A three-dimensional cross-linked porous silver network (PSN) is fabricated by silver mirror reaction using polymer foam as the template. The N-doped porous carbon nanofibers (N-PCNFs) are further prepared on PSN by chemical vapor deposition and treated by ammonia gas subsequently. The PSN substrate serving as the inner current collector will improve the electron transport efficiency significantly. The ammonia gas can not only introduce nitrogen doping into PCNFs but also increase the specific surface area of PCNFs at the same time. Because of its large surface area (801 m2/g), high electrical conductivity (211 S/cm), and robust structure, the as-constructed N-PCNFs/PSN demonstrates a specific capacitance of 222 F/g at the current density of 100 A/g with a superior rate capability of 90.8% of its initial capacitance ranging from 1 to 100 A/g while applied as the supercapacitor electrode. The symmetric supercapacitor device based on N-PCNFs/PSN displays an energy density of 8.5 W h/kg with power density of 250 W/kg and excellent cycling stability, which attains 103% capacitance retention after 10 000 charge–discharge cycles at a high current density of 20 A/g, which indicates that N-PCNFs/PSN is a promising candidate for supercapacitor electrode materials.Keywords: chemical vapor deposition; high rate; N-doped; porous carbon nanofibers; porous silver network; silver mirror reaction; supercapacitor;

Free-standing robust three-dimensional (3D) rebar graphene foams (GFs) were developed by a powder metallurgy template method with multiwalled carbon nanotubes (MWCNTs) as a reinforcing bar, sintered Ni skeletons as a template and catalyst, and sucrose as a solid carbon source. As a reinforcement and bridge between different graphene sheets and carbon shells, MWCNTs improved the thermostability, storage modulus (290.1 kPa) and conductivity (21.82 S cm–1) of 3D GF resulting in a high porosity and structurally stable 3D rebar GF. The 3D rebar GF can support >3150× the foam’s weight with no irreversible height change, and shows only a ∼25% irreversible height change after loading >8500× the foam’s weight. The 3D rebar GF also shows stable performance as a highly porous electrode in lithium ion capacitors (LICs) with an energy density of 32 Wh kg–1. After 500 cycles of testing at a high current density of 6.50 mA cm–2, the LIC shows 78% energy density retention. These properties indicate promising applications with 3D rebar GFs in devices requiring stable mechanical and electrochemical properties.Keywords: dynamic mechanical analysis; lithium ion capacitor; powder metallurgy; rebar graphene; three-dimensional;

•A thermal decomposition-reduction method was developed to prepare NDG/MoS2/NDG.•The MoS2 is fully coated by NDG nanosheets in NDG/MoS2/NDG heterostructure.•The NDG coating layer can effectively solve the polysulfide shuttling problem.•The NDG/MoS2/NDG exhibits a high initial CE and a high-rate long-life cycling capability.Integrating MoS2 with various carbonaceous matrices, especially graphene, has been extensively explored for lithium-ion storage. However, mostly reported MoS2/graphene/MoS2 nanostructures have been suffering from their low yield, costly and time-consuming prepared methods as well as their polysulfide shuttling problem owing to a certain degree of adverse reaction to the electrolyte. Herein, layer-by-layer nitrogen-doped graphene/MoS2/nitrogen-doped graphene (NDG/MoS2/NDG) stacking heterostructure has been prepared through a scalable and low-cost in-situ thermal decomposition-reduction method. This new NDG/MoS2/NDG exhibits high crystallization degree MoS2, intimate interface contacts and fully NDG coating, which can effective host the electrochemical products of Mo and soluble lithium polysulfide and restrain the adverse reaction to the electrolyte. As a result, it shows a high initial CE (84.3%), excellent high-rate cycle performance (552 mAh g−1 at 1 A g−1 after 600 cycles) and a high areal capacity (409 mAh g−1 at 8.73 mg cm−2) when evaluated as lithium-ion batteries (LIBs) anode. Moreover, we have systematically studied the Li-storage mechanism, which confirms that the NDG coating layer shows significantly effect and advantage on solving polysulfide shuttling problem. We believe that this work can open up an avenue for the rational design of various anode materials, such as NDG coated metal oxides and sulfides for high performance LIBs and other energy related field.A facile and scalable thermal decomposition-reduction method was developed to synthesize layer-by-layer NDG/MoS2/NDG composites, which shows high crystalline MoS2, intimate interface contacts and fully NDG coating. These advantages result in superior structure stability, electron and Li-ion transport properties, and finally leading to a high initial CE, a high capacity at high area mass loading, and excellent cycle performance at high rate.Download high-res image (452KB)Download full-size image

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.

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/m3 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.

•Adding Sc and Zr changed the cross section morphology of inter-granular corrosion.•There exists a corrosion mechanism conversion of S precipitates in Al-Cu-Mg alloy.•Adding Sc and Zr restricted the corrosion mechanism conversion of S particles.•The Al-Cu-Mg-Sc-Zr alloy possesses excellent inter-granular corrosion properties.•The content of Cu and Mg elements decreased along the grain boundary after minor Sc and Zr addition.The effects of adding the alloy element Sc to Al alloys on strengthening, recrystallization and modification of the grain microstructure have been investigated. The combination of Sc and Zr alloying not only produces a remarkable synergistic effect of inhibition of recrystallization and refinement of grain size but also substantially reduce the amount of high-cost additional Sc. In this work, the microstructures and corrosion behavior of a new type of Al-Cu-Mg-Sc-Zr alloy with Sc/Zr ratio of 1/2 were investigated. The experimental results showed that the Sc and Zr additions to Al-Cu-Mg alloy could strongly inhibit recrystallization, refine grain size, impede the segregation of Cu element along the grain boundary and increase the spacing of grain boundary precipitates. In addition, adding Sc and Zr to Al-Cu-Mg alloy effectively restricts the corrosion mechanism conversion associated with Al2CuMg particles, which resulted in the change of the cross-section morphology of inter-granular corrosion from an undercutting to an elliptical shape. The susceptibility to inter-granular corrosion was significantly decreased with increasing Sc and Zr additions to the Al-Cu-Mg alloy. The relationships between microstructures evolution and inter-granular corrosion mechanism of Al-Cu-Mg-Sc-Zr alloys were also discussed.Download high-res image (220KB)Download full-size image

It is a tough issue to design and fabricate discontinuously reinforced metal matrix composites (DRMMCs) with desired mechanical and physical properties. Utilizing nanocarbon materials such as one-dimensional (1D) carbon nanotubes (CNTs), two-dimensional (2D) graphene or their hybrids as reinforcements for DRMMCs is now considered to be a good solution because of their outstanding intrinsic characterizations. In this work, we proposed a novel in-situ space-confined strategy to circumvent the problem of the controllable interconnection and bonding between CNTs and graphene and thus constructed a well-dispersed CNTs embedded in three-dimensional graphene network (3D GN) hybrid structure for fabricating reinforced Cu matrix nanocomposites. The as-obtained 3D GN/CNT hybrids reinforced copper bulk nanocomposites exhibited a significant strengthening efficiency and a more balanced strength vs. ductility relation compared with Cu matrix composites reinforced by single component (CNT or 3D GN) with the same volume fraction.

•The chemical role of the intermediate O between Cu and graphene is revealed.•Interaction between Cu and B- and N-doped graphene with integrity are studied.•B doping effect is comparable to or even better than the intermediate oxygen.•B doping enhances the mechanical properties of graphene/Cu composite.In order to explore an efficient way of modifying graphene to improve the Cu/graphene interfacial bonding and remain the excellent mechanical and physical properties of graphene, the interaction between Cu and the pristine, atomic oxygen functionalized and boron- or nitrogen-doped graphene with and without defects was systematically investigated by density functional theory calculation. The electronic structure analysis revealed that the chemically active oxygen can enhance the binding energy Eb of Cu with graphene by forming strong covalent bonds, supporting the experimental study suggesting an vital role of intermediate oxygen in the improvement of the mechanical properties of graphene/Cu composites. Due to the strong hybridization between Cu-3d electron states and the 2p states of both boron and carbon atoms, the boron-doping effect is comparable to or even better than the chemical bridging role of oxygen in the reduced graphene oxide reinforced Cu matrix composite. Furthermore, we evidenced an enhancement of mechanical properties including bulk modulus, shear modulus and Young modulus of graphene/Cu composite after boron doping, which closely relates to the increased interfacial binding energy between boron-doped graphene and Cu surfaces.Download high-res image (130KB)Download full-size image

Graphene or graphene-like nanosheets have been emerging as an attractive reinforcement for composites due to their unique mechanical and electrical properties as well as their fascinating two-dimensional structure. It is a great challenge to efficiently and homogeneously disperse them within a metal matrix for achieving metal matrix composites with excellent mechanical and physical performance. In this work, we have developed an innovative in situ processing strategy for the fabrication of metal matrix composites reinforced with a discontinuous 3D graphene-like network (3D GN). The processing route involves the in situ synthesis of the encapsulation structure of 3D GN powders tightly anchored with Cu nanoparticles (NPs) (3D GN@Cu) to ensure mixing at the molecular level between graphene-like nanosheets and metal, coating of Cu on the 3D GN@Cu (3D GN@Cu@Cu), and consolidation of the 3D GN@Cu@Cu powders. This process can produce GN/Cu composites on a large scale, in which the in situ synthesized 3D GN not only maintains the perfect 3D network structure within the composites, but also has robust interfacial bonding with the metal matrix. As a consequence, the as-obtained 3D GN/Cu composites exhibit exceptionally high strength and superior ductility (the uniform and total elongation to failure of the composite are even much higher than the unreinforced Cu matrix). To the best of our knowledge, this work is the first report validating that a discontinuous 3D graphene-like network can simultaneously remarkably enhance the strength and ductility of the metal matrix.

In order to improve the electrical conductivity of metal–organic frameworks (MOFs) which have drawn remarkable attention owing to their potential application in the energy storage field, a Co-based zeolitic imidazolate framework (ZIF-67) polyhedron was in situ integrated into a three-dimensional carbon network (3DCN) to construct a Ball-in-Cage (BIC) nanostructure. The introduced 3DCN acting as the electronic pathway can provide nucleation sites for MOF particles; consequently, further growth of the MOF particles is limited by the size effect of 3DCN. The BIC frame not only controls the MOF particle size, but also ensures a high electron conductivity of the entire structure. The as-prepared BIC electrode displays an outstanding capacitance of 119 F g−1 at a current density of 0.5 A g−1 and a great rate performance as well, which can be expected to be a promising approach to enhance the electrochemical performance of pristine MOFs in the future.

A convenient and scalable in situ chemical vapor deposition (CVD) method is developed for one-step fabrication of sandwiched graphene sheets which were filled with yolk–shell γ-Fe2O3 nanoparticles encapsulated with graphene shells (YS-γ-Fe2O3@G-GS). Such a unique architecture can be applied to produce an excellent lithium ion battery (LIB) anode. As a result, long-term cycling stability at high rates (a high capacity of 663.7 mA h g−1 is achieved at 2 A g−1 and maintained at approximately 96.6% even after 1500 cycles) and superior rate capability (1173 mA h g−1 at 0.1C, 989 mA h g−1 at 0.2C, 827 mA h g−1 at 0.5C, 737 mA h g−1 at 1C, 574 mA h g−1 at 2C, 443 mA h g−1 at 5C, and 350 mA h g−1 at 10C; 1C = 1 A g−1) can be obtained when YS-γ-Fe2O3@G-GS is used as an LIB anode. As far as we know, this is the best rate capacity and longest cycle life ever reported for an Fe2O3-based LIB anode.

Interconnected 3D graphene foams with a large number of controllable micro–mesoporous structures are promising electrode materials for supercapacitors due to their high electrical conductivity and large effective surface area. Here we successfully obtained a flexible high-quality nitrogen and oxygen co-doped 3D nanoporous duct-like graphene@carbon nano-cage film by chemical vapor deposition using nanoporous copper (NPC) as the substrate and further modifying with HNO3. The bicontinuous mesoporous architecture catalyzed by NPC retains the 2D coherent electronic properties of graphene. Carbon nano-cages grown on the surface of the 3D nanoporous graphene combined with the microporous structure caused by heteroatom-doping greatly increase the effective specific surface area. Moreover, heteroatom-doping and oxygen-containing groups on the surface of graphene can obtain extra redox capacitance and achieve good wettability between the electrode and the electrolyte. The superior structure means that NO-3DG@CNC-based multi-style supercapacitors, such as aqueous-system, ionic-system, and lithium-ion capacitors etc., all show high energy density, high power density and excellent cycling stability.

A graphene-reinforced N-doping porous carbon network is fabricated using a simple strategy for the electrodes of supercapacitors and lithium ion batteries. In this approach, sodium carbonate is dissolved with glucose and urea and then the obtained solution is coated on a metal substrate. A subsequent heating process enables the organic complex to convert into N-doping porous carbon network replicating the pattern of the salt template. Moreover, wave-like graphene is formed at the interspace between the metal and salt, which not only increases the overall electronic conductivity but also enhances structural stability for engaging the material with a free-standing feature. The heterogeneous space-confined effect of metal/salt plays a critical role in the formation of this hybrid, which is further investigated by molecular simulation. The various advantages of 2D and 3D structures endow this carbon hybrid with superior electrochemical properties; as a Li-ion battery anode, the hybrid exhibits high reversible capacity (775 mA h g−1 at 0.1 A g−1) and long cycling stability (stability is maintained after 1000 cycles at 2 A g−1); in supercapacitors, it presents high capacitive property (238 F g−1 at 1 A g−1) and, as a result, it exhibits outstanding capacitance retention (118 F g−1 at 200 A g−1).

•CNTs are homogeneously dispersed in the Al foam matrix.•High damping capacity of CNT reinforced Al composite foams.•Large numbers of well-bonded interfaces are formed between CNTs and Al foam matrix.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.

Sluggish surface reaction kinetics hinders the power density of Li-ion battery. Thus, various surface modification techniques have been applied to enhance the electronic/ionic transfer kinetics. However, it is challenging to obtain a continuous and uniform surface modification layer on the prime particles with structure integration at the interface. Instead of classic physical-adsorption/deposition techniques, we propose a novel chemical-adsorption strategy to synthesize double-shell modified lithium-rich layered cathodes with enhanced mass transfer kinetics. On the basis of experimental measurement and first-principles calculation, MoO2S2 ions are proved to joint the layered phase via chemical bonding. Specifically, the Mo–O or Mo–S bonds can flexibly rotate to bond with the cations in the layered phase, leading to the good compatibility between the thiomolybdate adsorption layer and layered cathode. Followed by annealing treatment, the lithium-excess-spinel inner shell forms under the thiomolybdate adsorption layer and functions as favorable pathways for lithium and electron. Meanwhile, the nanothick MoO3–x(SO4)x outer shell protects the transition metal from dissolution and restrains electrolyte decomposition. The double-shell modified sample delivers an enhanced discharge capacity almost twice as much as that of the unmodified one at 1 A g–1 after 100 cycles, demonstrating the superiority of the surface modification based on chemical adsorption.Keywords: chemical-adsorption; DFT calculations; double shell; lithium rich layered cathode; surface modification

High-quality microsized ultrathin single-crystalline anatase TiO2 nanosheets (MS-TiO2) with exposed {001} facets were synthesized by a facile and low-cost two-step process that combines a graphene oxide (GO)-assisted hydrothermal method with calcination. Both GO and HF play an important role in the formation of well dispersed MS-TiO2. As a novel microsized (1–4 μm) ultrathin two-dimensional (2D) material, MS-TiO2 possesses much higher lateral size and aspect ratio compared to common 2D nanosized (30–60 nm) ultrathin TiO2 nanosheets (NS-TiO2), resulting in excellent electronic conductivity and superior electron transfer and diffusion properties. Here, we fabricated MS-TiO2 and NS-TiO2, both of which were incorporated with the TiO2 nanoparticles (P25) to constitute the hybrid photoanode of dye-sensitized solar cells (DSSCs), and explored the effect of the lateral size (nano- and micro-) of ultrathin TiO2 nanosheets on their electron transfer and diffusion properties. Benefiting from the faster electron transfer rate and short diffusion path of the MS-TiO2, the MS-TiO2/P25 gains the more superior performance compared to pure P25 and NS-TiO2/P25 in the application of DSSCs. Moreover, it is expected that the novel high aspect ratio MS-TiO2 may be applied in diverse fields including photocatalysis, photodetectors, lithium-ion batteries and others concerning the environment and energy.Keywords: electron diffusion property; electron transfer property; graphene oxide; microsized; nanosized; TiO2 nanosheets; ultrathin

A flexible one-pot strategy for fabricating a 3D network of nitrogen-doped (N-doped) carbon ultrathin nanosheets with closely packed mesopores (N-MCN) via an in situ template method is reported in this research. The self-assembly soluble salts (NaCl and Na2SiO3) serve as hierarchical templates and support the formation of a 3D glucose–urea complex. The organic complex is heat-treated to obtain a 3D N-doped carbon network constructed by mesoporous nanosheets. Especially, both the mesoporous structure and doping content can be easily tuned by adjusting the ratio of raw materials. The large specific surface area and closely packed mesopores facilitate the lithium ion intercalation/deintercalation accordingly. Besides, the nitrogen content improves the lithium storage ability and capacitive properties. Due to the synergistic effect of hierarchical structure and heteroatom composition, the 3D N-MCN shows excellent characteristics as the electrode of a lithium ion battery and supercapacitor, such as ultrahigh reversible storage capacity (1222 mAh g–1 at 0.1 A g–1), stable long cycle performance at high current density (600 cycles at 2 A g–1), and high capacitive properties (225 F g–1 at 1 A g–1 and 163 F g–1 at 50 A g–1).Keywords: 3D network; in situ salt templates; lithium ion battery; mesoporous carbon nanosheets; nitrogen-doping; supercapacitor

•A three-dimensional (3D) B/N-doped carbon nanotube/carbon nanosheets “Line-in-Wall” hybrids (LIW-NB) is fabricated by the space-confine effect of salts template.•The unique nanostructure, combining the advantages of 3D nanosheets networks and the carbon nanotubes, possesses the high surface area and the structural stability.•The B/N-doping increases the capacitance and enhances the wettability of electrolyte/electrode, and provides additional active site for lithium ion storage.•LIW-NB exhibits high specific capacitance in supercapacitor and stable long cycle performance at high rate as the lithium ion battery anode.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).

•3D graphene is in-situ grown on Cu powders by using CVD for the first time.•Interfaces between in-situ 3D graphene and Cu exhibit good bonding and stable status.•3D graphene reinforces the composite by impeding the propagation of dislocations.•In-situ grown 3D graphene achieves high reinforcing efficiency in the composite.In this study, a Cu matrix composite is synthesized reinforced by an in-situ three-dimensional graphene network (3D-GN) grown through chemical vapor deposition (CVD). Nano Cu powders and polymethylmethacrylate (PMMA) are employed as matrix and carbon source respectively. PMMA is dispersed on Cu powders after ball-milling. During the CVD process, carbon atoms from pyrolyzed PMMA diffuse and precipitate on Cu powders. By inheriting the morphology of Cu powders, carbon atoms build a 3D-GN in-situ on Cu powders. A bulk 3D graphene/composite with 0.5 wt% graphene is obtained by vacuum hot-press sintering. The favorable interfaces that crucial to the achievement of exceptional mechanical properties of a bulk composite are verified by TEM and SEM characterizations. A yield strength and tensile strength of 290 MPa and 308 MPa respectively are achieved of the composite. The structure of 3D-GN is well preserved in the bulk composite. We demonstrate that the 3D-GN serves as an effective obstacle to the propagation of dislocations by TEM further.

•We report a novel and easy method using the silver mirror reaction to obtain ultralight monolithic silver foams.•The cheap melamine resin foam was used to synthesize the ultralight metal foams for the first time.•The ultralight silver foams have remarkably low densities down to 18.7 mg/cm3 or 99.8% porosity.•The densification strain of the silver foam can reach 80% because of the ultralow densityIn this study, ultralight monolithic silver foams were synthesized by a novel and easy method based on the traditional silver mirror reaction. The resultant silver foams had remarkably low densities down to 18.7 mg/cm3 or 99.8% porosity. The compression properties were measured and the present ultralight silver foams showed a similar stress–strain behavior compared with the other metallic foams. The densification strain of the silver foam can reach 80% because of the ultralow density. The compressive stress increased with increasing relative density.

A systematic study on heterogeneous nucleation, microstructure and mechanical properties of A357-0.033Sr alloys with different Ti/Sc atom ratio was carried out. According to the obtained results, a Ti/Sc atom ratio up to 1:1 did not show much change in the heterogeneous nuclei but at a higher atom ratio level, heterogeneous nuclei have a great change in chemical composition and morphology (from strip Ti-rich phase to the particle-like Ti-rich phase). In addition, compared to the other four alloys studied, the A357-0.033Sr-0.30Sc-0.35Ti alloy with 1:1 atom ratio has the smallest grain size (88 µm), optimum microstructure (morphology, size and distribution of eutectic Si), densest core-shell Al3(Sc, Ti), all of which result in the best mechanical properties. Its tensile strength and elongation reach 287 MPa and 3.62% respectively, showing about 11% and 84% increases compared with A357-0.033Sr alloy.

•The mechanism for the growth of MoS2 onto the surface of TiO2 is first demonstrated.•Both rich defects and intimate interfaces contribute to excellent performance.•The synergistic effect between rich defects and interfaces is first revealed.•The UT-TiO2/C@DR-MoS2 anodes enable brilliant cycling stability and rate capacity.Poor cycling performance and rate capability are the major barriers to the application of layered transition-metal sulfide as the next generation anodes materials for lithium-ion batteries (LIBs). In this paper, a smart composite consisting of defect-rich MoS2/carbon-coated ultrathin TiO2/defect-rich MoS2 sandwich-like nanosheets has been constructed to enhance the cycling and rate performances of MoS2. In this uniform sandwich-like structure, carbon-coated ultrathin TiO2 is conformably embedded by defect-rich MoS2 shells via intimate interfacial contacts, while the carbon coats TiO2via Ti–O–C bonds. It is first revealed that the synergistic effect between rich defect in few-layer MoS2 nanosheets and abundant interfaces in the composites, as well as the high structure stability of TiO2 during discharge and charge process, results in excellent performance of the composites as LIBs anode materials. These LIBs anodes achieve the best rate capability (785.9, 507.6 and 792.3 mA h g−1 at 0.1, 2 and 0.1 A g−1, respectively) and cycling performance (805.3 mA h g−1 at 0.1 A g−1 after 100 cycles) among the TiO2 supported MoS2 based composites reported previous. The synergistic strategy can be expected to benefit the rational design of other anode materials for high-performance LIBs.Smart composites composed of defect-rich MoS2 shell, in which the carbon coats TiO2via Ti–O–C bonds and connects with the defect-rich MoS2 through intimate interfacial contact. The new-found synergistic effect between rich defect in few-layer MoS2 nanosheets and abundant interfaces in the composites results in high-performance of lithium-ion battery anode materials.

•Free-standing hierarchical nanoporous graphene (hnp-G) film was successfully fabricated by a simple method.•The symmetric solid-state supercapacitor, assembled using two pieces of hnp-G films, offers ultrahigh energy and power densities and exhibits almost identical performance at various curvatures and excellent lifetime.Continuously hierarchical nanoporous graphene (hnp-G) films are synthesized by a combination of low-temperature CVD growth of hydrogenated graphite (HG) coating on nanoporous copper (NPC) and rapid catalytic pyrolysis of HG at high temperature. Low-temperature growth of HG coating on NPC can obviously delay the coarsening evolution of NPC at high temperature, providing the precondition to obtain hnp-G with small pore size (1–150 nm) by catalytic pyrolysis at high temperature. The high specific surface area (1160 m2/g) of hnp-G are mainly originated from the external surface (954.7 m2/g), resulting in fully accessible channels for ion transport. More importantly, the continuously 3D hierarchical nanoporous structure and fully wettability of the hnp-G with gelled electrolyte not only effectively prevent the restacking of graphene even under dramatic squeezing but also guarantee the continuous and short electron/ion diffusion pathway in the whole electrodes, resulting in ultrahigh specific capacitance (38.2 F/cm3 based on the device) and excellent rate performance. The symmetric SC offers ultrahigh energy density (2.65 mW h/cm3) and power density (20.8 W/cm3) and exhibits almost identical performance at various curvatures and excellent lifetime (94% retention after 10,000 cycles), suggesting its wide application potential in powering wearable/miniaturized electronics.

Carbon nanotube (CNT)-reinforced 6061Al alloy matrix composites were prepared by chemical vapor deposition (CVD) combined with hot extrusion technique. During the preparation process, the 6061Al flakes obtained by ball milling of the 6061Al spherical powders were subjected to surface modification to introduce a hydrophilic polyvinyl alcohol (PVA) membrane on their surface (6061Al@PVA) to bond strongly with nickel acetate [Ni(II)]. Then the 6061Al@PVA flakes bonded with Ni(II) were calcined and reduced to Ni nanoparticles, which were then heat-treated at 580 °C to remove PVA for obtaining even Ni/6061Al catalyst. After that, the as-obtained Ni/6061Al catalyst was employed to synthesize CNTs on the surface of the 6061Al flakes by CVD. After hot extrusion of the CNT/6061Al composite powders, the as-obtained CNT/6061Al bulk composites with 2.26 wt% CNTs exhibited 135% increase in yield strength and 84.5% increase in tensile strength compared to pristine 6061Al matrix.

A simple and scalable method which combines traditional powder metallurgy and chemical vapor deposition is developed for the synthesis of mesoporous free-standing 3D graphene foams. The powder metallurgy templates for 3D graphene foams (PMT-GFs) consist of particle-like carbon shells which are connected by multilayered graphene that shows high specific surface area (1080 m2 g–1), good crystallization, good electrical conductivity (13.8 S cm–1), and a mechanically robust structure. The PMT-GFs did not break under direct flushing with DI water, and they were able to recover after being compressed. These properties indicate promising applications of PMT-GFs for fields requiring 3D carbon frameworks such as in energy-based electrodes and mechanical dampening.Keywords: 3D graphene foam; free-standing; mesoporous; powder metallurgy; solid carbon source;

In this study, we demonstrated nitrogen-doped graphene network supported few-layered graphene shell encapsulated Cu nanoparticles (NPs) (Cu@G-NGNs) as a sensing platform, which were constructed by a simple and scalable in situ chemical vapor deposition (CVD) technique with the assistance of a self-assembled three-dimensional (3D) NaCl template. Compared with pure Cu NPs and graphene decorated Cu NPs, the graphene shells can strengthen the plasmonic coupling between graphene and Cu, thereby contributing to an obvious improvement in the local electromagnetic field that was validated by finite element numerical simulations, while the 3D nitrogen-doped graphene walls with a large surface area facilitated molecule adsorption and the doped nitrogen atoms embedded in the graphene lattice can reduce the surface energy of the system. With these merits, a good surface enhanced Raman spectroscopy (SERS) activity of the 3D Cu@G-NGN painting film on glass was demonstrated using rhodamine 6G and crystal violet as model analytes, exhibiting a satisfactory sensitivity, reproducibility and stability. As far as we know, this is the first report on the in situ synthesis of nitrogen-doped graphene/copper nanocomposites and this facile and low-cost Cu-based strategy tends to be a good supplement to Ag and Au based substrates for SERS applications.

Uniform transition metal sulfide deposition on a smooth TiO2 surface to form a coating structure is a well-known challenge, caused mainly due to their poor affinities. Herein, we report a facile strategy for fabricating mesoporous 3D few-layered (<4 layers) MoS2 coated TiO2 nanosheet core–shell nanocomposites (denoted as 3D FL-MoS2@TiO2) by a novel two-step method using a smooth TiO2 nanosheet as a template and glucose as a binder. The core–shell structure has been systematically examined and corroborated by transmission electron microscopy, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. It is found that the resultant 3D FL-MoS2@TiO2 as a lithium-ion battery anode delivers an outstanding high-rate capability with an excellent cycling performance, relating to the unique structure of 3D FL-MoS2@TiO2. The 3D uniform coverage of few-layered (<4 layers) MoS2 onto the TiO2 can remarkably enhance the structure stability and effectively shortens the transfer paths of both lithium ions and electrons, while the strong synergistic effect between MoS2 and TiO2 can significantly facilitate the transport of ions and electrons across the interfaces, especially in the high-rate charge–discharge process. Moreover, the facile fabrication strategy can be easily extended to design other oxide/carbon–sulfide/oxide core–shell materials for extensive applications.

Three-dimensional (3D) hierarchical porous carbons (indicated with 3D HPCs) were synthesized via a simple one-pot method using the self-assembly of various water-soluble NaX salts (X: Cl−, CO32−, SiO32−) as structure-directing templates. By controlling crystallization and assembly of multi-scale salts via a freeze-drying process, 3D porous carbon networks with tailored pore size distribution have been generated by calcining the salts/glucose self-assembly followed by removing the 3D self-assembly of NaX salts via simple water washing. When their applications were evaluated for supercapacitor electrodes as an example, the as-constructed 3D HPCs with large surface area, high electron conductivity, facile electrolyte penetration and robust structure exhibited excellent capacitive performance, namely, high specific capacitance (320 F g−1 at 0.5 A g−1), outstanding high rate capacitance retention (126 F g−1 at 200 A g−1), and superior specific capacitance retention ability (nearly no discharge capacity decay between 1000 and 10000 continuous charge–discharge cycles at a high current density of 5 A g−1). Based on our soluble salt self-assembly-assisted synthesis concept, it was revealed that salts in seawater are also very suitable for low-cost and scalable synthesis of 3D HPCs with good capacitive performance, which pave the way for advanced utilization of seawater.

Poor rate capability and cycling performance are the major barriers to the application of lithium rich layered oxides (LLOs) as the next generation cathodes materials for lithium-ion batteries. In this paper, a novel surface double phase network modification has been applied to enhance the rate property of Li1.2Co0.13Ni0.13Mn0.54O2 (LR) via flexible electrostatic heterocoagulation and thermal treatment. The template action of multiwalled carbon nanotubes (MWCNTs) network on LR clusters results in the spinel phase network formation at the interface between the LR and MWCNTs. The phase transformation process from layered component toward spinel phase is identified through the detailed investigation of the interface using high-resolution transmission electron microscopy, fast Fourier transformation, and the detailed analysis on the transformation of simulated diffraction patterns. The double phases stretch two sets of networks with both fine Li ion and electron conductivity onto and within the clusters of LR, lowering the surface resistance, reducing the electrochemical polarization, and as a result, significantly enhancing the rate capability of LR. The double phase network modification, combining MWCNT coagulation and spinel phase modification, has profound potential in accelerating kinetics for LLOs.Keywords: double phase network; lithium rich layered oxides; rate capability; surface modification

Carbon nanochains (CNCs) were synthesized by a facile chemical vapor deposition process consisting of a 1D chain of interconnected carbon nano-onions for potential application in supercapacitors. In this study, the CNCs were further activated by a chemical method using potassium hydroxide (KOH) as the activation agent to obtain micro-meso pore structures. To improve the specific surface area (SSA) and optimize the pore size distribution (PSD) to enhance the capacitance performance, we investigated the activation parameters, including the KOH content, temperature and duration. The results indicated that CNCs with a hierarchical pore structure and high SSA could be achieved using an activation process with a KOH-to-CNC ratio of 2 at 900 °C for 20 h. The mechanism is also discussed. The activation temperature and duration affect the promotion of the carbon graphitization and exaggeration of the carbon etching. The CNCs activated using the optimal parameters exhibited a high capacitance performance of 112.7 F g–1 at 50 mV s–1 with excellent stability in 6 M KOH electrolyte, which was due to the improved surface and micromesoporosity without sacrificing their electronic transmission properties.

A micrometer-thin solid-state supercapacitor (SC) was assembled using two pieces of porous carbon nanofibers/ultrathin graphite (pCNFs/G) hybrid films, which were one-step synthesized by chemical vapor deposition using copper foil supported Co catalyst. The continuously ultrathin graphite sheet (∼25 nm) is mechanically compliant to support the pCNFs even after etching the copper foil and thus can work as both current collector and support directly with nearly ignorable fraction in a SC stack. The pCNFs are seamlessly grown on the graphite sheet with an ohmic contact between the pCNFs and the graphite sheet. Thus, the accumulated electrons/ions can duly transport from the pCNFs to graphite (current collector), which results in a high rate performance. The maximum energy density and power density based on the whole device are up to 2.4 mWh cm–3 and 23 W cm–3, which are even orders higher than those of the most reported electric double-layer capacitors and pseudocapacitors. Moreover, the specific capacitance of the device has 96% retention after 5000 cycles and is nearly constant at various curvatures, suggesting its wide application potential in powering wearable/miniaturized electronics.Keywords: chemical vapor deposition; device performance; flexible solid-state supercapacitor; porous carbon nanofiber; ultrathin graphite;

A facile and scalable 2D spatial confinement strategy is developed for in situ synthesizing highly crystalline MoS2 nanosheets with few layers (≤5 layers) anchored on 3D porous carbon nanosheet networks (3D FL-MoS2@PCNNs) as lithium-ion battery anode. During the synthesis, 3D self-assembly of cubic NaCl particles is adopted to not only serve as a template to direct the growth of 3D porous carbon nanosheet networks, but also create a 2D-confined space to achieve the construction of few-layer MoS2 nanosheets robustly lain on the surface of carbon nanosheet walls. In the resulting 3D architecture, the intimate contact between the surfaces of MoS2 and carbon nanosheets can effectively avoid the aggregation and restacking of MoS2 as well as remarkably enhance the structural integrity of the electrode, while the conductive matrix of 3D porous carbon nanosheet networks can ensure fast transport of both electrons and ions in the whole electrode. As a result, this unique 3D architecture manifests an outstanding long-life cycling capability at high rates, namely, a specific capacity as large as 709 mAh g–1 is delivered at 2 A g–1 and maintains ∼95.2% even after 520 deep charge/discharge cycles. Apart from promising lithium-ion battery anode, this 3D FL-MoS2@PCNN composite also has immense potential for applications in other areas such as supercapacitor, catalysis, and sensors.Keywords: 2D space-confined synthesis; 3D network; carbon nanosheet; intimate interfacial contact; lithium-ion battery anode; MoS2;

Microstructural evolution in a new kind of aluminum (Al) alloy with the chemical composition of Al-8.82Zn-2.08Mg-0.80Cu-0.31Sc-0.3Zr was investigated. It is found that the secondary phase MgZn2 is completely dissolved into the matrix during a short homogenization treatment (470°C, 1 h), while the primary phase Al3(Sc,Zr) remains stable. This is due to Sc and Zr additions into the Al alloy, high Zn/Mg mass ratio, and low Cu content. The experimental findings fit well with the results calculated by the homogenization diffusion kinetics equation. The alloy shows an excellent mechanical performance after the short homogenization process followed by hot-extrusion and T6 treatment. Consequently, a good combination of low energy consumption and favorable mechanical properties is obtained.

A high-quality ultrathin anatase TiO2 nanosheet (ANT)/reduced graphene oxide (RGO) composite is successfully prepared by a simple one-step hydrothermal synthetic route. The unique 2-D integrative features and mesoporous characteristic of the ultrathin ATN/RGO composite with a large surface area and outstanding stability are very favorable for lithium storage. A high initial discharge capacity (256.4 mA h g−1 at 0.2C), a high initial Coulombic efficiency (86%), a high rate capability (225.7, 202, 183, 157, 118 and 88.3 mA h g−1 at 0.5, 1, 2, 5, 10, and 20C, respectively, 1C = 167.5 mA h g−1), and a superior cyclability (174.2 mA h g−1 after 200 cycles at 1C and 112.9 mA h g−1 after 260 cycles at 10C) are achieved by using the ultrathin ATN/RGO composite as an anode material for lithium-ion-batteries. A detailed comparative study of the electrochemical properties of P25 nanoparticles, ATNs, ATN/RGO, and ultrathin ATN/RGO composites reveals that the significantly enhanced lithium storage capability is attributed to the ultrathin TiO2 nanosheets with short ion diffusion paths facilitating Li+ insertion/extraction, RGO conductive supports for fast electron transport, and the extra Li storage at the RGO/TiO2 interface.

Graphene/metal-oxide nanocomposites have been widely studied as anode materials for lithium ion batteries and exhibit much higher lithium storage capacity beyond their theoretical capacity through mechanisms that are still poorly understood. In this research, we present a comprehensive understanding in microscale of the discharge process of graphene/TiO2 containing surface, bulk, and interfacial lithium storage based on the first-principles total energy calculations. It is revealed that interfacial oxygen atoms play an important role on the interfacial lithium storage. The additional capacity originating from surface and interfacial lithium storage via an electrostatic capacitive mechanism contributes significantly to the electrode capacity. The research demonstrates that for nanocomposites used in energy storage materials, electrode and capacitor behavior could be optimized to develop high-performance electrode materials with the balance of storage capacity and rate.Keywords: discharge process; first-principles calculations; interfacial lithium storage; interfacial oxygen atoms; pseudocapacity-like storage mechanism

Two kinds of TiO2 with novel structures, interpenetrating anatase TiO2 tablets (IP-TiO2), and overlapping anatase TiO2 nanosheets (OL-TiO2) with exposed {0 0 1} facets, are synthesized. The graphene oxide (GO) supported ultrathin TiO2 nanosheets (OL-TiO2/GO) is also prepared by one-pot hydrothermal method. The microscopic feature, morphology, phase, and nitrogen adsorption–desorption isotherms are characterized. The performance of photocatalytic degradation of methyl blue is also measured. Compared with IP-TiO2, the OL-TiO2 with GO possess higher photocatalytic efficiency. The GO can improve the photocatalytic property by increasing specific surface area, accelerating the separation of electron–hole pairs, as well as extending the electron life. The growth process of TiO2 nanosheets on graphene oxide layers probably follows a step-growth mechanism with F− as morphology controlling agent. The steps on the surface can improve the photocatalytic activity further due to the increase of dangling bonds of 5-coordinated Ti (Ti5c) which are considered to be the active sites in the photocatalytic reaction.

6061 aluminum-alloy matrix composites are drawing greater attention due to their low density, excellent mechanical properties and wear resistance. In this study, in-situ generated MgAl2O4 spinel whiskers reinforced 6061Al alloy matrix composites were fabricated and solutionizing and age hardening treatment was performed on the composites in a temperature range of 160–210 °C. The microstructure and mechanical properties of the composite were investigated and the influences of in-situ generated whiskers on aging behaviors of the composite were also discussed. The results show that the whiskers exhibit a homogeneous distribution with good interface bonding with the matrix. The hardness and ultimate tensile strength (UTS) increase with increasing content of the whisker, whereas the ductility decreases at the same time. The properties of the composites attained a peak value of 195 HV in hardness and 400 MPa in UTS after aging for 30 min at 190 °C. Compared with the 6061Al alloy, the presence of whiskers could accelerate the aging kinetics of composites due to the high density dislocations formed during the fabrication process.

A facile and scalable in situ chemical vapor deposition (CVD) technique using metal precursors as a catalyst and a three-dimensional (3D) self-assembly of NaCl particles as a template is developed for one-step fabrication of 3D porous graphene networks anchored with Sn nanoparticles (5–30 nm) encapsulated with graphene shells of about 1 nm (Sn@G-PGNWs) as a superior lithium ion battery anode. In the constructed architecture, the CVD-synthesized graphene shells with excellent elasticity can effectively not only avoid the direct exposure of encapsulated Sn to the electrolyte and preserve the structural and interfacial stabilization of Sn nanoparticles but also suppress the aggregation of Sn nanoparticles and buffer the volume expansion, while the interconnected 3D porous graphene networks with high electrical conductivity, large surface area, and high mechanical flexibility tightly pin the core–shell structure of Sn@G and thus lead to remarkably enhanced electrical conductivity and structural integrity of the overall electrode. As a consequence, this 3D hybrid anode exhibits very high rate performance (1022 mAh/g at 0.2 C, 865 mAh/g at 0.5 C, 780 mAh/g at 1 C, 652 mAh/g at 2 C, 459 mAh/g at 5 C, and 270 mAh/g at 10 C, 1 C = 1 A/g) and extremely long cycling stability even at high rates (a high capacity of 682 mAh/g is achieved at 2 A/g and is maintained approximately 96.3% after 1000 cycles). As far as we know, this is the best rate capacity and longest cycle life ever reported for a Sn-based lithium ion battery anode.Keywords: 3D network; chemical vapor deposition; core−shell; graphene; high-rate; in situ synthesis; lithium storage; nanohybrid; Sn

A facile and scalable strategy for the synthesis of discrete, homogeneous and small (mostly 5–15 nm) Fe3O4 nanocrystals embedded in a partially graphitized porous carbon matrix was developed, which involved the simple mixing of a metal precursor (Fe(NO3)3·9H2O), a carbon precursor (C6H8O7), and a dispersant (NaCl) in an aqueous solution followed by calcination at 600 °C for 2 h under Ar. As the anode materials for lithium-ion batteries, the Fe3O4/carbon composite with 55.24 wt% Fe3O4 exhibited superior electrochemical performances, such as high reversible lithium storage capacity (834 mA h g−1 at 1 C after 60 cycles, 1 C = 924 mA g−1), high Coulombic efficiency (∼100%), excellent cycling stability, and superior rate capability (588 mA h g−1 at 5 C and 382 mA h g−1 at 10 C). These excellent electrochemical performances could be attributed to the robust porous carbon matrix with a partially graphitized structure for embedding a mass of small Fe3O4 nanocrystals, which not only provided excellent electronic conductivity, short transportation length for both lithium ions and electrons, and enough elastic buffer space to accommodate volume changes upon lithium insertion/extraction, but also could effectively avoid agglomeration of the Fe3O4 nanocrystals and maintain the structural integrity of the electrode during the charge–discharge process. It is believed that the Fe3O4/carbon composite synthesized by the current method is a promising anode material for high energy and power density lithium-ion batteries.

Highly ordered hierarchical TiO2 nanostructures involving primary honeycomb and secondary nanoparticles and nanowires are prepared by a two-step facile process. The TiO2 nanotube arrays grow first on Ti foil through anodization. After the wet-chemical reaction of the TiO2 nanotube arrays with alkaline and acid solution in turn, the hierarchical nanostructures wire-in-honeycomb and porous honeycomb are obtained by a dissolution–coagulation and dissolution–adsorption mechanism, respectively. The power conversion efficiency of the hierarchical TiO2 honeycomb nanostructures for the dye-sensitized solar cells (DSCs) shows a significant improvement, as high as 5.73%, increased by 1.42 times compared with that of TiO2 nanotube arrays. The performance improvement of DSCs based on the hierarchical nanostructures is attributed to the increase in the specific surface area.Keywords: dye-sensitized solar cells; hierarchical honeycomb nanostructure; photoanode; titanium dioxide;

Lithium-rich layered cathode Li1.2Mn0.54Ni0.13Co0.13O2 is synthesized by a co-precipitation method followed by high-temperature treatment and surface coated with different amount of amorphous FePO4. The microstructure and electrochemical performance of the as-prepared cathode materials are investigated systematically. It is demonstrated that the Li1.2Mn0.54Ni0.13Co0.13O2 particles are uniformly coated with amorphous FePO4. With proper amount of amorphous FePO4 coating layer, significant improvements in discharge capacity, initial Coulombic efficiency, rate capability, cycle performance, and thermal stability are achieved at room temperature. Specifically, the 3 wt.% FePO4-coated cathode exhibits the highest discharge specific capacities (271.7 mAh g−1 at C/20), improved initial Coulombic efficiency (85.1%), and best cyclability (discharge capacity of 202.6 mAh g−1 at C/2 after 100 cycles), while the 1 wt.% FePO4-coated cathode displays the best rate capability (194.3 mAh g−1 at 1 C rate and 167.9 mAh g−1 at 2 C rate). The charge–discharge curves and electrochemical impedance spectra reveal that the improved electrochemical performances are due to the suppression of both the oxygen vacancy elimination at the end of the first charge and side reactions of the cathode with the electrolyte, as well as the decrease in charge transfer polarization by the FePO4 coating layer.Highlights► Li1.2Mn0.54Ni0.13Co0.13O2 coated with a uniform layer of FePO4 was synthesized. ► Electrochemical performance was significantly improved by FePO4 coating. ► FePO4 coating layer suppresses the side reactions with the electrolyte. ► FePO4 coating enhances kinetics of Li1.2Mn0.54Ni0.13Co0.13O2 material.

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 2.5 wt.% CNTs exhibit the ultimate tensile strength of 334 MPa 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.Highlights► The in situ chemical vapor deposition combined with ball milling for a short time are used to synthesize CNT/Al composites. ► The well dispersed CNT reinforcement is deeply embedded in the Al powder forming an effective interface bonding with matrix. ► The 2.5 wt.%-CNT/Al composites exhibit the ultimate tensile strength of 334 MPa and ductility of ∼18% elongation to failure. ► Well-balanced strength and ductility are achieved in CNT-reinforced Al composites.

•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.A mass of amorphous carbon nanotubes (ACNTs) have been synthesized by chemical vapor deposition of C2H2 directly on Fe76Si9B10P5 glassy alloy particles without the addition of an external catalyst at 550 °C for 1 h. The ACNTs is 1–5 μm in length and 5–30 nm in diameter and has a Brunauer–Emmett–Teller surface area of 81.4 m2/g. Investigations on the ACNT growth process confirmed that the initial stage for appearance of isolated islands (α-Fe nanoparticles), which might be due to stress and surface breakup generated during high temperature CVD process, would be the decisive step for the ACNT growth.

•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.Bulk Ti2AlC–Al2O3/TiAl composites were in situ synthesized by vacuum sintering mechanically alloyed Ti–50 at.% Al powders coated with carbon nanotubes (CNTs). The pre-alloyed Ti–50 at.% Al powder was obtained by ball milling Ti and Al powders. The multi-walled carbon nanotubes as the carbon resource were covered on the surface of the pre-alloyed powders by immersing them into a water solution containing the CNTs. A zwitterionic surfactant was used to enhance the dispersion of the CNTs on the powder surface. The samples were cold pressed and sintered in vacuum at temperatures from 950 to 1250 °C, respectively. The results show that the reaction of forming Ti2AlC can be achieved below 950 °C, which is 150 °C lower than in the Ti–Al–TiC system and 250 °C lower than for the Ti–Al–C system due to the addition of CNTs. Additionally, the reinforcement of Al2O3 particles was introduced in situ in Ti2AlC/TiAl by the drying process and subsequent sintering of the composite powders. Dense Ti2AlC–Al2O3/TiAl composites were obtained by sintering at 1250 °C and exhibited a homogeneous distribution of Ti2AlC, Al2O3 and precipitated Ti3Al particles and a resulting high hardness.

•TiO2 nanocrystalline film with through-hole cracks is fabricated by gel chapping.•The CNTs/TiO2 nanocomposites fabrication method guarantees the contact of CNTs with current collector.•The conversion efficiency is 3 times superior to that of TiO2 nanocrystalline film.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.

A facile and scalable in situ synthesis strategy is developed to fabricate carbon-encapsulated Fe3O4 nanoparticles homogeneously embedded in two-dimensional (2D) porous graphitic carbon nanosheets (Fe3O4@C@PGC nanosheets) as a durable high-rate lithium ion battery anode material. With assistance of the surface of NaCl particles, 2D Fe@C@PGC nanosheets can be in situ synthesized by using the Fe(NO3)3·9H2O and C6H12O6 as the metal and carbon precursor, respectively. After annealing under air, the Fe@C@PGC nanosheets can be converted to Fe3O4@C@PGC nanosheets, in which Fe3O4 nanoparticles (∼18.2 nm) coated with conformal and thin onion-like carbon shells are homogeneously embedded in 2D high-conducting carbon nanosheets with a thickness of less than 30 nm. In the constructed architecture, the thin carbon shells can avoid the direct exposure of encapsulated Fe3O4 to the electrolyte and preserve the structural and interfacial stabilization of Fe3O4 nanoparticles. Meanwhile, the flexible and conductive PGC nanosheets can accommodate the mechanical stress induced by the volume change of embedded Fe3O4@C nanoparticles as well as inhibit the aggregation of Fe3O4 nanoparticles and thus maintain the structural and electrical integrity of the Fe3O4@C@PGC electrode during the lithiation/delithiation processes. As a result, this Fe3O4@C@PGC electrode exhibits superhigh rate capability (858, 587, and 311 mAh/g at 5, 10, and 20 C, respectively, 1 C = 1 A/g) and extremely excellent cycling performance at high rates (only 3.47% capacity loss after 350 cycles at a high rate of 10 C), which is the best one ever reported for an Fe3O4-based electrode including various nanostructured Fe3O4 anode materials, composite electrodes, etc.Keywords: 2D nanosheet; carbon-encapsulated Fe3O4 nanoparticles; core−shell; energy storage; high rate; in situ synthesis; nanohybrid

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 1–4 nm 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.

•Li1.2Mn0.54Ni0.13Co0.13O2 coated with a uniform ZrO2 nano-layer was synthesized.•Electrochemical performance was significantly improved by ZrO2 coating.•ZrO2 coating layer suppresses the side reactions with the electrolyte.Lithium-rich layered cathode material Li[Li0.2Mn0.54Ni0.13Co0.13]O2 with spherical morphology is prepared via co-precipitation method followed by high-temperature treatment and surface coated with a uniform nano-layer of ZrO2 by controlled-hydrolysis of Zirconium(IV) Propoxide. The results show that Li[Li0.2Mn0.54Ni0.13Co0.13]O2 with a well-ordered layered structure consists of small and homogenous primary particles ranging from 100 nm to 200 nm.The ZrO2 layer with nano-sized particles is coated uniformly on the matrix particle surface. A notable improvement of the cathode coated by ZrO2 is obtained in cycle performance from charge–discharge cycling tests in the range of 2.0–4.8 V, and the optimum amount of ZrO2 coating which maximizes the capacity retention is 1 wt.%. A high initial discharge capacity of 253.1 mAh/g at 0.1C is obtained for the 1 wt.% ZrO2-coated sample, and it maintains a capacity of 207.3 mAh/g after 50 cycles at 0.5C and a capacity of 235.3 mAh/g after 50 cycles at 0.2C. The improved cycling performance of ZrO2-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 is attributed to the decrease of electrolyte decomposition reactions and the alleviation of the impedance due to the existence of ZrO2 coating layer.

Recently, the highly isolated TiO2 nanowire array has attracted much interest because of its advantages in a wide range of applications of this material, including dye sensitized solar cells and photocatalysis. The present work describes a high isolation of TiO2 nanowires in the cellular protected nanowire (CPNW) array obtained by KOH–HCl alternative treatment of the as-anodized TiO2 nanotube array at room temperature. The nanowires in the cells are highly separated from each other due to the successful suppression of the domino bundling effect by the cells. The mechanism of the CPNW formation is argued to be the dissolution–precipitation of TiO2 nanoclusters. It is demonstrated that the nanopore-confined TiO2 colloid, due to the different influence of drag force associated with the confined Brownian motion, will essentially precipitate in the center of the nanopore to form an isolated TiO2 nanowire. Benefiting from the additional surface area and high isolation of TiO2 nanowires in the CPNW array, the TiO2 CPNW array has a better performance than the TiO2 nanotube array in the application of DSSCs.

Discrete, homogenous and ultrasmall (mostly 2–4 nm) L10-ordered fct FePt nanoparticles encapsulated in well-graphitized thin carbon shells have been prepared by a one-step solid-phase synthesis technique, which can be applied for the production of a number of metal alloy nanoparticles encapsulated in carbon shells. The as-synthesized FePt@C nanoparticles of size 2.1 ± 0.4 nm present superparamagnetic properties at room temperature. The 3.3 ± 0.6 nm size FePt@C nanoparticles have a high coercivity, up to 4.56 kOe at room temperature, and superior chemical stability in a high concentration HCl (10 M) solution. Furthermore, these nanoparticles functionalized non-covalently by phospholipid-poly(ethylene)glycol show biocompatibility with the tested cells (mouse macrophage and mouse L929 fibroblasts cells) in all test concentrations (0.025–0.2 mg mL−1).

Hybrid structures combining fullerenes and carbon nanotubes have exhibited exciting properties. However, the low efficiency and complex process of such assembly restrict their practical applications. We report a single-step procedure to synthesize the fullerene-intercalated (including endohedral metallofullerene (Y@Cn)) porous carbon nanofibers (pCNFs) by chemical vapor deposition (CVD) using a Fe/Y catalyst on a copper substrate. Fullerenes were simultaneously synthesized with the pCNF growth during the CVD process. Instead of attaching them on the surface of the CNFs, the fullerenes were inserted in the graphitic interlayer spacing, inducing micro- and mesopores in CNFs. The growth mechanism of the fullerene-intercalated pCNFs was discussed.

In this study, we report an efficient method for synthesis of well-graphitized hollow carbon nano-onions (CNOs). CNOs were firstly fabricated by chemical vapor deposition (CVD) method at 850 °C using an Fe–Ni alloy catalyst with diameters of 10–15 nm. Then hollow CNOs were obtained by annealing as-prepared CNOs at 1100 °C for 3 h. It is found that during the CVD growth, the presence of nickel retards the deactivation of Fe–Ni–C austenite, providing the possibility for the growth of up to two hollow CNOs from each alloy particle. The subsequent high-temperature annealing led to the escaping of the Fe–Ni alloy from the graphitic layers, and the re-catalysis of precipitation and graphitization of the carbon atoms previously dissolved in the alloy particle (Fe0.64Ni0.36) to form hollow CNOs. The hollow CNOs exhibit good performance as materials for electrochemical hydrogen storage, with a discharge capacity of 481.6 mAh/g under a current density of 500 mA/g, corresponding to a hydrogen storage capacity of 1.76 wt.%. Our results demonstrate that the hollow CNOs are promising materials as a storage medium for hydrogen as a fuel source.

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.Highlights►MWCNTs were synthesized by using Cu catalyst at a low temperature (600 °C). ►The Cu catalyst we used was not modified in acid–base properties. ►Al was first used to support the Cu catalyst in the synthesis of MWCNTs. ►The Al carrier plays a key role in the catalytic growth of MWCNTs.

The poor drop-shock resistance of near-eutectic Sn–Ag–Cu (SAC) solder interconnects drives the research and application low-Ag SAC solder alloys, especially for Sn–1.0Ag–0.5Cu (SAC105). In this work, by dynamic four-point bend testing, we investigate the drop impact reliability of SAC105 alloy ball grid array (BGA) interconnects with two different surface mounting methods: near-eutectic solder paste printing and flux dipping. The results indicate that the flux dipping method improves the interconnects failure strain by 44.7% over paste printing. Further mechanism studies show the fine interfacial intermetallic compounds (IMCs) at the printed circuit board side and a reduced Ag content inside solder bulk are the main beneficial factors overcoming other negative factors. The flux dipping SAC105 BGA solder joints possess fine Cu6Sn5 IMCs at the interface of solder/Cu pads, which increases the bonding strength between the solder/IMCs and the fracture resistance of the IMC grains themselves. Short soldering time of flux dipping joints above the solder alloy liquidus mitigates the growth of interfacial IMCs in size. In addition, a reduced Ag content in flux dipping joint bulk causes a low hardness and high compliance, thus increasing fracture resistance under higher-strain rate conditions.

Well graphitized carbon nano-onions (CNOs) with large yield have been synthesized by the catalytic decomposition of methane over an unsupported Ni–Fe catalyst at 850 °C. The unsupported Ni–Fe catalyst was prepared by a reduction-substitution method. In the Ni–Fe alloy particle, α-Fe(Ni) phase (kamacite) transforms to γ-Fe–Ni phase at the high temperature for hydrogen reduction and chemical vapor deposition. The synthesized CNOs contain either a Fe0.64Ni0.36 particle or a hollow core with thick graphitic layers and a polyhedral shape. Based on the characterization, we believe that the catalyst involved in the synthesis of carbon products is Fe–Ni–C austenite rather than the γ-Fe–Ni phase (Fe0.64Ni0.36). A growth mechanism for the CNOs is proposed.

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.

In order to obtain homogeneously dispersed carbon nanotube (CNT) reinforcement with well structure in Al powder, a novel and simple approach was developed as a means of overcoming the limits of traditional mixing methods. This process involves the even deposition of Ni catalyst onto the surface of Al powder by impregnation route with a low Ni content (0.5 wt.%) and in situ synthesis of CNTs in Al powder by chemical vapor deposition. The in situ synthesized CNTs with well-crystallized bamboo-like structure in the composite powders can obviate the reaction with Al below 1000 °C. The feasibility of fabricating CNT/Al composites with high mechanical properties using the as-prepared composite powders was proved by our primary test, which indicated that the compressive yield stress and elastic modulus of 1.5 wt.%-CNT/Al composites synthesized by hot extrusion are 2.2 and 3.0 times as large as that of the pure Al matrix.

A mass of multi-wall carbon nanohorns (CNHs) were synthesized by simple chemical vapor deposition of methane over Ni/Al2O3. Transmission electron microscopy was used to characterize these CNHs. The results showed that the purity of CNHs was about 40–50% and these CNHs were with well graphitized multi-walled structures. The mean diameter of CNHs was about 20 nm, which is larger than those prepared by the CO2 laser method, and the length of CNHs was in the range of 50–500 nm. Moreover, the growth mechanism of CNHs was discussed.

Structural evolutions of carbon onions and carbon coated nanocrystals of nickel during annealing process were investigated. X-ray diffraction, Raman and transmission electron microscope were used to investigate their structural variation. The results showed that annealing (700 °C) of the carbon onions resulted in the shrinkage of hollow core of carbon onions and reduction of the interlayer spacing between carbon onion shells. And the compressed onion structure took a perfect spheroidal shape. However, the structure of the annealed carbon coated Ni nanoparticles presented that the Ni nanoparticles (5–30 nm) escaped from carbon encapsulation and congregated to large Ni particles (30–180 nm), and the carbon coating was disintegrated to small disorder graphite pieces. When the Ni was removed from the carbon coated Ni nanoparticles and then was annealed at 700 °C for 4 h, it was found that these hollow carbon onions presented the similar structural evolution as the above carbon onions.

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 10 wt% Fe, while carbon coated metal nanoparticles resulted from Fe/Al2O3 catalyst with 15 wt% Fe, but for the Fe/Al2O3 catalyst with 5 wt% Fe, only amorphous carbon has been obtained.

Ceria decorated carbon nanotubes (CNTs) were in-situ synthesized by chemical vapor deposition using a Ni/Ce/Cu catalyst. Ceria nanoparticles, with a diameter of about 3–8 nm, were highly dispersed on the CNTs, and it is believed that they are formed at the same time as the CNTs.

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.

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 2–10 nm carbon coating shell was in the range of 5–80 nm. 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.

A mass of hollow carbon nanospheres was fabricated by chemical vapor deposition of methane over Ni/Al2O3 catalyst at 600 °C. The products were characterized with scanning electron microscope, transmission electron microscope, and high-resolution transmission electron microscope images. The results showed that the external diameter of the hollow carbon nanospheres was 5–90 nm and the thickness of the wall was about 15 nm. And a possible formation mechanism of the hollow carbon nanospheres was discussed.

Metal filled carbon nanotubes (CNTs) have been successfully synthesized by CVD using a novel Ni/Y catalyst supported on copper powder, which opens a new route for the fabrication of the CNTs reinforced copper matrix composites by directly synthesizing CNTs in copper. The growth processes of the CNTs are investigated in this paper. TEM analysis reveals that two kinds of carbon nanostructures, onion-like carbon nanospheres and a little amount of CNTs, coexist in the initial growth process. Along with the reaction time increased, onion-like carbon nanospheres coalesce and CNTs become more and longer. This is hard to be explained by previous reported mechanism mode. Therefore, a new growth mode—sphere-tube growth mechanism model is suggested for the CNTs growth based on our experiments.

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.

Carbon nanotubes (CNTs) (Fe)/hydroxyapatite (HA) composite powder with CNTs homogeneously dispersed was successfully prepared by a novel process, which involved producing Fe2O3/HA precursor, calcination in N2 atmosphere and reduction in hydrogen of the Fe2O3/HA precursor to yield Fe/HA catalyst, and in situ synthesis of nanotubes by chemical vapor deposition over Fe/HA catalyst. These excellent CNTs(Fe)/HA composite powder was then employed to produce CNTs(Fe)/HA bulk composites. The CNTs(Fe)/HA bulk nanocomposites produced by pressing and sintering of the CNTs(Fe)/HA composite powder presented that the CNTs distributed homogenously and bonded strongly with the HA matrix. The effective enhancement of mechanical properties of the composites was indicated by a 226% increase in fracture toughness and 49% increase in flexural strength compared to monolithic HA bulk.

Reproducibility and predictability of pore size and relative density of open cell aluminum foams with spherical pores synthesized by the space-holder method have been studied and mechanical properties of the foam were investigated in light of its pore size and relative density. The results showed that the reproducibility and predictability of the compressive property and the control precision of relative density were improved with decreasing pore size. The compressive stress–strain curve increased with a increase in pore size and relative density.

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.

A mass of carbon onions have previously been successfully synthesized via catalytic decomposition of methane using nitrogen as a carrier gas over a Ni/Al catalyst. In this study, X-ray photoelectron spectroscopy characterization of the carbon onions shows that the as-grown carbon onions contained nitrogen and that the nitrogen concentration in the carbon onions increased with an increase in reaction time. When hydrogen is used as a carrier gas, it is found that no carbon onions are obtained, indicating that the carrier gas plays an important role in the synthesis of carbon onions and that there is an intimate relationship between carbon onion growth and nitrogen incorporation.

Carbon onions with diameters ranging from 5 to 50 nm and carbon-coated nickel nanoparticles with diameters ranging from 10 to 60 nm have been synthesized on a large scale over Ni/Al catalyst by chemical vapor deposition. The approximate ratio of Ni-filled to empty onions as observed by TEM is 1:3.5. In order to eliminate the nickel nanoparticle and obtain pure hollow carbon onions, HNO3 acid was used to dissolve the nickel from the carbon-coated nickel nanoparticles. The carbon onion particles thus obtained have hollow cores and are mainly composed of well-crystallized graphite, as characterized by high-resolution TEM and Raman spectroscopy. In addition, we proposed a simple purification mechanism for Ni-filled carbon onions based on TEM observations.

A mass of carbon onions have been successfully synthesized via catalytic decomposition of methane over an Ni/Al catalyst at a low-temperature (600 °C). The carbon onions as-obtained have diameters ranging from 5 to 50 nm and consist of several concentric carbon layers surrounding a hollow core.

Onion-like carbons were synthesized by annealing diamond nanoparticles at 1100–1400 °C. The diamond nanoparticles begin to graphitize in the range of 1100–1200 °C and all the particles transform into onion-like carbons at 1400 °C. The transformation temperature changes with the nanoparticle size. The onion-like carbons exhibit similarity to the original nanoparticles in shape.

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 20 wt.% nickel. The CNTs were multi-walled, 10–20 nm in diameter and up to 15 μm long. Hollow carbon onions were produced in the presence of a Ni/Al composite catalyst containing 80 wt.% nickel. The carbon onions were from 5 to 50 nm 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.

Nanocarbons with a variety of morphologies were found after diamond nanoparticles (ND) were annealed at a low temperature. The conversion of ND to nanocarbons is a process of structural evolution that causes increase of sp2 bonding structure and decrease of sp3 bonding structure in nanostructure. While being annealed, ND are converted to carbon onions and undergo phase transition in a series of ND → bucky diamond → carbon onions → graphitic ribbons. The structural evolution of nanocarbons reflects the higher stability of planar graphitic ribbons over carbon onions.The intersection of assembled onions forms the ignition point and the ribbon-like graphites are formed via a tangential relaxation to relieve the strain induced by the onion curvature. When the annealing time is increased, all the curved layers of assembled onions are changed into planar graphitic ribbons.

The laser gas nitriding process is an efficient technique for modification of materials. Composite coatings with a microstructure consisting of dendritic TiN/NiTi were fabricated on a substrate of NiTi by the laser gas nitriding process. Different nitrogen flow rates were supplied during the laser process in order to detect the influence of the TiN on the wear resistance. The wear resistance of the TiN/NiTi coatings was evaluated under sliding wear test conditions in 5% NaCl aqueous solution at room temperature. The results indicate that the TiN/NiTi coatings have excellent abrasive and adhesive wear resistance because of the high hardness and the proportion of the TiN.

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 10–20 nm 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.

Open cell aluminum foams with tailored porous morphology were synthesized by a space-holder method. Carbamide particles with different shapes were used as a space-holder to produce samples. Depending on the shape distribution of the carbamide particles, the morphology of the pores in the foams can be easily controlled. The foam samples with spherical-shaped pores showed higher compressive strength than those with strip-shaped pores.

Open cell aluminum foams were made by powder sintering process. A space-holder method used carbamide to produce samples with porosities between 50% and 80%. The results showed that spherical-shaped pores were obtained depending on the shape and size distribution of the space-holder and the compressive strength was in agreement with the theoretical relationship for the normalized yield strength.

Three types of carbon nano-onions (CNOs) including Ni@CNOs, Fe3C@CNOs and Fe0.64Ni0.36@CNOs nanoparticles have been synthesized by catalytic decomposition of methane at 850 °C using nickel, iron and iron-nickel alloy catalysts. Comparative and systematic studies have been carried out on the morphology, structural characteristics and graphitic crystallinity of these CNOs products. Furthermore, the electrochemical hydrogen storage properties of three types of CNOs have been investigated. Measurements show that the Ni@CNOs have the highest discharge capacity of 387.2 mAh/g, corresponding to a hydrogen storage of 1.42%. This comparison study shows the advantages of each catalyst in the growth of CNOs, enabling the controllable synthesis and tuning the properties of CNOs by mediating different metals and their alloy for using in the fuel cell system.Three types of metal contained carbon nano-onions have been synthesized. Their compositions, microstructures, and growth quality have been systematically studied. Their electrochemical hydrogen storage properties have been studied comparatively.Download full-size image

•Both graphene incorporation and defect engineering are carefully controlled and characterized for the first time.•Synergistic modulations of both electron and Li-ion transport kinetics are realized in the optimized G/TiO2/C/MoS2 anode.•The optimized anodes exhibit excellent capability at high current density after long-life cycles.•This work can open up an avenue for the rational design anode materials by synergistically electronic and ionic modulations.Integrating nanostructured MoS2 with low-volume-change and high-rate-performance TiO2 backbone to construct high structure stability MoS2-TiO2 based composites has been turned out to be an effective strategy. However, the long-life cycling performance at high current density of all reported MoS2-TiO2 based composites anodes is still suffered from their relatively low electron and ion transport kinetics. In this paper, we first demonstrate the successful synergistic regulations of both electron and ion transport kinetics benefits by controllable graphene incorporation and defect engineering in MoS2-TiO2 based anodes, leading to the dramatically enhanced LIBs performance. In this optimized structure with robust structure stability, few-layer MoS2 nanosheets are tightly anchored onto the surface of graphene/ultra-thin TiO2 nanosheets (G/UT-TiO2) backbone with chemical bonds. The graphene incorporation effectively improves the overall conductivity, while the defected structure of MoS2 shell can significantly facilitate Li-ions transport kinetics. As a result, the as-prepared optimized anode exhibits excellent capability (648 mAh g−1) at high current density (1 A g−1) after long-life (400) cycles, accompanied by outstanding rate performance. This work can open up an avenue for the rational design of various anode materials for high performance LIBs by synergistically structural, electronic and ionic modulations.Synergistic modulations of both electron and Li-ion transport kinetics are realized by controllable graphene incorporation and defect engineering for the first time. Moreover, this work can open up an avenue for the rational design of various anode materials for high performance LIBs by synergistically structural, electronic and ionic modulations.

A convenient and scalable in situ chemical vapor deposition (CVD) method is developed for one-step fabrication of sandwiched graphene sheets which were filled with yolk–shell γ-Fe2O3 nanoparticles encapsulated with graphene shells (YS-γ-Fe2O3@G-GS). Such a unique architecture can be applied to produce an excellent lithium ion battery (LIB) anode. As a result, long-term cycling stability at high rates (a high capacity of 663.7 mA h g−1 is achieved at 2 A g−1 and maintained at approximately 96.6% even after 1500 cycles) and superior rate capability (1173 mA h g−1 at 0.1C, 989 mA h g−1 at 0.2C, 827 mA h g−1 at 0.5C, 737 mA h g−1 at 1C, 574 mA h g−1 at 2C, 443 mA h g−1 at 5C, and 350 mA h g−1 at 10C; 1C = 1 A g−1) can be obtained when YS-γ-Fe2O3@G-GS is used as an LIB anode. As far as we know, this is the best rate capacity and longest cycle life ever reported for an Fe2O3-based LIB anode.

Discrete, homogenous and ultrasmall (mostly 2–4 nm) L10-ordered fct FePt nanoparticles encapsulated in well-graphitized thin carbon shells have been prepared by a one-step solid-phase synthesis technique, which can be applied for the production of a number of metal alloy nanoparticles encapsulated in carbon shells. The as-synthesized FePt@C nanoparticles of size 2.1 ± 0.4 nm present superparamagnetic properties at room temperature. The 3.3 ± 0.6 nm size FePt@C nanoparticles have a high coercivity, up to 4.56 kOe at room temperature, and superior chemical stability in a high concentration HCl (10 M) solution. Furthermore, these nanoparticles functionalized non-covalently by phospholipid-poly(ethylene)glycol show biocompatibility with the tested cells (mouse macrophage and mouse L929 fibroblasts cells) in all test concentrations (0.025–0.2 mg mL−1).

A high-quality ultrathin anatase TiO2 nanosheet (ANT)/reduced graphene oxide (RGO) composite is successfully prepared by a simple one-step hydrothermal synthetic route. The unique 2-D integrative features and mesoporous characteristic of the ultrathin ATN/RGO composite with a large surface area and outstanding stability are very favorable for lithium storage. A high initial discharge capacity (256.4 mA h g−1 at 0.2C), a high initial Coulombic efficiency (86%), a high rate capability (225.7, 202, 183, 157, 118 and 88.3 mA h g−1 at 0.5, 1, 2, 5, 10, and 20C, respectively, 1C = 167.5 mA h g−1), and a superior cyclability (174.2 mA h g−1 after 200 cycles at 1C and 112.9 mA h g−1 after 260 cycles at 10C) are achieved by using the ultrathin ATN/RGO composite as an anode material for lithium-ion-batteries. A detailed comparative study of the electrochemical properties of P25 nanoparticles, ATNs, ATN/RGO, and ultrathin ATN/RGO composites reveals that the significantly enhanced lithium storage capability is attributed to the ultrathin TiO2 nanosheets with short ion diffusion paths facilitating Li+ insertion/extraction, RGO conductive supports for fast electron transport, and the extra Li storage at the RGO/TiO2 interface.

Three-dimensional (3D) hierarchical porous carbons (indicated with 3D HPCs) were synthesized via a simple one-pot method using the self-assembly of various water-soluble NaX salts (X: Cl−, CO32−, SiO32−) as structure-directing templates. By controlling crystallization and assembly of multi-scale salts via a freeze-drying process, 3D porous carbon networks with tailored pore size distribution have been generated by calcining the salts/glucose self-assembly followed by removing the 3D self-assembly of NaX salts via simple water washing. When their applications were evaluated for supercapacitor electrodes as an example, the as-constructed 3D HPCs with large surface area, high electron conductivity, facile electrolyte penetration and robust structure exhibited excellent capacitive performance, namely, high specific capacitance (320 F g−1 at 0.5 A g−1), outstanding high rate capacitance retention (126 F g−1 at 200 A g−1), and superior specific capacitance retention ability (nearly no discharge capacity decay between 1000 and 10000 continuous charge–discharge cycles at a high current density of 5 A g−1). Based on our soluble salt self-assembly-assisted synthesis concept, it was revealed that salts in seawater are also very suitable for low-cost and scalable synthesis of 3D HPCs with good capacitive performance, which pave the way for advanced utilization of seawater.

A facile and scalable strategy for the synthesis of discrete, homogeneous and small (mostly 5–15 nm) Fe3O4 nanocrystals embedded in a partially graphitized porous carbon matrix was developed, which involved the simple mixing of a metal precursor (Fe(NO3)3·9H2O), a carbon precursor (C6H8O7), and a dispersant (NaCl) in an aqueous solution followed by calcination at 600 °C for 2 h under Ar. As the anode materials for lithium-ion batteries, the Fe3O4/carbon composite with 55.24 wt% Fe3O4 exhibited superior electrochemical performances, such as high reversible lithium storage capacity (834 mA h g−1 at 1 C after 60 cycles, 1 C = 924 mA g−1), high Coulombic efficiency (∼100%), excellent cycling stability, and superior rate capability (588 mA h g−1 at 5 C and 382 mA h g−1 at 10 C). These excellent electrochemical performances could be attributed to the robust porous carbon matrix with a partially graphitized structure for embedding a mass of small Fe3O4 nanocrystals, which not only provided excellent electronic conductivity, short transportation length for both lithium ions and electrons, and enough elastic buffer space to accommodate volume changes upon lithium insertion/extraction, but also could effectively avoid agglomeration of the Fe3O4 nanocrystals and maintain the structural integrity of the electrode during the charge–discharge process. It is believed that the Fe3O4/carbon composite synthesized by the current method is a promising anode material for high energy and power density lithium-ion batteries.