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Three-dimensional (3D) nanostructures are commonly endowed with numerous active sites, large specific surface area, and good mechanical strength, which make them as an efficient candidate for energy storage and conversion. Herein, by considering the advantages of 3D nanostructures, we successfully fabricated carbon-coated nickel sulfide on a nickel foam (C@NS@NF) with a unique 3D treelike superstructure via a two-step hydrothermal process. By virtue of its hierarchical superstructures, 3D treelike architecture, and carbon shell encapsulation, the as-fabricated carbon-coated Ni3S2 can be directly served as binder-free bifunctional electrodes for supercapacitor and hydrogen evolution reaction, where high specific areal capacitance (6.086 F cm-2 at 10 mA cm-2) for supercapacitors and low overpotential (92 mV at 10 mA cm-2) for the electrocatalyst have been demonstrated. These inspiring results of this material make it as a potential candidate for energy storage and conversion.

Three-dimensional (3D) binary oxides with hierarchical porous nanostructures are attracting increasing attentions as electrode materials in energy storage and conversion systems because of their structural superiority which not only create desired electronic and ion transport channels but also possess better structural mechanical stability. Herein, unusual 3D hierarchical MnCo2O4 porous dumbbells have been synthesized by a facile solvothermal method combined with a following heat treatment in air. The as-obtained MnCo2O4 dumbbells are composed of tightly stacked nanorods and show a large specific surface area of 41.30 m2 g–1 with a pore size distribution of 2–10 nm. As an anode material for lithium-ion batteries (LIBs), the MnCo2O4 dumbbell electrode exhibits high reversible capacity and good rate capability, where a stable reversible capacity of 955 mA h g–1 can be maintained after 180 cycles at 200 mA g–1. Even at a high current density of 2000 mA g–1, the electrode can still deliver a specific capacity...

Two-dimensional transition-metal dichalcogenides (TMDs) nanosheets have attracted tremendous research interest. Engineering the structure of MoS2 may result in desirable performance for energy applications. In this work, oxygen-incorporated MoS2 nanosheets with expanded interlayers have been synthesized by a solvothermal reaction. The oxygen-incorporated MoS2 nanosheets with rich defects demonstrate excellent hydrogen evolution reaction activity with a small Tafel slope of 42 mV decade–1 as well as excellent long-term stability. Interestingly, a large expanded ∼8.40 A interlayer of (002) faces can be achieved by controlling the reaction time. This material also shows excellent long-term cycling stability (up to 20 000 cycles) as well as high specific capacitance for pseudocapacitors. We believe that the structural modification strategy can be applied for other TMDs to further optimize the performance for various applications.

Olivine-type structured LiMnPO4 has been extensively studied as a high-energy density cathode material for lithium-ion batteries. However, preparation of high-performance LiMnPO4 is still a large obstacle due to its intrinsically sluggish electrochemical kinetics. Recently, making the composites from both active components has been proven to be a good proposal to improve the electrochemical properties of cathode materials. The composite materials can combine the advantages of each phase and improve the comprehensive properties. Herein, a LiMnPO4·Li3V2(PO4)3/C composite with interconnected nanorods and nanoflakes has been synthesized via a one-pot, solid-state reaction in molten hydrocarbon, where the oleic acid functions as a surfactant. With a highly uniform hybrid architecture, conductive carbon coating, and mutual cross-doping, the LiMnPO4·Li3V2(PO4)3/C composite manifests high capacity, good rate capability, and excellent cyclic stability in lithium-ion batteries. The composite electrodes deliver a hi...

Carbon-based nanocomposites have been extensively studied in energy storage and conversion systems because of their superior electrochemical performance. However, the majority of metal oxides are grown on the surface of carbonaceous material. Herein, we report a different strategy of constructing V2O5 within the metal organic framework derived carbonaceous dodecahedrons. Vanadium precursor is absorbed into the porous dodecahedron-shaped carbon framework first and then in situ converted into V2O5 within the carbonaceous framework in the annealing process in air. As cathode materials for lithium ion batteries, the porous V2O5@C composites exhibit enhanced electrochemical performance, due to the synergistic effect of V2O5 and carbon composite.

Sodium vanadium oxide (Na1.25V3O8) nanobelts have been successfully prepared by a facile sol-gel route with subsequent calcination. The morphologies and the crystallinity of the as-prepared Na1.25V3O8 nanobelts can be easily controlled by the calcination temperatures. As cathode materials for lithium ion batteries, the Na1.25V3O8 nanobelts synthesized at 400 °C exhibit a relatively high specific discharge capacity of 225 mA h g(-1) and excellent stability at 100 mA g(-1). The nanobelt-structured electrode can retain 94% of the initial capacity even after 450 cycles at the current density of 200 mA g(-1). The good electrochemical performance is attributed to their nanosized thickness and good crystallinity. The superior electrochemical performance demonstrates the Na1.25V3O8 nanobelts are promising cathode materials for secondary lithium batteries.

Hierarchical three-dimensional (3D) vanadium oxide microstructures, including urchin-like microflowers, nanohorn-structured microspheres, nanosheet-assembled microflowers, and nanosheets bundles, are successfully synthesized by a versatile template-free solvothermal method. It is found that the concentration of the precursor (VOC(2)O(4)) solution has a significant effect on the morphologies of the products. As an example, the time-dependent phase and morphology evolution for the urchin-like vanadium oxide microflowers has been investigated in detail. Urchin-like VO(2) microflowers can be self-assembled within 2 h without using any surfactants. After calcination, the VO(2) microflowers can be easily transformed to urchin-like V(2)O(5) microstructures. The as-obtained V(2)O(5) microflowers are highly porous with a specific surface area of 33.64 m(2) g(-1). When evaluated as a cathode material for lithium-ion batteries, the V(2)O(5) sample delivers very high specific discharge capacity of 267 mA h g(-1) at a current density of 300 mA g(-1). Further, it also exhibits improved cycling stability. The excellent electrochemical performance is attributed to multiple advantageous structural features, including the nanosized building blocks, high porosity, and the 3D hierarchical microstructures.