −1 after 50 cycles at 0.1 A g −1 and rate capability delivering a capacity of 187.4 mAh g −1 even at 5 A g −1 . [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT) reinforced Al matrix composites were produced by a modified powder metallurgy route, including in-situ synthesis of CNTs on Al powders by chemical vapor deposition and subsequent ball-milling process. The influence of CNT content (0–4.5 wt%) on the microstructure, mechanical and coefficient of thermal expansion (CTE) performance of CNT/Al composites was systematicly investigated. During the fabrication process, well dispersed CNTs with integrated structure are deeply embedded in Al matrix to form an effective interface bonding. The hardness and tensile strength of CNT/Al composites monotonically increase with the increment of CNT content. The 4.5 wt%-CNT/Al composites exhibit largest hardness and tensile strength, which is 2.3 and 2.4 times higher than that of starting Al, respectively. The CTEs of the composites decrease with the increase of CNT content at the temperature range of 100–300 °C. The CTE of the 4.5 wt%-CNT/Al composites reduces as much as 17% compared with that of starting Al at 100 °C. Thus, we offer a large variety of mechanical and CTE properties which depend on the CNT content in CNT/Al composites, all of them might be good alternatives depending on the application purpose. [ABSTRACT FROM AUTHOR]

The effects of alloying elements (Mg, Zn, Cu, Sc and Ti) on the interfacial bonding between a carbon nanotube (CNT) and an Al(111) surface are studied systematically using first-principles total energy calculations. The redistribution of the charge density of the Al(111) surfaces induced by the five alloying elements, the projected densities of state, and the crystal orbital Hamilton population analysis of the atomic pairs in the vicinity of the interface are analyzed in detail. Thereby, it is revealed that the bonding characteristic between the CNT and the Al(111) surfaces are modified when alloying with the early transition metals Sc and Ti that occupy subsurface positions. Also for the other alloying elements a weak interaction between CNT and the substrates is found although these elements occupy surface positions in the Al(111) surface. Through a detailed study of the interaction potential energy and the restructuring energy, we demonstrate that different mechanisms are responsible for the substrate–CNT interactions. [ABSTRACT FROM AUTHOR]

In-situ synthesized carbon nanotubes (CNTs) reinforced aluminum–copper (Al–Cu) composites have been prepared by powder metallurgy. The strengthening effect of CNTs reinforcement and precipitation hardening of Al–Cu matrix has been investigated. CNTs and Cu nanoparticles are homogeneously embedded into Al powders through the process of in-situ preparation and ball milling. XRD results show that Cu elemental phase is converted to Al 2 Cu phase during the procedure of sintering. Raman spectra indicate that CNTs could maintain its structural integrity during powder metallurgy. In T6 heat treatment, the aging time of peak hardness has been reduced from 9 h to 3 h, demonstrating accelerated aging of the composite. Besides, the ultimate tensile strength of CNTs/Al–Cu composites have a 33.9% increase compared with that of Al–Cu alloy, and a further increase could be achieved (20.3%) after T6 heat treatment. The strengthening mechanism of CNTs/Al–Cu composites combines two synergistic factors: CNTs reinforcement and precipitation hardening of Al–Cu alloy. [ABSTRACT FROM AUTHOR]

Highlights: [•] Using zwitterionic surfactant to enhance the dispersion of the CNTs on the powder surface. [•] CNTs as carbon source decreased the formation temperature of Ti2AlC. [•] Al2O3 was generated in situ from the oxygen atoms introduced in the drying procedure. [•] Nanosized Ti3Al was precipitated at 1250°C and distribute in the TiAl matrix homogeneously. [•] Ti2AlC–Al2O3/TiAl composite was synthesized in situ by sintering pre-alloy Ti–Al coated with CNTs. [ABSTRACT FROM AUTHOR]

Abstract: An approach was developed to fabricate carbon nanotube (CNT)-reinforced Al composites. In a typical process, the Co catalyst was evenly deposited on the surface of Al powder by impregnation route, and then the CNTs were grown in the Al powder by chemical vapor deposition to obtain CNT/Al powders. After ball-milling of the obtained powders for a short time, the CNT/Al composites were fabricated by compacting, sintering and hot extrusion of the ball-milled powders. During this process, the well dispersed CNT reinforcement is deeply embedded in the Al powder forming an effective interface bonding with matrix. As a result, the CNT/Al composites containing 2.5wt.% CNTs exhibit the ultimate tensile strength of 334MPa which is 1.7 times higher than that of unreinforced Al, and good ductility of ∼18% elongation to failure. Thus, well-balanced strength and ductility are achieved in CNT-reinforced Al composites. [Copyright &y& Elsevier]

Abstract: In this paper, carbon nanotubes (CNTs) are added in order to investigate their influence on the electronic conductivity of LiFePO4 cathode. CNTs/LiFePO4 composites are prepared by in-situ chemical vapor deposition method and the traditional mechanical mixture method respectively in order to investigate the influence of CNTs as an additive on the electrochemical performance of LiFePO4 cathode. The particle morphology and electrochemical performances of the CNTs/LiFePO4 composites are characterized and compared with commercial cathodes, LiFePO4 mixed with carbon black. The in-situ synthesized CNTs/LiFePO4 composite by chemical vapor deposition method maintains full retaining ratio after 100 cycles at 1C and 94.5% retention after 20 cycles at 10C, which precede the CNTs/LiFePO4 composite fabricated by the mechanical mixture method as well as the commercial cathode. The enhanced electrochemical performance is due to the excellent interface bonding between LiFePO4 and CNT in in-situ synthesized CNTs/LiFePO4 composites. The interface benefits the electronic conductivity of the composites, as well as the polarization reduction. [Copyright &y& Elsevier]

Abstract: It is well known that Fe, Co, Ni, and their alloy are the effective catalyst components in chemical vapor deposition growth of carbon nanotubes (CNTs), while Cu has low catalytic activity owing to its nearly zero carbon solubility. In this paper, a simple and effective approach was developed to synthesize multi-walled CNTs using unmodified Cu catalyst supported on Al matrix under a low temperature (600°C). The obtained CNTs with bamboo-like structure are mainly composed of well-crystallized graphite. It is found that the Al carrier plays a key role in the catalytic growth of CNTs, signifying a new way for low-temperature synthesis of multi-walled CNTs. [Copyright &y& Elsevier]

Abstract: 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 &y& Elsevier]

Abstract: Multi-walled carbon nanotubes (CNTs), which are with the diameter from 15 to 50 nm and length from several microns to several tens of microns, were synthesized over Ni/Al composite catalyst by CVD of methane at the temperature range of 723 K–923 K. The Ni content in the Ni/Al composite catalyst varied from 5 wt.% to 15 wt.%. As the synthesis temperature increased from 723 K to 923 K and the nickel content increased from 5 wt.% to 15 wt.%, the CNT yield increased by about 17 times. The purity of CNTs decreased and the diameter of CNTs increased with the increase of Ni content in the catalyst. The relative amount of crystalline graphite sheets increased progressively with the growth temperature and a higher degree of crystalline perfection could be achieved at 923 K. These results demonstrated that the growth rate, diameter, and crystallinity of CNTs can be controlled by varying the synthesis temperature and catalyst composition. [Copyright &y& Elsevier]

Metal oxide/carbon materials composites (MOx/C) are broadly used as electrodes in energy storage devices. However, their capacity under high rates is limited due to the sluggish ion/electron transportation during faradaic reactions. In this work, carbon nanotube carpets (CC)/Fe 2 O 3 nanoparticles covered with bud-liked carbon layer (CC/Fe 2 O 3 @b-C) is developed as an electrode by interfaces design. It is found that the bud-liked carbon wrapper enlarges interface area and provides an accelerated conducting network between CC and Fe 2 O 3 nanoparticles through "seamless" connection. With boosted charge transfer efficiency, this composite demonstrates an excellent rate capability. The CC/Fe 2 O 3 @b-C electrode shows a high capacity of 246.15 mC cm−2 under 5 mV s−1 and can maintain ~95% when the scan rate is increased to 100 mV s−1. Moreover, the hybrid device paired with carbon fiber cloth (CFC)/Co(OH) 2 cathode exhibits simultaneous high energy density and power density, showing good potential application in high-power devices. Image 1 • Bud-liked CNT carpets/Fe 2 O 3 @C were seamlessly connected through interfaces control. • Boosted charge transfer efficiency was obtained by perfectly matching R s and R ct. • Principles of designing MOx/C composites for energy storage devices were concluded. [ABSTRACT FROM AUTHOR]

Abstract: TiO2 nanoparticles are widely used in dye-sensitized solar cells (DSSCs). The combination of one-dimensional materials such as carbon nanotubes (CNTs) with TiO2 nanocrystals by mechanical mixing has been expected to improve the electron transport of anode. However, these methods cannot ensure the connection between one-dimensional materials and collector, which is the key for exerting the fast electron transport property. In this study, a novel synthesis method named gel chapping for CNTs/TiO2 nanocomposites preparation is presented, in which porous nanocrystalline TiO2 film with through-hole cracks is fabricated. By using the porous films with cracks as templates, CNTs are deposited in pores and well connected with the template and current collector which favors the transportation of electrons. The current–voltage curve test reveals that the conversion efficiency of CNTs/TiO2 nanocrystalline composite structures is 2.6 times superior to TiO2 nanocrystalline film. [Copyright &y& Elsevier]