Nano

The supported nano-Bi₂WO₆–TiO₂/nickel foam photocatalyst was synthesized via spraying method with silica sol as a binder. The as-prepared photocatalyst with large surface and thermal stability exhibited enhanced photocatalytic performance for degradation of Rhodamine B (RhB) solution in sunlight irradiation. The results showed that the RhB solution could be degraded to 71.6% within 60min, exhibiting that improved photocatalytic activity increased by 77.6%, compared with that of pure Bi₂WO₆–TiO₂ nanoparticles. Its high photocatalytic activity was due to the presence of nickel foam in the catalytic process, making the Bi₂WO₆–TiO₂ highly dispersed and increasing the contact area of the photocatalysts with the organic pollutants. At the same time, a possible photocatalytic mechanism for the enhanced photocatalytic performance was investigated.

Antimony-doped tin oxide (ATO) was deposited on the surface of halloysite nanotubes (HNTs) to obtain conductive composite ATO/HNTs by a hydrolysis precipitation process. Structure and morphology of the samples were systematically characterized by X-ray diffraction (XRD), thermogravimetry–differential scanning calorimetry (TG–DSC), transmission electron microscope (TEM), energy-dispersive spectrometer (EDS) and Fourier transform infrared (FTIR) spectroscopy. The results indicated that ATO nanoparticles were successfully coated as thin layers on the surface of halloysite and the particle size was ∼7.4nm when calcined at 700°C. The ATO/HNTs composites were obtained with a resistivity of ∼430Ω⋅cm under the optimum experimental parameters. ATO layers were proved to attach to the halloysite surface via the Sn–O–Si or Sn–O–Al bonds. A corresponding coating mechanism was depicted.

In this paper, the In(OH)₃/Co(OH)₂/rGO (ICG) nanohybrids have been synthesized via a simple reflux method. It was found that the nanostructures were actually composed of thin nanosheets or nanowires. The addition of indium in Co(OH)₂ on rGO results in increase in the specific area of nanohybrids (105.7m²g^-1). That enhanced the gas sensing responses to NO_x compared with Co(OH)₂/rGO significantly. The ICG nanohybrids with the mass ratio of 5:1 (ICG-5) exhibited excellent gas-sensing properties with low detection limit of 0.97ppm and high sensitivity of 75.32% to 97ppm NO_x at room temperature (RT). The gas sensor also showed excellent selectivity to NO_x when other common gases such as NH₃, CO, C₂H₂ and H₂ were present. The sensing mechanism could be attributed to the charge carrier concentration of Co(OH)₂ greatly increased by indium doping, which at last encourages the electron transfer during the interaction with gases.

Titanium dioxide nanoparticles (TiO₂NPs) embedded carbon nanofibers (CNFs) have been successfully prepared by electrospinning technique, solvothermal synthesis and high-temperature calcination processes. The as-obtained products were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-Vis diffuse reflectance spectra (DRS) and Fourier transform infrared (FTIR) spectra. The results of characterization revealed that solvothermal treatment and high-temperature calcination were beneficial to the synthesis of anatase TiO₂. Compared to the as-fabricated TiO₂ powder, TiO₂ NPs contained in the TiO₂/CNFs were successfully grown on the surface of CNFs without aggregation. The photocatalytic activities of the TiO₂/CNFs heterostructures were evaluated by the degradation of methyl orange (MO) under UV light irradiation for 14h. The TiO₂/CNFs exhibited higher photocatalytic activities than pure TiO₂ powder, which were attributed to the small size of TiO₂ NPs, electron transfer, high adsorption properties of CNFs and the formation of heterostructures between TiO₂ and CNFs. Moreover, in aqueous solution, the as-prepared TiO₂/CNFs could be easily recycled for the application of CNFs.

Fe₃O₄–graphene nanocomposites were prepared via a simple hydrothermal method. Ultrafine Fe₃O₄ nanoparticles were evenly anchored on graphene substrates. As anode material for Li-ion batteries (LIB), the nanocomposite showed high initial discharge and charge capacities of 1456mAhg^-1 and 739.9mAhg^-1 at high current density of 500mAg^-1. Additionally, the charge capacity was also retained at 698.3mAhg^-1 after 200 cycles, thereby indicating excellent cycling stability. The results suggested that the as-prepared Fe₃O₄–graphene nanocomposite is a promising candidate for practical application as a Li-ion battery anode material.

CeO_x/C supported PtCu thin film catalysts were prepared by ion beam sputtering (IBS) and subsequently annealed at 400°C under vacuum environment and electrochemically dealloyed. Scanning transmission electronic microscope (STEM) and atomic force microscope (AFM) characterizations show that the surface of post-processed catalyst presents nanoporous structure and has a high root mean square roughness (RMS = 13.9nm). Electrochemical measurements indicate that the post-processed PtCu–CeO_x/C catalyst shows higher catalytic activity towards hydrogen evolution reaction than pure Pt/C. While inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis displays that the platinum (Pt) loading of the post-processed PtCu–CeO_x/C is 0.1192mg/cm², decreasing by 20% compare to pure Pt/C (0.1490mg/cm²). X-ray photoelectron spectroscopy (XPS) analysis confirms that the surface of post-processed PtCu–CeO_x/C enrich Pt and analyzes the chemical valence of Pt element using depth profiling technology. It can be inferred that the enhancement in catalytic property is attributed to the combined action between geometric structure effect and electronic modification effect of Pt atoms from CeO_x support.

Zinc oxide (ZnO) nanorods (NRs) have been synthesized as a template to fabricate TiO₂ nanotubes (TiNTs) on hemispherical diamond film by liquid-phase deposition (LPD) method. The process concerning the formation of TiNTs was analyzed. Based on the results of XRD and Raman spectroscopy, it is demonstrated that TiNTs was successfully obtained after removing ZnO NRs by chemical etching at room temperature. The TiNTs on hemispherical diamond film show higher performance photocatalysis, examined by the degradation of the reactive yellow 15 (RY15) solution. The corresponding mechanism is discussed.

Single-crystal hematite (α-Fe₂O₃) nanorings with three different thicknesses were synthesized by a hydrothermal method. The results of X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) show that the nanorings are single-crystal and have relatively uniform outer diameters of 160nm, and heights of about 100nm. Magnetic measurements up to 920K have been performed on hydrothermally synthesized α-Fe₂O₃ nanorings and nanoparticles using a quantum design vibrating sample magnetometer. A high temperature phase transition of thermal stability (α-Fe₂O₃ to Fe₃O₄) occurs when magnetic measurement was performed under high vacuum (< 9.5 × 10^-5 Torr). The phase transition temperature is 670K for nanorings with thickness of ∼30nm, 718K for nanorings with thickness of ∼50nm, 678K for nanorings with thickness of ∼65nm, and 640K for ∼35nm nanoparticles. This data show better thermal stability of nanorings with the thickness of ∼50nm than the other two kinds of nanoring samples The Néel temperature (T_N) of α-Fe₂O₃ nanorings with the thickness of ∼50nm is determined to be 937.2K by magnetic measurement for the first time, about 22.8K below the bulk value. The small reduction of the T_N of the α-Fe₂O₃ nanorings is consistent with the finite-size scaling theory.

The synthesis of bimetallic nanostructures using galvanic replacement displays a versatile route toward efficient catalysts for fuel cell reactions. We show that electrolessly plated Ag nanotubes (NTs) are a unique template for the synthesis of double-walled Ag–Pt NTs. After replacement reaction, different dealloying protocols are applied to adjust the residual Ag content. The structures were thoroughly characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy, providing evidence of a hollow tube structure composed of Ag–Pt alloy. Experiments under harsh conditions reveal, that a significant amount of Ag remain in the NTs, which strongly affects the methanol oxidation performance. With optimized Ag–Pt ratio, the specific activity of Pt/C catalysts can be outperformed. From the obtained results, we emphasize that each effort using galvanic replacement should be accompanied by detailed compositional analysis.

The utilization of ultrasound offers a facile tool for the synthesis of Au/AgCl hybrid particles. We have obtained the architectures of Au nanoparticles on AgCl sub-micrometer cubes by simply ultrasonic irradiating their precursors in ethylene glycol (EG). The formation process of Au/AgCl hybrid particles in the reaction solution has been studied based on the optical absorption spectra and the scanning electron microscope (SEM) images of the particles obtained at different ultrasonic irradiation stages. The dynamic changes of Au/AgCl hybrid particles under electron beam irradiation have been investigated in both SEM and in situ liquid cell transmission electron microscope (TEM). Hollow Au/AgCl hybrid particle structures have been obtained under the electron beam irradiation in liquid, with the cuboid contour shape preserved.

Porous hollow SnO₂ nanospheres were prepared by means of enforced Sn²⁺ hydrolysis method under hydrochloric acid medium. These hollow nanospheres with an average diameter of 220nm had a very thin shell thickness of about 40nm and were surrounded by elongated octahedral-like nanoparticles with the apex oriented outside. The experimental conditions, such as HCl content, reaction temperature and time directly dominated the morphology, structure and crystallinity of the obtained samples. A pre-oxidation-nucleation-growth mechanism and inside-out Ostwald-ripening method was proposed on the basis of the previous research and time-dependent experiments. Electrochemical tests showed that the porous hollow SnO₂ nanospheres exhibited improved cycling performance for anode materials of lithium-ion batteries, which retained a high reversible capacity of 540.0mAhg^-1, and stable cyclic retention at 120th cycle.

The reflection properties of light wave propagation in one-dimensional quasi-periodic metallic photonic crystal (PC) are comprehensively analyzed by transfer matrix method. In this work, we form a Fibonacci sequence quasi-periodic PC composed of metal and dielectric. The results demonstrate that the reflection stop band is strongly dependent on the periodic structure, metal thickness and incident angle. For this structure, the reflection stop band ranges from the visible light region to near-infrared region. Compared with the periodic metallic PC, the reflection stop bandwidth of our structure is wider. When the metal thickness increases, the reflection stop band is significantly enlarged. Furthermore, the reflection stop bandwidth slowly gets narrow and shifts to short wavelength region with the increase of incidence angle. Considering TE and TM wave at all incident angles, there is an omnidirectional reflection bandgap with width of 241nm for our investigated quasi-periodic metal PC.

Carbon-coated nickel nanoparticles with a mean diameter of 40nm were synthesized via solid-phase pyrolysis of nickel-phthalocyanine. The composition structure and morphology of samples were investigated by scanning and transmission electron microscopy, X-ray diffraction, Raman spectroscopy and energy-dispersive X-ray microanalysis. Magnetic characteristics of samples were measured with a vibrational magnetometer and a magnetic resonance spectrometer. The main mass of Ni ferromagnetic nanoparticles have a single-domain and a vortex (pseudo-single domain) structures. We also revealed superparamagnetic Ni nanoparticles (several percent) and carbon paramagnetic centers caused by defects in the carbon matrix. We determined the main magnetic characteristics of Ni nanoparticles, their temperature and field dependences as well as the parameters of ferromagnetic resonance spectra.

Highly ordered mesoporous antimony-doped tin oxide (ATO) materials, containing different amount of antimony in the range of 0–50mol%, are prepared via a nanoreplication method using a mesoporous silica template. The mesoporous ATO materials thus obtained exhibit high electrical conductivity, high reversible capacity, superior cycle stability and good rate capability as anode materials for lithium-ion batteries, compared to those of pure mesoporous tin oxide. Amongst the ATO materials in this work, the mesoporous ATO material with 10mol% of antimony has highest discharge capacity of 1940mAhg^-1 (charge capacity of 1049) at the 1st cycle, best cycle performance (716mAhg^-1 at 100th cycle) and excellent rate capability, which are probably due to the enhanced electrical conductivity as well as reduced crystalline size.

Graphene, a single sp² bonded carbon, is now a burgeoning interest with various fascinating properties in a large number of biomedical applications. Consequently, the impact of graphene-based functional nanohybrid and its potential risk to human health have raised considerable public concerns. In this present study, we have synthesized cerium oxide (CeO₂) anchored reduced graphene oxide (RGO) nanohybrid and a detailed study on its nanotoxicity profile has also been scrutinized. To confirm the efficient synthesis of nano-CeO₂/RGO nanohybrid, the systematic characterization has been carried out using FTIR, Raman and UV-Vis spectroscopic analysis. The successful imprint of CeO₂ nanoparticles (NPs) on RGO nanosheet was also evident from the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs. A dose-dependent in vitro nanotoxicity of the nanohybrid has been assessed by using monocyte macrophage cells-Raw264.7 and colon cancer cells-HCT116 as compared with RGO and CeO₂. The results conferred that as compared with single nanostructures (RGO or CeO₂), nanohybrid showed excellent biocompatibility and no such prominence morphological alteration of the cell structure. Moreover, after exposure of different nanomaterials to HCT116 cells, the possible cellular interaction was investigated through reactive oxygen species (ROS) measurements using flow cytometry analysis dicholoro-dihydro-fluorescen dia-acetate (DCF) assay. These results conveyed that nanohybrid adapts an oxidative stress mechanism upon cellular interaction where it utilizes the scavenging property of CeO₂, which induces the cell proliferation. Overall, the nano-CeO₂/RGO nanohybrid exhibits a prolonged biocompatibility and cell viability, which is highly desired for biomedical applications.

In this study, a novel method, electrospinning, was used to prepare lignin-based carbon nanofibers. The major material was lignin. The chemical and thermal properties of different lignins were characterized to determine their suitability for partial incorporation of polyacrylonitrile (PAN). Then the precursor fibers were carbonized at a temperature from 600°C to 1000°C, respectively to prepare biomass-based carbon nanofibers. The influences of carbonization temperature on prepared carbon nanofibers were investigated by X-ray diffraction (XRD), Raman, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results indicated that the diameter of prepared precursor fibers and carbon fibers were about 200nm and 100nm, respectively. The increase of temperature has little influence on the carbon fiber graphitization degree. The D band of the carbon fibers carbonized at 900°C is lowest. The thermal stability of the carbon fibers changes little with rising temperature when carbonized temperature exceeds 900°C, and carbon fibers carbonized under 900°C have most compact structure. Therefore, the above conclusions make clearly that 900°C is the optimal carbonization temperature for preparing lignin-based carbon nanofibers in this technique. Meanwhile, the study is a doubled-edged enterprise that aims to recycle the waste from pulping industry as well as to turn it into a valuable material.