•TiO2/Cu composites were synthesized by an in-situ molecular-level mixing method successfully.•The composites possess well-balanced mechanical properties and electron conductivity.•The deformational behavior and strengthening mechanism were discussed.In this work, Cu matrix composites reinforced with rutile-TiO2 nanoparticles were fabricated by a facile in-situ method, which involved the in-situ synthesis of TiO2-Cu composite powders by molecular-level mixing process and subsequent vacuum hot-pressing sintering of the as-obtained composite powders, leading to dense bulk composites with homogeneously distributed TiO2 nanoparticles. The influences of in-situ route on the microstructures, TiO2 distribution and mechanical properties of the composites were investigated. The results showed that the composite with 1.72 vol% TiO2 not only exhibited a high yield strength of 290 MPa which is about 1.6 times larger than that of pure Cu (110 MPa), but also possessed a high fracture elongation of 32% and an outstanding electrical conductivity of 97% IACS, indicating the as-obtained TiO2/Cu composites possessing well-balanced mechanical properties and electron conductivity. Moreover, the strengthening mechanism of TiO2 nanoparticles for the Cu matrix composites was analyzed based on the experimental results.Download high-res image (92KB)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.

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.

A new strategy for the one-step synthesis of a 0D SnCo nanoparticles-1D carbon nanotubes-3D hollow carbon submicrocube cluster (denoted as SnCo@CNT-3DC) hierarchical nanostructured material was developed via a simple chemical vapor deposition (CVD) process with the assistance of a water-soluble salt (NaCl). The adopted NaCl not only acted as a cubic template for inducing the formation of the 3D hollow carbon submicrocube cluster but also provides a substrate for the SnCo catalysts impregnation and CNT growth, ultimately leading to the successful construction of the unique 0D-1D-3D structured SnCo@CNT-3DC during the CVD of C2H2. When utilized as a lithium-ion battery anode, the SnCo@CNT-3DC composite electrode demonstrated an excellent rate performance and cycling stability for Li-ion storage. Specifically, an impressive reversible capacity of 826 mA h g−1 after 100 cycles at 0.1 A g−1 and a high rate capacity of 278 mA h g−1 even after 1000 cycles at 5 A g−1 were achieved. This remarkable electrochemical performance could be ascribed to the unique hierarchical nanostructure of SnCo@CNT-3DC, which guarantees a deep permeation of electrolytes and a shortened lithium salt diffusion pathway in the solid phase as well as numerous hyperchannels for electron transfer.

SnO2 is considered a promising anode candidate for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), but suffers from the low electrical conductivity and severe volume variation during repetitive cycling. To circumvent these issues, we developed novel interconnected sandwiched carbon-coated hollow nanostructures, i.e., carbon–shell/SnO2–nanocrystal–layer/hollow–carbon–core (C@SnO2@C HNSs), in which ultrasmall SnO2 nanocrystals (2–5 nm) were tightly confined between the carbon shell and the hollow carbon core. Such a unique structure can not only protect the active materials from direct exposure to the electrolyte as well as restrain the migration and pulverization of the SnO2, but also offer rich void space for buffering the volume changes and complement the electron conductivity of the active materials, thus achieving remarkably enhanced electrical conductivity and structural integrity of the whole electrode. As a consequence, this C@SnO2@C HNS electrode exhibited an extremely outstanding long-life high-rate cycling stability for both LIB and SIB anodes, such as only 8% capacity loss after 1000 cycles at 10 A g−1 for LIB anode and only 10% capacity loss after 3000 cycles at 4.6 A g−1 for SIB anodes. As far as we know, this is the best high-rate cycle performance ever reported for SnO2-based SIB anodes.

Proper hybridization of different kinds of materials into tailored structures is a highly effective way to fabricate advanced anode materials for sodium ion batteries. In this work, mulberry-like Sn2Nb2O7/SnO2 nanoparticles (≈40 nm) homogeneously anchored on 3D carbon networks (indicated with M-Sn2Nb2O7/SnO2@3DC) were prepared through a facile one-step high temperature calcination technique. In the constructed architecture, Sn-based materials with high specific capacity, Nb-based materials with excellent structural stability and 3D carbon networks with high electron conductivity were well integrated into a smart system. The 3D carbon networks not only act as a buffer material to prevent pulverization, but also serve as a conductive matrix, while the in situ formed amorphous NaxNb2O5 substrate from Sn2Nb2O7 can restrain the volume variation to prevent Sn from aggregation and pulverization during cycling. This unique “self-buffering” effect can remarkably enhance the structural integrity of the electrode. As a result, when tested as a sodium ion battery anode, the as-synthesized hybrid exhibited relatively high reversible capacity (300 mA h g−1 at the current density of 100 mA g−1), outstanding high-rate capability (119 mA h g−1 even at the high current density of 10 A g−1) and extremely long cycling stability (130 mA h g−1 at the current density of 5.0 A g−1 for 5000 cycles). Such excellent electrochemical performance demonstrates the potential use of the Sn2Nb2O7/SnO2@3D carbon composite as an anode material for high-performance sodium-ion batteries.

Graphene has attracted a lot of interest to be used as reinforcement in Aluminum matrix composites (AMCs) on account of its superior mechanical properties. However, the most serious and challenging issues in graphene-reinforced AMCs are that reinforcements are quite difficult to disperse uniformly in metal matrix and ensure intimate interfacial bonding simultaneously. In this work, an ultrafine Ni nanoparticles (NPs)-decorated graphene hybrid (indicated with Ni-NPs@GNP) was firstly synthesized by an in-situ chemical vapor deposition method to improve the wettability between metal and carbon nanophase, then the Ni-NPs@GNP/6061Al composite powders were obtained by dispersing the Ni-NPs@GNP into 6061Al alloy particles via a short time intermittent ball milling process. Finally, the Ni-NPs@GNP/6061Al bulk composites were fabricated through hot-pressing sintering of the composite powders. It was demonstrated that good dispersion of reinforcements was achieved in the Ni-NPs@GNP/6061Al composite coupled with remarkably enhanced interfacial bonding by introducing Ni NPs on the graphene, which resulted in the formation of Al3Ni intermetallic at the interface and thus improved the interfacial adhesion between 6061Al and graphene. As a result, the Ni-NPs@GNP/6061Al composite with 0.7 wt% reinforcement exhibited much enhanced mechanical properties, namely, a high yield strength of 140 MPa together with a tensile strength of 213 MPa can be achieved, which were 75% and 30% higher than that of the monolithic 6061Al, respectively. This work provides an inspiring strategy for fabricating 6061Al composites with adjustable mechanical properties as well as controllable interfacial bonding.

Constructing a 3D porous architecture from 2D MoS2 nano-building blocks has been considered as a promising approach to prevent restacking and thus achieve superior properties in energy conversion and storage, catalysis, sensors, and so on. In this work, a novel salt (NaCl) template-assisted solid-phase synthesis strategy is developed to fabricate a new type of MoS2 with a robust 3D honeycomb-like structure without the necessity to use a solution reaction. As a demonstration of structural advantages, the 3D honeycomb-structured MoS2 with a highly crystalline architecture and intimate interfacial bonding between adjacent MoS2 walls is utilized as a lithium-ion battery anode, exhibiting an unprecedented initial coulombic efficiency (∼93.5%), large specific capacity, high rate capability and excellent cycle stability.

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 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.

Metallic Sn has triggered significant research efforts as a lithium ion battery anode due to its high theoretical capacity and low-cost. However, the structural damage induced by the severe volume change of Sn and the continuous interfacial reaction due to the electrolyte remain two major challenges to hinder the practical applications of Sn-based anodes. In this work, we report the fabrication of a novel 3D composite architecture that is constructed by flexible graphene/Sn sandwich nanosheets synthesized by an in situ catalytic synthesis strategy, which relies on in situ formation and spatial entrapment of active Sn nanoparticles (NPs) inside the simultaneously catalytically formed 3D porous graphene. Such a unique architecture not only provides robust protection against the aggregation and volume changes of Sn NPs, and thus effectively avoids the direct contact between entrapped Sn and the electrolyte and enables the interfacial and structural stabilization of entrapped Sn NPs during cycling, but also ensures highly favorable three dimensional transport kinetics for both electrons and lithium ions in the whole electrode. As a result, this 3D composite anode exhibits very high reversible capacity, superior rate capability, and extremely excellent cycle stability even at high rates (650 mA h g−1 at 2 A g−1 over 500 cycles).

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.

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.

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;

A chain-like carbon nanostructure, which we call as carbon nano-chains (CNCs), was synthesized through chemical vapor deposition (CVD). The influence of growth conditions (such as growth temperature, time and gas ratio) during CVD process on the carbon structures and the growth mechanism of the CNCs were investigated. To explore the potential application as electrode materials of supercapacitors, the electrochemical performances of the CNCs and the CNCs activated with KOH have been tested. The results indicated that the original CNCs exhibit relatively high specific surface area, high purity and regular framework, and favor growth at a moderate temperature and mild gas ratio. After activation, the CNCs have much improved specific surface area and porous structure. The electrochemical performance investigations showed that the activated CNCs have a power density of 159.6 kW kg−1 and an energy density of 15.5 W h kg−1, as well as excellent cycle stability, which is very superior to the original CNCs. This simple and low-cost preparation process and the superb electrochemical performance suggest great potential applications of activated CNCs in supercapacitors.

Carbon-coated Ni3Sn2 nanoparticles uniformly embedded in two-dimensional porous carbon nanosheets (2D Ni3Sn2@C@PGC) as superior lithium ion battery anode material were fabricated by a facile and scalable method, which involves in situ synthesis of 2D Ni@C@PGC and chemical vapor transformation processes from 2D Ni@C@PGC to Ni3Sn2@C@PGC. With the assistance of a water-soluble cubic NaCl template, 2D Ni@C@PGC was firstly in situ synthesized on the surface of NaCl particles. After vapor transformation with SnCl2, the Ni@C@PGC nanosheets were converted to Ni3Sn2@C@PGC, in which uniform Ni3Sn2 nanoparticles coated with conformal graphitized carbon layers were homogeneously embedded in 2D high-conducting carbon nanosheets with a thickness of about 30 nm. This unique 2D dual encapsulation structure with high porosity, high electronic conductivity, outstanding mechanical flexibility and short lithium ion diffusion pathway is favorable for lithium insertion and extraction during deep charge–discharge processes. As a result, the electrode fabricated using 2D Ni3Sn2@C@PGC as the anode and a lithium plate as the cathode exhibits a high reversible capacity up to 585.3 mA h g−1 at a current density of 0.2 C (1 C = 570 mA h g−1) after 100 cycles, a high rate capability (484, 424, 378, 314 and 188 mA h g−1 at 0.2, 0.5, 1, 2 and 5 C, respectively, 1 C = 570 mA h g−1), and superior cycling stability at a high rate (350.3 mA h g−1 at a rate of 1 C after 180 cycles).

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.

Two-dimensional (2D) porous graphitic carbon nanosheets (PGC nanosheets) as a high-rate anode material for lithium storage were synthesized by an easy, low-cost, green, and scalable strategy that involves the preparation of the PGC nanosheets with Fe and Fe3O4 nanoparticles embedded (indicated with (Fe&Fe3O4)@PGC nanosheets) using glucose as the carbon precursor, iron nitrate as the metal precursor, and a surface of sodium chloride as the template followed by the subsequent elimination of the Fe and Fe3O4 nanoparticles from the (Fe&Fe3O4)@PGC nanosheets by acid dissolution. The unique 2D integrative features and porous graphitic characteristic of the carbon nanosheets with high porosity, high electronic conductivity, and outstanding mechanical flexibility and stability are very favorable for the fast and steady transfer of electrons and ions. As a consequence, a very high reversible capacity of up to 722 mAh/g at a current density of 100 mA/g after 100 cycles, a high rate capability (535, 380, 200, and 115 mAh/g at 1, 10, 20, and 30 C, respectively, 1 C = 372 mA/g), and a superior cycling performance at an ultrahigh rate (112 mAh/g at 30 C after 570 charge–discharge cycles) are achieved by using these nanosheets as a lithium-ion-battery anode material.Keywords: carbon nanosheets; high-rate anode; lithium-ion battery; two dimensional;

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

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).

Hierarchical porous carbon (HPC) materials with graphitic structure, which exhibit an interesting highly developed three-dimensional porosity network of macropores in combination with meso-/micropores, have been synthesized by a water soluble template (NaCl) method combined with a metal-assisted catalytic technique at 850 °C. The soluble NaCl was used as a meso-porous and/or micro-porous structure-directing template, while glucose and Fe species were employed as carbon precursor and graphitization catalyst, respectively. Nitrogen adsorption–desorption analysis showed that with increasing the mole ratio between the metal precursor and the carbon precursor from 0.005 to 0.02, the Brunauer–Emmett–Teller surface area of the HPC samples varied from 498 to 253 m2/g.Highlights► Hierarchical porous carbon materials with graphitic structures have been synthesized. ► The soluble NaCl was used as a meso-porous and/or micro-porous structure-directing template. ► Glucose and Fe species were employed as carbon precursor and graphitization catalyst, respectively. ► The specific surface area was decreased with the increase of the content of metal precursor.

A chain-like carbon nanostructure, which we call as carbon nano-chains (CNCs), was synthesized through chemical vapor deposition (CVD). The influence of growth conditions (such as growth temperature, time and gas ratio) during CVD process on the carbon structures and the growth mechanism of the CNCs were investigated. To explore the potential application as electrode materials of supercapacitors, the electrochemical performances of the CNCs and the CNCs activated with KOH have been tested. The results indicated that the original CNCs exhibit relatively high specific surface area, high purity and regular framework, and favor growth at a moderate temperature and mild gas ratio. After activation, the CNCs have much improved specific surface area and porous structure. The electrochemical performance investigations showed that the activated CNCs have a power density of 159.6 kW kg−1 and an energy density of 15.5 W h kg−1, as well as excellent cycle stability, which is very superior to the original CNCs. This simple and low-cost preparation process and the superb electrochemical performance suggest great potential applications of activated CNCs in supercapacitors.

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 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.

Metallic Sn has triggered significant research efforts as a lithium ion battery anode due to its high theoretical capacity and low-cost. However, the structural damage induced by the severe volume change of Sn and the continuous interfacial reaction due to the electrolyte remain two major challenges to hinder the practical applications of Sn-based anodes. In this work, we report the fabrication of a novel 3D composite architecture that is constructed by flexible graphene/Sn sandwich nanosheets synthesized by an in situ catalytic synthesis strategy, which relies on in situ formation and spatial entrapment of active Sn nanoparticles (NPs) inside the simultaneously catalytically formed 3D porous graphene. Such a unique architecture not only provides robust protection against the aggregation and volume changes of Sn NPs, and thus effectively avoids the direct contact between entrapped Sn and the electrolyte and enables the interfacial and structural stabilization of entrapped Sn NPs during cycling, but also ensures highly favorable three dimensional transport kinetics for both electrons and lithium ions in the whole electrode. As a result, this 3D composite anode exhibits very high reversible capacity, superior rate capability, and extremely excellent cycle stability even at high rates (650 mA h g−1 at 2 A g−1 over 500 cycles).

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.

Constructing a 3D porous architecture from 2D MoS2 nano-building blocks has been considered as a promising approach to prevent restacking and thus achieve superior properties in energy conversion and storage, catalysis, sensors, and so on. In this work, a novel salt (NaCl) template-assisted solid-phase synthesis strategy is developed to fabricate a new type of MoS2 with a robust 3D honeycomb-like structure without the necessity to use a solution reaction. As a demonstration of structural advantages, the 3D honeycomb-structured MoS2 with a highly crystalline architecture and intimate interfacial bonding between adjacent MoS2 walls is utilized as a lithium-ion battery anode, exhibiting an unprecedented initial coulombic efficiency (∼93.5%), large specific capacity, high rate capability and excellent cycle stability.

Layered transition metal dichalcogenides (TMDs), such as MoS2, WS2, MoSe2, WSe2, etc., have received considerable interest recently due to their unique properties and fascinating applications. In this work, we proposed a NaCl template-assisted in situ chemical vapor deposition (CVD) strategy for synthesizing high-quality two-dimensional (2D) WS2, MoS2, MoSe2 and WSe2 nanosheets with a single-crystalline structure on a large scale. During the synthesis, 3D self-assembly of cubic NaCl particles can not only provide smooth surfaces to support the lateral growth, but also create a 2D confined space to restrict the thickening of TMD nanosheets, while the high-temperature annealing during the CVD process ensures high crystallinity and structural stability as well as remarkably promoting the conductivity of the TMD nanosheets. When evaluated as sodium-ion battery anodes, the representative WS2 nanosheets exhibited a high reversible specific capacity of 453 mA h g−1 at a current density of 0.1 A g−1, an excellent cycling performance and a greatly enhanced rate capability. The charge storage mechanism together with the microstructure evolution of WS2 nanosheets during the sodiation/disodiation processes is responsible for their superior sodium storage performance.

Proper hybridization of different kinds of materials into tailored structures is a highly effective way to fabricate advanced anode materials for sodium ion batteries. In this work, mulberry-like Sn2Nb2O7/SnO2 nanoparticles (≈40 nm) homogeneously anchored on 3D carbon networks (indicated with M-Sn2Nb2O7/SnO2@3DC) were prepared through a facile one-step high temperature calcination technique. In the constructed architecture, Sn-based materials with high specific capacity, Nb-based materials with excellent structural stability and 3D carbon networks with high electron conductivity were well integrated into a smart system. The 3D carbon networks not only act as a buffer material to prevent pulverization, but also serve as a conductive matrix, while the in situ formed amorphous NaxNb2O5 substrate from Sn2Nb2O7 can restrain the volume variation to prevent Sn from aggregation and pulverization during cycling. This unique “self-buffering” effect can remarkably enhance the structural integrity of the electrode. As a result, when tested as a sodium ion battery anode, the as-synthesized hybrid exhibited relatively high reversible capacity (300 mA h g−1 at the current density of 100 mA g−1), outstanding high-rate capability (119 mA h g−1 even at the high current density of 10 A g−1) and extremely long cycling stability (130 mA h g−1 at the current density of 5.0 A g−1 for 5000 cycles). Such excellent electrochemical performance demonstrates the potential use of the Sn2Nb2O7/SnO2@3D carbon composite as an anode material for high-performance sodium-ion batteries.

SnO2 is considered a promising anode candidate for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), but suffers from the low electrical conductivity and severe volume variation during repetitive cycling. To circumvent these issues, we developed novel interconnected sandwiched carbon-coated hollow nanostructures, i.e., carbon–shell/SnO2–nanocrystal–layer/hollow–carbon–core (C@SnO2@C HNSs), in which ultrasmall SnO2 nanocrystals (2–5 nm) were tightly confined between the carbon shell and the hollow carbon core. Such a unique structure can not only protect the active materials from direct exposure to the electrolyte as well as restrain the migration and pulverization of the SnO2, but also offer rich void space for buffering the volume changes and complement the electron conductivity of the active materials, thus achieving remarkably enhanced electrical conductivity and structural integrity of the whole electrode. As a consequence, this C@SnO2@C HNS electrode exhibited an extremely outstanding long-life high-rate cycling stability for both LIB and SIB anodes, such as only 8% capacity loss after 1000 cycles at 10 A g−1 for LIB anode and only 10% capacity loss after 3000 cycles at 4.6 A g−1 for SIB anodes. As far as we know, this is the best high-rate cycle performance ever reported for SnO2-based SIB anodes.