It becomes increasingly important to develop integrated systems with the aim of achieving maximum functionality for the state-of-the-art electronic devices. Here, a flexible integrated electrical cable is reported by incorporating biomaterials based fiber supercapacitors into a resistor–capacitor circuit. In this unique integrated configuration, the fiber electrodes are alternately winded along the twisted electric wires, which worked not only as scaffolding to support and strengthen the slight electrodes but also as separators to spatially confine them to avoid short circuit. It exhibits excellent electrochemical performance comparable to conventional transition metal compounds based cells, and can especially realize sophisticated applications in synchronous energy transmission and storage, presenting a new member for the integrated energy storage system family.

Shape-dependent catalysis and sensing behaviours are primarily focused on nanocrystals enclosed by low-index facets, especially the three basic facets ({100}, {111}, and {110}). Several novel strategies have recently exploded by tailoring the original nanocrystals to greatly improve the catalysis and sensing performances. In this Review, we firstly introduce the synthesis of a variety of Cu₂O nanocrystals, including the three basic Cu₂O nanocrystals (cubes, octahedra and rhombic dodecahedra, enclosed by the {100}, {111}, and {110} facets, respectively), and Cu₂O nanocrystals enclosed by high-index planes. We then discuss in detail the three main facet-controlled synthetic strategies (deposition, etching and templating) to fabricate Cu₂O-based nanocrystals with heterogeneous, etched, or hollow structures, including a number of important concepts involved in those facet-controlled routes, such as the selective adsorption of capping agents for protecting special facets, and the impacts of surface energy and active sites on reaction activity trends. Finally, we highlight the facet-dependent properties of the Cu₂O and Cu₂O-based nanocrystals for applications in photocatalysis, gas catalysis, organocatalysis and sensing, as well as the relationship between their structures and properties. We also summarize and comment upon future facet-related directions.

A novel porous manganese sulfide/graphene composite was prepared by a simple in situ solvothermal approach. These mesoporous manganese sulfide sub-microspheres with an average diameter of 700 nm were anchored homogeneously onto graphene nanosheets. Such a special microstructure not only effectively alleviates the mechanical strain of the electrode upon lithiation/delithiation, but it also improves contact between the electrode materials and the electrolyte. As a result, the composite exhibits a high Li-ion storage capacity and excellent cycling stability as an anode material for lithium-ion batteries. At a current of 50 mA h g⁻¹, the material delivers a reversible capacity up to 1231 mA h g⁻¹; at a current density of 0.2 A g⁻¹, the material still retains a reversible capacity of 735 mA h g⁻¹ after 300 cycles.

In spite of potential favorable electrochemical properties, reports of amorphous materials as catalysts for water oxidation are quite few. Highly efficient amorphous Ni−Zn double hydroxide nanocages as electrocatalysts for oxygen evolution reaction (OER) were prepared through a co-precipitate method. We investigated the influence of composition on electrocatalytic activity experimentally. Ni_2.7Zn(OH)_x turned out to be the optimal composition of these samples, which exhibited an OER onset overpotential as low as 0.20 V in 1 m KOH electrolyte solution. In addition, Ni_2.7Zn(OH)_x could reach a current density of 10 A g¹ at an overpotential of approximately 0.20 V. Such high mass activity should take advantage of the unique amorphous hollow nanostructure of our sample, which can provide substantial exposure of surface active atoms for remarkable catalytic activity. This amorphous Ni−Zn double hydroxide material was found to be a remarkable OER electrocatalyst and exhibited higher electrocatalytic activity than commercial IrO₂.

White-fungus-like NiS_x microspheres have been synthesized on a large scale by using a simple hydrothermal method. The influence of the reaction time and the surfactant on the final products was investigated, and the formation mechanism was discussed. The synthesized white-fungus-like NiS_x microspheres were used firstly as fillers in the fabrication of NiS_x/polyvinylidene fluoride (PVDF) composites. Relationships between the loadings of the NiS_x and wave-absorption properties of the composites were analyzed. The loss mechanisms of NiS_x/PVDF with different loadings were also discussed according to their dielectric and magnetic behaviors.

Reduced graphene oxide (RGO)/Co₃O₄ nanohybrid particles, composed of reduced graphite oxide and Co₃O₄ particles, have been fabricated by an in situ growth method under mild wet-chemical conditions (140 °C). A series of characterization results indicate that the as-prepared Co₃O₄ particles with relatively uniform sizes are embedded in RGO layers to form unique core–shell nanostructures. The RGO/Co₃O₄/poly(vinylidene fluoride) composite was found to possess excellent absorption properties. Owing to the effect of the negative permeability, the position of the absorption peaks remains at the same frequency at different thicknesses without shifting to lower frequencies. For the composites with a filler loading of 10 wt %, the maximum peaks can reach −25.05 dB at 11.6 GHz with a thickness of 4.0 mm. These enhanced microwave absorbing properties can be explained based on the structures of the nanohybrid particles.

The assembly of inorganic nanoparticles (NPs) into 3D superstructures with defined morphologies is of particular interest. A novel strategy that is based on recrystallization-induced self-assembly (RISA) for the construction of 3D Cu₂O superstructures and employs Cu₂O mesoporous spheres with diameters of approximately 300 nm as the building blocks has now been developed. Balancing the hydrolysis and recrystallization rates of the CuCl precursors through precisely adjusting the experimental parameters was key to success. Furthermore, the geometry of the superstructures can be tuned to obtain either cubes or tetrahedra and was shown to be dependent on the growth behavior of bulk CuCl. The overall strategy extends the applicability of recrystallization-based processes for the guided construction of assemblies and offers unique insights for assembling larger particles into complicated 3D superstructures.

AgBr nanocrystals, evolving from plates through truncated cubes and finally to regular cubes, corresponding to a progressive shrinkage of exposed {1 1 1} facets and enlargement of exposed {1 0 0} facets, were successfully prepared by facile ion-exchange reactions under the synergistic effects of polyvinylpyrrolidone and NH₃⋅ H₂O. An investigation of the growth mechanism revealed that polyvinylpyrrolidone can selectively adsorb on the {1 1 1} facets of AgBr nanocrystals, whereas NH₃⋅H₂O not only forms a [Ag(NH₃)₂]⁺ complex that slows the rates of ion-exchange reactions, but may also prefer to adsorb on {1 0 0} facets. Studies of their photocatalytic properties showed that the as-prepared AgBr nanocrystals exhibited facet-dependent photocatalytic properties. The {1 1 1}-dominated AgBr nanoplates exhibited the highest photocatalytic activities, and the photodegradation rate of methyl orange dyes over them was 3 times faster than over AgBr nanocubes that expose {1 0 0} facets. Surface atomic models and DFT calculations indicate that the {1 1 1} facets have more dangling bonds and a higher surface energy than the {1 0 0} facets, which substantiate the facet-dependent photocatalytic properties. Therefore, our work not only provides a novel method to prepare regular AgBr nanocrystals, but also demonstrates that the shape and exposed facets have important influence on their photocatalytic activities.

A facile and environmentally friendly hydrothermal approach has been employed to synthesize size-controllable quasi-cubic α-Fe₂O₃ nanocrystals by using an aqueous solution of FeCl₃ without any alkaline materials and stabilizing agent. The as-prepared products were carefully characterized and the growth mechanism is also discussed. This hydrothermal synthesis of such quasi-cubic structures implies a simple and low-cost route to prepare monodisperse nanomaterials on a large scale. The size-controllable synthesis of α-Fe₂O₃ is the first achieved successfully from 80 nm to 2 μm with constant structures. The synthesized α-Fe₂O₃ materials have different optical properties and stabilities in water, which are caused by the change of their band-gap energy and specific surface areas. Finally, the dielectric properties of synthesized α-Fe₂O₃ cubes were also investigated, and the differences caused by the particle sizes are discussed.

As the properties of nanomaterials are strongly dependent on their size, shape and nanostructures, probing the relations between macro-properties and nanostructures is challenging for nanoscientists. Herein, we deliberately chose three types of Ni(OH)₂ with hexagonal, truncated trigonal, and trigonal hourglass-like nanostructures, respectively, as the electrode modifier to demonstrate the correlation between the nanostructures and their electrocatalytic performance towards L-histidine. It was found that the hexagonal hourglass-like Ni(OH)₂ sample had the best electrocatalytic activity, which can be understood by a cooperative mechanism: on one hand, the hexagonal sample possesses the largest specific surface area and the tidiest nanostructure, resulting in the most orderly packing on the electrode surface; on the other hand, its internal structure with the most stacking faults would generate a lot of unstable protons, leading to an enhanced electronic conductivity. The findings are important because they provide a clue for materials design and engineering to meet a specific requirement for electrocatalysis of L-histidine, possibly even for other biomolecules. In addition, the hexagonal Ni(OH)₂-based biosensor shows excellent sensitivity and selectivity in the determination of L-histidine and offers a promising feature for the analytical application in real biological samples.

A series of CuS nanostructures were synthesized by a simple wet chemical method on a large scale in the presence of cetyltrimethylammonium bromide at low temperature. Three typical samples were selected to study the relationship between the morphologies and resulting physical properties. The optical properties of CuS hierarchical structures were investigated by UV/Vis and Raman spectroscopy and the excellent photocatalytic performance was also evaluated by measuring the decomposition rate of methylene blue under natural light. As an absorber, the selected CuS nanostructures possess excellent microwave absorbing properties. When the thickness of the absorber is 3.5 mm, the minimum reflection loss can reach −76.4 dB at 12.64 GHz. The enhanced photocatalytic performance and microwave absorbing properties were also explained based on morphologies of the nanostructures.

Novel α-MnS hollow spheres (MHSs) have been fabricated successfully by a one-pot template-free solvothermal method. The as-synthesized α-MnS spheres have diameters of about 3–5 μm and porous shells of thickness about 0.5 μm composed of numerous nanocrystals. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption. Time-dependent morphology evolution suggested that transformation of chemical components and Ostwald ripening play vital roles for these hollow structures with a porous shell. The possible formation mechanism for the fabrication of MHSs is proposed. Meanwhile, MHS–reduced graphene oxide (RGO) hybrids have been prepared in the presence of graphene oxide (GO) by using the same procedure. The amount of GO can affect the morphology of α-MnS crystals in hybrids. The microwave absorption and lithium storage properties of the pure MHSs and MHS–RGO hybrids were studied in detail. Compared with pristine MHSs, the MHS–RGO hybrids possess remarkably enhanced microwave absorption and lithium storage properties. The enhanced microwave absorbing and electrochemical properties are also explained.

Fe₃O₄ nanocrystals with narrow particle size distribution (10–15 nm) were produced in high yield by using a simple solution-phase method at room temperature. In this approach, the iron oxide nanocrystals can be continually prepared through controlling the pH value of the solution. The as-synthesized Fe₃O₄ nanoparticles are single-crystalline and exhibit high saturation magnetization. New adsorbents of Fe₃O₄ nanocrystals immobilized on bacterial cellulose (FNBC) were prepared by a simple blending method in the hope of removing heavy metal ions from aqueous solutions. The FNBC showed significantly higher affinity for removing Cd²⁺ compared to BC. In addition, the effect of characteristic parameters such as pH value, adsorption time by simulating the adsorptive kinetics, and adsorptive isotherms were also investigated.

Chemical enhancement in surface-enhanced Raman scattering (SERS) of pyrazine adsorbed on Au–Pd nanoclusters is investigated by using density functional theory. Changing Pd content in the bimetallic clusters enables modulation of the direct chemical interactions between the pyrazine and the clusters. The magnitude of chemical enhancement is correlated well with the induced polarizability for the complexes with low Pd content, which fails for the complexes with high Pd content. Furthermore, the dependence of chemical enhancement on cluster size and coupling is also described by the induced polarizability. Additionally, the chemical enhancement in the cluster–molecule–cluster junction is found to account for as much as 10³, which suggests that a chemical mechanism might be more important than previously believed, in particular for Au–Pd bimetallic nanoparticle aggregates.

Highly reproducible surface-enhanced Raman scattering (SERS) spectra are obtained on the surface of SnO₂ octahedral nanoparticles. The spot-to-spot SERS signals show a relative standard deviation (RSD) consistently below 20 % in the intensity of the main Raman peaks of 4-mercaptobenzoic acid (4-MBA) and 4-nitrobenzenethiol (4-NBT), indicating good spatial uniformity and reproducibility. The SERS signals are believed to mainly originate from a charge-transfer (CT) mechanism. Time-dependent density functional theory (TD-DFT) is used to simulate the SERS spectrum and interpret the chemical enhancement mechanism in the experiment. The research extends the application of SERS and also establishes a new uniform SERS substrate.

We present a detailed analysis of the surface-enhanced Raman scattering (SERS) of adenine and 2′-deoxyadenosine 5′-monophosphate (dAMP) adsorbed on an Ag₂₀ cluster by using density functional theory. Calculated Raman spectra show that spectral features of all complexes depend greatly on adsorption sites of adenine and dAMP. The complexes consisting of adenine adsorbed on the Ag₂₀ cluster through N3 reproduce the measured SERS spectra in silver colloids, and thus demonstrated that adenine interacts with the silver surface via N3. We also investigate the SERS spectrum of adenine at the junction between two Ag₂₀ clusters and demonstrate that adenine can bind to the clusters through N3 and the external amino group, while dAMP can be adsorbed on the cluster in an end-on orientation with the ribose and phosphate groups near to or away from the silver cluster. In contrast to the adenine–Ag₂₀ complexes, the dAMP–Ag₂₀ complexes produce new and strong bands in the low- or high-wavenumber region of the Raman spectra, due to vibrations of the ribose and phosphate groups. Furthermore, the spectrum of dAMP bound to the Ag₂₀ cluster via N7 approaches the experimental SERS spectra on silver colloids.

Peapodlike Ni/Ni₃S₂ chains of about 30 nm in outer diameter, with Ni cores of 10–15 nm, can be synthesized by a sacrificial template route. The Ni₃S₂ shell exhibits paramagnetic properties with a mass susceptibility of χ ≈ 5 × 10⁻⁵ emu (gOe)⁻¹, while the ferromagnetic Ni cores show a superparamagnetic behavior with a blocking temperature of T_B ≈ 130 K. The shape anisotropy of the chainlike structure is determined as 5.0 × 10⁴ J·m⁻³, which is larger than the bulk magnetocrystalline anisotropy by one order of magnitude. The demagnetization factor is determined as ΔN = 0.29. The sample provides an ideal structure for studying the magnetization reversal property by the chain-of-sphere model. The observations on the formation of the peapod structure verify a growth mechanism of the nanoscale Kirkendall effect. Based on the preparation of peapod chains, a series of nickel sulfide hollow chains with average diameters of 25, 50, and 100 nm are fabricated. In addition, the phase transition for hollow chains from Ni₃S₂ to NiS is studied.

Single-crystalline ZnO nanowire bundles have been synthesized in large-scale by an improved microemulsion method in the presence of excessive hydrate hydrazine and dodecyl benzene sulfonic acid sodium salt (DBS) in xylene. The product is characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). The result shows that the bundle is composed by many oriented single-crystalline ZnO nanowires with a length of about 1 μm and a diameter of about 20–30 nm. The influence of DBS, hydrazine and the reaction time on the morphology of final product and the formation mechanism of such nanostructures were discussed; the application in the dielectric composites is also studied.

Direct radical additions of ethers to terminal alkynes were investigated by using Me₂Zn/O₂ as radical initiator to afford 2-vinyl ether derivatives with high E-selectivity, while reversed E/Z selectivity is obtained with Et₃B/O₂. Two competitive pathways are suggested for the formation of vinyl radical B: zinc-radical exchange (route a) followed by protonation provides E-configuration products exclusively through Zn(II) complexation. Hydrogen abstraction by vinyl radicals (route b) yields mainly Z isomers.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)