Nano

Core/shell type carbon-coated Fe nanocapsules (Fe@C NCs) were in situ synthesized by DC arc-discharge plasma method in methane atmosphere. Such Fe nanocapsules have saturation magnetization of 29.32emu/g and specific surface area of 85.86m²/g. The carbon shell of Fe@C NCs was functionalized with oxygen-containing groups (such as –OH or –COOH) by using H₂O₂. The adsorption of organic dye, e.g., methylene blue (MB) was systematically investigated in different conditions, such as contact time, pH values and temperature. The maximum adsorption capacity (46.5mg/g) was calculated by fitting the adsorption isotherms with Langmuir model, coincident with the experimental result of 44.5mg/g. Kinetics data supported pseudo-second order model, and the thermodynamic process of adsorption was revealed as endothermic and spontaneous physisorption. The MB-absorbed Fe@C NCs can be entirely separated from the contaminative solution by a magnetic field and then successfully cycled for regeneration. After repetitive cycles of the adsorption/desorption experiments for five times, the removal efficiency can be maintained over 90%.

Al/Fe/Co doped ordered mesoporous carbon (OMC) composites have been synthesized by a facile method, and the influence of dopant on the electromagnetic (EM) and microwave absorption properties was investigated in the frequency range of 2–18GHz. Compared with Fe/Co–OMC composites, the Al–OMC nanocomposite played a great role in adjusting values and frequency dependence of complex permittivity, which gives rise to significant improved microwave absorption and reduced thickness of the corresponding paraffin wax composites. Reflection loss (RL) values less than $-$5dB and $-$10dB were obtained in the frequency range of 9.2–18GHz and 10.7–14.7GHz with a single thickness of 2.00mm, respectively. Such enhanced EM wave absorption property of the Al–OMC/paraffin wax composite was ascribed to its superior impedance matching characteristic. Thin thickness, broadband absorption microwave absorbers with Al doped OMC nanocomposites were obtained.

The composite supercapacitor electrodes were rationally fabricated by facile electrochemical deposition of polypyrrole (PPy) on NiCo₂O₄ nanowire arrays which were grown radially on carbon fiber (CF). When used as electrodes in supercapacitors, the composite nanostructures demonstrated prominent electrochemical performances with a high areal capacitance (1.44F/cm² at a current density of 2mA/cm²), a good rate capability (80.5% when the current density increases from 2mA/cm² to 20mA/cm²), and a good cycling ability (85% of the initial specific capacitance remained after 5000 cycles at a high current density of 10mA/cm²). The excellent electrochemical performance of NiCo₂O₄@PPy nanostructures can be mainly ascribed to the good electrical conductivity of PPy, the enhanced adherent force between electrode materials and CF to hold the electrode fragments together by means of NiCo₂O₄ nanowires, the short ion diffusion pathway in ordered porous NiCo₂O₄ nanowires and the three-dimensional nanostructures.

Aluminum nitride (AlN) with strong blue emission at 450nm has been synthesized from hexahydrate aluminum chloride and urea above $850^{\circ }$C via a solventless route. Several aluminum and nitrogen sources are selected and well investigated to determine the effect of AlN synthesis. Moreover, the structure, component, morphology, photoluminescence properties and possible synthesis mechanism are also discussed carefully.

The electron field emission (EFE) properties of vertically aligned arrays of silicon nanowires (SiNWs) grown from silicon substrate at different gold sputtering periods of 0s, 8s, 15s and 25s at a rate of 10nm/min by electroless metal deposition process were investigated. It has been observed that the transformation of silicon tips from irregular to highly dense and uniform cylindrical morphological nanostructures with an increase in Au sputtering periods. A significant enhancement in EFE properties of as-prepared arrays of SiNWs with the increase in Au sputtering periods is observed. The threshold fields for attaining current density of 0.1mA${\mathrm{\text{cm}}}^{-2}$ were decreased gradually as 32.38$\mathrm{\text{V}}\mu {\mathrm{\text{m}}}^{-1}$, 29.37$\mathrm{\text{V}}\mu {\mathrm{\text{m}}}^{-1}$ and 23.19$\mathrm{\text{V}}\mu {\mathrm{\text{m}}}^{-1}$ for the arrays of SiNWs synthesized from Si substrate by Au coating of 8s, 15s and 25s respectively. Moreover, from Fowler–Nordheim plot, the turn-on field is observed to decrease from 16.56$\mathrm{\text{V}}∕\mu \mathrm{\text{m}}$ for as-prepared to 8.77$\mathrm{\text{V}}∕\mu \mathrm{\text{m}}$ for 25s Au sputtered SiNW arrays. The effective work functions of the electron emitting array of SiNWs have been improved from 0.5meV to 0.1meV.

Nanoscaled CeO₂/e-HTiNbO₅ composite was assembled by a facile process using colloidal TiNbO${}_5^{-}$ (e-HTiNbO₅) nanosheet and CeO₂ colloid as precursors at room temperature. The nanosheet e-HTiNbO₅ was obtained through proton-exchange and exfoliation process from its parent KTiNbO₅. The microstructures and properties of the as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Laser Raman spectroscopy (LRS), and UV-vis diffuse reflectance spectroscopy (UV-vis DRS), etc. The photocatalytic activity of the obtained nanocomposite is evaluated by the adsorption and photocatalytic oxidation of ethyl mercaptan (EM) under natural light irradiation. The results show that CeO₂ nanoparticles are dispersed uniformly on the surface of e-HTiNbO₅ and the layered structure of e-HTiNbO₅ nanosheet maintains integrity. The interaction between dispersed CeO₂ particles and e-HTiNbO₅ results in lower bandgap compared to its precursors, and the photocatalytic activity of CeO₂/e-HTiNbO₅ are enhanced under natural light irradiation.

ZnO:Al/p-Si heterojunction was fabricated by depositing a hexagonal nanocrystal ZnO:Al film on p-type Si substrate using a simple chemical bath deposition (CBD) method. The vertically aligned hexagonal ZnO:Al nanocrystals reduce the grain boundary scattering and provide good conductivity. The ZnO:Al/Si heterojunction shows obvious photocurrent under ultraviolet (UV) illumination. A high UV-to-visible rejection ratio of the ZnO:Al/Si heterojunction indicates that the hexagonal nanocrystal ZnO:Al film is a good material for fabricating UV photodetectors. Furthermore, the response speed of the photodetector based on ZnO:Al hexagonal nanocrystal film is faster than that of most previously reported photodetectors based on ZnO:Al nanorods. We infer it is because the ZnO:Al nanocrystals film has a smaller surface to volume ratio than the ZnO:Al nanorod array.

In this work, graphene oxide/polyaniline (GO/PANI) nanocomposites were synthesized by an in situ polymerization of aniline monomer in GO aqueous dispersions. The morphology and structure of GO/PANI were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra and Raman spectra. The effects of the concentration of GO/PANI and temperature on the rheological behavior of silicone oil dispersions of GO/PANI nanocomposites were investigated. The results showed that the steady state viscosity of GO/PANI dispersions remarkably increased with the addition of only little GO and the concentrated dispersions showed characteristic shear-thinning behavior. Significantly, a Newtonian-pseudoplastic transition with a critical exponent of 2.2 was observed in silicone oil dispersions of GO/PANI with the increase of nanocomposites concentration. The viscosity of GO/PANI dispersions apparently decreased with increasing temperature, while the temperature showed a certain effect on the thixotropic behavior of concentrated dispersions. In addition, the effect of the GO content on the electrical conductivity of GO/PANI nanocomposites was also explored. It was noted that the GO sheets are effective fillers for improving the rheological behavior and electrical conductivity of PANI matrix. Therefore, the study of rheological behavior and electric property of GO/PANI nanocomposites could shed light on the processing and application of GO/conductive polymer nanocomposites.

Colloidal CdSe nanocrystals (NCs) were etched after Se/TBP and Zinc stearate/ODE were injected into the mixture of as-prepared CdSe NCs and Copper (II) acetate in ODE solvent. Spectroscopic and structural investigations demonstrate the etching process. Along with the etching time, both the absorption and photoluminescence (PL) spectra of etched NCs showed blue-shift while the transmission electron microscopy (TEM) images indicated that the size of the NCs became from 5.6nm to 2.6nm. X-ray diffraction (XRD) patterns suggested that no other clusters or core/shell NCs were formed in the etching process and inductively coupled plasma (ICP) data demonstrated that only selenium and cadmium comprised the etched NCs. Electronic paramagnetic resonance (EPR) spectra indicated the deoxidization of Cu${}^{2+}$ ions and suggested the etching mechanism through cation exchange process.

PtRu nanoparticles (NPs) supported on acid treated multiwall carbon nanotubes (Pt₁Ru₁/MWCNTs) were prepared by a modified polyol method without adding any other surfactant or protective agent. The structural and compositional properties of the as-obtained samples were characterized by transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and X-ray photoelectron (XPS) spectroscopy. The electrocatalytic performance of the catalyst was evaluated by cyclic voltammetry (CV), CO stripping voltammetry and chronoamperometry, indicating a high catalytic activity, excellent CO tolerance and stability for methanol oxidation. Interestingly, a series of accurate controllable experiments have been designed to explore the enhancement mechanism of Pt₁Ru₁/MWCNTs for methanol oxidation reaction. Most importantly, Pt₁Ru₁/MWCNTs composites were used as an anode catalyst in the direct methanol fuel cells (DMFCs) exhibiting outstanding power density (126.1 mW/cm${}^{\mathrm{\text{2}}})$ 1.7 times higher than that of the commercial catalyst of Pt₁Ru₁/C (74.1 mW/cm${}^{\mathrm{\text{2}}})$ (E-TEK).

We introduce a two-step hydrothermal and microwave method to prepare novel SnO₂/MoS₂ composites. The as-prepared samples are well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The experimental results indicate that the SnO₂/MoS₂ composites are composed of MoS₂ nanosheets and ultrafine SnO₂ nanoparticles with mean size of 3–4nm which are well-distributed and anchored on the surface of MoS₂ nanosheets. The resultant composites demonstrate prominently improved electrochemical performances, which could be attributed to the unique and robust microstructures and synergetic effect between MoS₂ and SnO₂.

Ordered ZnO arrays with a peculiar nanostructure were synthesized by a multistep synthesis process. The first step was the preparation of ZnO seed to induce the formation of ZnO array via potentiostatic electrodeposition method using a typical three electrode set-up. The second step was fabricating ZnO array along seed by Chemical Bath Deposition. Structural analysis of ZnO was carried out with X-ray diffraction (XRD), which showed a hexagonal wurtzite structure, and the selected area electron diffraction (SAED) patterns indicated that nanocrystalline is a part of monocrystal. The scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to study the microstructure, and showed a pagoda-like microstructure with a tiny top and large bottom, which had an average top diameter of exceeding 800nm at seed-depositing time of 60s, and then growth mechanisms are subsequently given a further explanation, viewed from kinetics and thermodynamics. In addition, the current–voltage curves of schottky diode devices with ZnO nanopagoda arrays revealed that ZnO films arrays along grown ZnO seed had a higher reverse saturation current than ZnO films grown without seed, which are $1.48\times 10^{-6}$ A and $1.32\times 10^{-8}$ A, respectively. The minimum turn-on voltage of the diode with ZnO seed deposited 60s is 0.18V, without seed is 0.52V.