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Uniform V(2)O(5)· xH(2)O nanobelts with high aspect ratios and ultra-long V(2)O(5)· xH(2)O nanorolls with novel scroll-like structures were synthesized on a large scale by a simple hydrothermal growth route using NH(4)VO(3) as the raw material in the presence of different acids at 180 °C for 24 h. Their morphologies were observed by scanning electron microscopy (SEM). X-ray powder diffraction measurement and thermal gravimetric analysis revealed the composition of nanobelts and nanorolls to be V(2)O(5)·0.9H(2)O and V(2)O(5)·0.6H(2)O, respectively. The possible mechanisms of formation of the nanobelts and nanorolls were schematically elucidated based on the layered structure of vanadium pentoxide. In addition, corresponding anhydrous V(2)O(5) nanostructures with better crystallinity were obtained by calcining the precursors of V(2)O(5)·0.9H(2)O nanobelts or V(2)O(5)·0.6H(2)O nanorolls. Furthermore, we have investigated the electrochemical intercalation properties with Li(+) and the photocatalytic activities of the synthesized V(2)O(5)·0.9H(2)O nanobelts, V(2)O(5)·0.6H(2)O nanorolls and their corresponding post-annealing products. It was observed that the morphologies and compositions of the synthesized products had an evident influence on the electrochemical intercalation properties with Li(+) and photocatalytic activities.

Recently, the biomolecule-assisted synthesis method has been a new and promising focus in the preparation of various nanomaterials. But current works mainly focus on the synthesis of metal nanoparticles and nanowires using macro-biomolecules (e.g. virus, protein and DNA) as templates in the presence of a reducing agent. Beta-carotene, one of the most common bio-antioxidants, can be oxidized to form species with both hydrophilic and hydrophobic ends, which can provide an in situ soft template for the synthesis of nanomaterials. Herein, a simple beta-carotene-assisted method was developed for the first time to synthesize t-Se nanowires and nanoribbons with high crystallinity. We demonstrate that beta-carotene serves as not only the reducing agent, but also an in situ template in the preparation of Se one-dimensional nanostructures. It is found that the growth mechanism of Se nanomaterials is different from the familiar sphere–wire process. A novel flake-cracking mechanism is proposed. By this biomolecule-assisted route, Te one-dimensional nanostructures and Pd nanowires were also fabricated. The assisted-biomolecule in our method may be spread to carotenoids and other antioxidants, and thus broaden the application fields of biomolecules. Our preliminary investigations have shown that the facile, solution-phase biomolecule-assisted method can be potentially extended to the preparation of other low-dimensional nanostructures. The synthesized t-Se nanowires and nanoribbons may serve as templates to generate other tubular functional nanomaterials and find applications in the studies of structure–property relationships as well as in the fabrication of nanoscale optoelectronic devices.

A novel dynamic soft template solution route has been developed for the preparation of micrometre-sized In2S3 half-shells, assembled by fine nanoparticles. This novel half-shell nanostructure was characterized by electron microscopes, x-ray diffraction (XRD), x-ray photoelectron (XPS), and optical spectroscopes. The catalytic property in the electro-oxidation of the nitric oxide (NO) of the half-shells was also investigated, which could be drastically enhanced by the loading of Ag nanoparticles. Finally, the template-free, one-pot method described here is likely to be useful in the preparation of many other half-shell structures.

A solution-phase reaction under hydrothermal conditions at relatively low temperature is first put forward for the preparation of ?-AlOOH nanotubes and nanorods, on the basis of the possible strategy that the 2D framework structure of ?-AlOOH containing lamellae could provide orientation for the growth of 1D nanostructures. X-ray diffraction?(XRD) patterns, transmission electronic microscope?(TEM) images, Fourier transform infrared?(FTIR) spectra, and photoluminescence?(PL) spectra were used to characterize the products. A possible formation mechanism of nanotubes and nanorods from lamellar precursor is proposed.

P-type transparent CuAlO2 semiconductor films are made by the spin-on technique from nanocrystals. The nanocrystals are synthesized by a hydrothermal metathesis reaction. Scanning electron microscopy, x-ray diffraction and energy dispersive x-ray spectrometry suggest that the films contain nanocrystalline phases of CuAlO2. Both the Hall technique and Seebeck measurements reveal that the film is p-type and a very high room-temperature conductivity of 2.4S cm−1 is achieved. This success in fabricating a high-conductivity transparent CuAlO2 film indicates that nanotechnology will be helpful in enhancing the conductivity of p-type transparent semiconductors. The Hall measurement of the film shows a sheet mobility of 3.6 cm2 V−1 S−1 and a carrier concentration of 5.4 × 1018 cm−3. The optical band-gap of the film is estimated to be 3.75 eV and the activation energy for the positive hole is 0.14 eV.

The first-order metal-insulator transition (MIT) in magnetite has been known for a long time but is still controversial in its nature. In this study, well-defined magnetite nanocrystals (NCs) with controllable size, shape and terminated surface are first employed to elucidate this important issue, and new discoveries such as a highly suppressed phase transition temperature are identified by monitoring the variable-temperature electric resistance and infrared spectroscopy. Significantly, by carefully comparing the infrared vibrational bands of the as-prepared magnetite NCs with octahedral and cubic shapes, respectively, we found that these two forms of magnetite NCs exhibited different transmittance changes and frequency shifts of the infrared characteristics, presumably due to the differences in the lattice distortions on the corresponding {001} and {111} terminal surfaces. This result produced evidence in support of the charge ordering of Fe atoms along the low dimensionality at octahedral B sites undergoing the MIT. Taken together, infrared identification was proposed to be an available characterization strategy for MIT, which can reflect more information on the elusive lattice distortion of crystallographic structure or exposed surfaces.

Large-scale long continuous FeS(2) nanowire filled carbon nanotubes (CNTs) were one-step synthesized in the presence of NaN(3) in supercritical CS(2) at 500 °C using ferrocene as the iron source. The CNTs have outer diameters in the range of 15-25 nm and the core FeS(2) nanowires inside CNTs are characterized as single crystals, with an average diameter of 8 nm and up to several micrometres in length. The band gap of FeS(2) nanowire filled CNTs was determined as 5.69 eV from the ultraviolet and visible light absorption spectrum, showing its promise for application in reversible conversion between solar energy and electrical or chemical energy.

We report that the use of a chemically deposited ZnO energy barrier between a CdS quantum dot sensitizer and TiO(2) nanotubes (TNTs) can improve the efficiency of quantum dots-sensitized solar cells (QDSCs). The experimental results show that the formation of the ZnO layers over TNTs significantly improved the performances of the CdS QDSCs based on the TNTs electrodes. In particular, a maximum photoconversion efficiency of 4.6% was achieved for the CdS/ZnO/TNTs electrode under UV-visible light illumination, corresponding to an increase of 43.7% as compared to the CdS/TNTs electrode without the ZnO layers. The improved CdS QDSCs efficiency is attributed to the suppressed recombination of photoinjected electrons with redox ions from the electrolyte resulting from the ZnO energy barrier layers.

One-dimensional semiconductor ZnO nanostructures with different morphologies can provide different practical and potential applications in a broad field. In this paper, a one-dimensional zigzag chain coordination polymer [Zn(4,4(')-bipy)Cl(2)](n) and a two-dimensional coordination polymer [Formula: see text] are successfully promoted to obtain ZnO nanorods and radial nanoneedles on a large scale respectively, when they are directly employed as reactants. The different frameworks of coordination polymers can build various intermediates in the formation process, and the intermediates then mature to different morphologies in the final products. The possible formation mechanism and the PL spectra of both products are also investigated.

Porous cobalt nanowall arrays have been prepared by electrochemical deposition of mono-precursor [Co(NH(3))(5)Cl]Cl(2) on copper substrates. Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH) investigations of the surface properties indicate that the resulting porous nanomaterials possess high surface area and uniform pore size distribution, which implies potential applications in some fields, such as catalysis, energy, and magnetic data storage devices. The magnetism measurements of the porous cobalt nanowall arrays take on a good ferromagnetic behaviour with enhanced coercivity (H(c)).

A variety of inorganic nanomaterials have been shown to induce autophagy, a cellular degradation process critical for the maintenance of cellular homeostasis. The overwhelming majority of autophagic responses elicited by nanomaterials were detrimental to cell fate and contributed to increased cell death. A widely held view is that the inorganic nanoparticles, when encapsulated and trapped by autophagosomes, may compromise the normal autophagic process due to the inability of the cells to degrade these materials and thus they manifest a detrimental effect on the well-being of a cell. Here we show that, contrary to this notion, nano-sized paramontroseite VO2 nanocrystals (P-VO2) induced cyto-protective, rather than death-promoting, autophagy in cultured HeLa cells. P-VO2 also caused up-regulation of heme oxygenase-1 (HO-1), a cellular protein with a demonstrated role in protecting cells against death under stress situations. The autophagy inhibitor 3-methyladenine significantly inhibited HO-1 up-regulation and increased the rate of cell death in cells treated with P-VO2, while the HO-1 inhibitor protoporphyrin IX zinc (II) (ZnPP) enhanced the occurrence of cell death in the P-VO2-treated cells while having no effect on the autophagic response induced by P-VO2. On the other hand, Y2O3 nanocrystals, a control nanomaterial, induced death-promoting autophagy without affecting the level of expression of HO-1, and the pro-death effect of the autophagy induced by Y2O3. Our results represent the first report on a novel nanomaterial-induced cyto-protective autophagy, probably through up-regulation of HO-1, and may point to new possibilities for exploiting nanomaterial-induced autophagy for therapeutic applications.

We present the synthesis and visible-light-induced catalytic activity of Ag(2)S-coupled TiO(2) nanoparticles (NPs) and TiO(2) nanowires (NWs). Through a simple wet chemical process from a mixture of peroxo titanic acid (PTA) solution, thiourea and AgAc, a composite of Ag(2)S NPs and TiO(2) NPs with sizes of less than 7 nm was formed. When the NP composite was further treated with NaOH solution followed by annealing at ambient conditions, a new nanocomposite material comprising Ag(2)S NPs on TiO(2) NWs was created. Due to the coupling with such a low bandgap material as Ag(2)S, the TiO(2) nanocomposites could have a visible-light absorption capability much higher than that of pure TiO(2). As a result, the synthesized Ag(2)S/TiO(2) nanocomposites exhibited much higher catalytic efficiency for the decomposition of methyl orange than commercial TiO(2) (Degussa P25, Germany) under visible light.

Well-defined spherical CoS(2)@carbon core-shell nanoparticles, with an average diameter of 40 nm and thin graphite shell of 4 nm, were synthesized by the one-pot method in the presence of NaN(3) in supercritical CS(2) at 600 °C using cobaltocene as the cobalt source. The obtained product was characterized by XRD, Raman, FESEM, TEM and HRTEM and the possible formation mechanism was proposed here. Due to the good electronic conductivity and buffering matrix effect of graphitic carbon shells, the CoS(2)@carbon core-shell nanocomposite exhibited highly reversible capacity, good cycle performance and high Coulombic efficiency in lithium ion storage and retrieval, which makes it promising as an attractive anode material candidate for lithium ion batteries.

A facile biomolecule-assisted approach has been developed to prepare porous network-like metastable γ-MnS nanostructures through hydrothermal treatment of a homogeneous system of MnCl2 and L-cysteine. The morphology and phase of the MnS products can be controlled by adjusting the reaction temperature and molar ratio of the reagents (MnCl2 and L-cysteine). It was found that the γ-MnS porous networks formed via the aggregation and crystallization of the amorphous nanospheres. Preliminary UV–vis measurements have demonstrated that the as-prepared metastable γ-MnS networks exhibit original optical properties. These porous γ-MnS networks are expected to find potential applications in luminescence, optoelectronic and catalytic fields, as well as in the studies of structure–property relationships. This facile, environmentally benign and solution-phase biomolecule-assisted method can be potentially extended to the preparation of other magnetic chalcogenides including FeS, NiS and CoS nanostructures.