Bimetallic nanostructures with magnetic and noble metals and their physicochemical applications

Bimetallic nanomaterials consisting of magnetic metals and noble metals have attracted much interest for their promising potentials in fields such as magnetic sensors, catalysts, optical detection and biomedical applications. Bimetallic nanomaterials synthesized by wet-chemical methods with different architectures including nanoparticles, nanowires or nanotubes and their assemblies are summarized in this review. The particular properties of bimetallic nanomaterials, especially their magnetic, catalytic and optical properties, are presented. The advance in electron microscopy makes it possible to understand the nanostructural materials at much higher level than before, which helps to disclose the relationship between the microstructures and properties qualitatively and quantitatively.     

Fabrication of Ni–Mo–Nb metallic glass/micro-nano lattice composite for nonenzymatic glucose sensing

The rising global diabetic population has ignited significant interest in enzyme-free electrochemical glucose sensors.However,their widespread usage has been severely impeded by the lack of sensing probes with both high sensitivity and stability.In this work,we present a novel approach for conformally depositing a Ni-Mo-Nb metallic-glass film onto a three-dimensional printed polymer skeleton for glucose detection.The printing template is designed based on a six-membered tricapped trigonal prism(...     

Gas sensors for CO_2 detection based on RGO–PEI films at room temperature

In this paper,polyethyleneimine(PEI)and reduced graphene oxide(RGO)were selected as sensing materials for carbon dioxide detection.Two kinds of sensors with different sensitive film structures,i.e.,RGO–PEI composite film and RGO–PEI bi-layer film were fabricated by airbrushing the sensitive films on interdigitated electrodes.Response performances of both sensors at room temperature were investigated.Results showed that sensors with bi-layer film exhibited smaller baseline drift and more stable sensing characteristics than the counterparts with composite film.Furthermore,bi-layer film sensors with different quantity of PEI solution deposited were studied.Performances of long-time stability,repeatability,low concentration of detection for carbon dioxide,and measurements of response time and recovery time were investigated.It was found that appropriate weight ratio of RGO and PEI was critical for sensing response.In addition,the sensor with bi-layer film exhibited a better repeatability but had longer response time and recovery time than RGO single-layer sensor,and both of them could detect as low as20 parts per million carbon dioxide gas.Sensing responses of the prepared sensors to carbon dioxide under dry air or nitrogen were compared.The relevant sensing mechanisms were studied as well.     

Preparation and characterization of oil-soluble In_2O_3 nanoparticles and In_2O_3–SnO_2 nanocomposites and their calcined thin films

Oil-soluble In2O3 nanoparticles and In2O3–SnO 2 nanocomposites were prepared in oleylamine via decomposition of metal acetylacetonate precursors. Thin films of In2O3 and In2O3–SnO 2 were obtained by spin-coating solutions of the oil-soluble In2O3 nanoparticles and In2O3–SnO 2 nanocomposites onto substrates and then calcining them. Transmission electron microspectroscopy, scanning electron microspectroscopy, atomic force microspectroscopy, X-ray diffraction, ultraviolet–visible absorption, and photoluminescence spectroscopy were used to investigate the properties of the nanoparticles and thin films. The In2O3 nanoparticles were cubic-phased spheres with a diameter of ~8 nm; their spectra exhibited a broad emission peak centered at 348 nm. The In2O3–SnO 2 nanocomposites were co-particles composed of smaller In2O3 particles and larger SnO 2 particles; their spectra exhibited a broad emission peak at 355 nm. After the In2O3–SnO 2 nanocomposites were calcined at 400°C, the obtained thin films were highly transparent and conductive, with a thickness of 30–40 nm; the surfaces of the thin films were smooth and crack-free.     

Optical nonlinearity and ultrafast dynamics of ion exchanged silver nanoparticles embedded in soda-lime silicate glass

Ag nanoparticles embedded in soda-lime silicate glass were fabricated by ion-exchange and subse-quently annealing method. Z-scan technique, femtosecond time-resolved optical Kerr effect （OKE） technique and femtosecond pump-probe experiment were used to investigate the effects of laser wavelength and laser pulse duration as well as annealing temperature on the third-order optical nonlinearity and ultrafast dynamics of the composites. It was found that the third-order susceptibility of Ag nanoparticles composite glass measured by 400 nm pulse source is larger than that measured by 800 nm pulse source due to an enhancement effect of local field near surface plasmon resonance of Ag nanoparticles in silicate glass. The third-order optical nonlinearity measured by ns laser source is about two orders of magnitude larger than that measured from fs pulse. The annealing temperature has an important effect on the third-order optical nonlinearity and ultrafast dynamics of the composites. Third-order nonlinear susceptibility up to 10^-l0 esu and fast relaxation process up to 0.2 ps have been obtained in Ag nanoparticles doped glass.     

Effect of homogenization process on the hardness of Zn–Al–Cu alloys

The effect of a homogenizing treatment on the hardness of as-cast Zn–Al–Cu alloys was investigated. Eight alloy compositions were prepared and homogenized at 350 ℃ for 180 h, and their Rockwell “B” hardness was subsequently measured. All the specimens were analyzed by X-ray diffraction and metallographically prepared for observation by optical microscopy and scanning electron microscopy. The results of the present work indicated that the hardness of both alloys (as-cast and homogenized) increased with increasing Al and Cu contents; this increased hardness is likely related to the presence of the θ and τ' phases. A regression equation was obtained to determine the hardness of the homogenized alloys as a function of their chemical composition and processing parameters, such as homogenization time and temperature, used in their preparation.     

Preparation of Pt–GO composites with high-number-density Pt nanoparticles dispersed uniformly on GO nanosheets

Pt–GO composites with high-number-density Pt nanoparticles dispersed uniformly on GO nanosheets were prepared using ethylene glycol as reducer at 180 °C. The nanoparticles had an average size of 12 nm with corners and edges on their surfaces. The composites had electrochemically active surface area of 31.7 m~2g~(-1) with a ratio(I_f/I_r =0.96) of the forward anodic peak current(I_f) to the reverse anodic peak current(I_r) in cyclic voltammetry curves, which is much higher than those of the reported Pt nanodendrites/reduced graphene oxide composites.     

High plastic Zr–Cu–Fe–Al–Nb bulk metallic glasses for biomedical applications

Four Zr–Cu–Fe–Al-based bulk metallic glasses(BMGs) with Zr contents greater than 65at% and minor additions of Nb were designed and prepared. The glass forming abilities, thermal stabilities, mechanical properties, and corrosion resistance properties of the prepared BMGs were investigated. These BMGs exhibit moderate glass forming abilities along with superior fracture and yield strengths compared to previously reported Zr–Cu–Fe–Al BMGs. Specifically, the addition of Nb into this quaternary system remarkably increases the plastic strain to 27.5%, which is related to the high Poisson's ratio and low Young's and shear moduli. The Nb-bearing BMGs also exhibit a lower corrosion current density by about one order of magnitude and a wider passive region than 316 L steel in phosphate buffer solution(PBS, pH 7.4). The combination of the optimized composition with high deformation ability, low Young's modulus, and excellent corrosion resistance properties indicates that this kind of BMG is promising for biomedical applications.     

Effect of nitrogen doping on structural and optical properties of ZnO nanoparticles

Infl uence of nitrogen doping on structural and optical properties of ZnO nanoparticles has been studied. Undoped and N doped ZnO nanoparticles were synthesized via chemical precipitation approach. The prepared samples were characterized through X-ray diffraction(XRD),Transmission electron microscopy(TEM) equipped with Energy dispersive X-ray(EDAX) spectroscopy, UV–visible spectroscopy, Fourier transform infrared(FTIR) spectroscopy and micro-Raman spectroscopy(m RS). Wurtzite phase of undoped as well as 0.5–10% N doped ZnO nanoparticles was con fi rmed through characteristic XRD patterns. The particle size expansion due to N incorporation in ZnO was further revealed by TEM and EDAX analysis where 11 nm size undoped and 18–22 nm size 0.5–10% N doped ZnO(N:ZnO) nanoparticles without any impurity were ascertained. Slight blue-shift in band gap energy, as observed in our case, symbolized weak quantum con fi nement of the prepared nanoparticles. The alterations in vibrational modes of ZnO due to N incorporation, remarkably H substituting at O site and subsequently causing the passivation in N:ZnO nanoparticles, were detected through FTIR analysis. Finally, the effect of the nano-size of crystallite and gradual prominence of N into ZnO lattice due to increase of N doping concentration in prepared nanoparticles was meticulously expatiated though m RS analysis.     

Glass and cellulose acetate fibers-supported boehmite nanosheets for bacteria adsorption

In this work, in situ method of producing hybrid fibrous adsorbents in which boehmite nanosheets with high sorption properties formed on the surface of hydrophilic microfibres, such as cellulose acetate and glass fibre,was described. The boehmite nanosheets were fabricated by the reaction of composite Al N/Al nanoparticles with water at 60 °C. The synthesized samples were characterized by X-ray diffractometer, scanning, transmission electron microscopy, Fourier transform infrared spectrometer(FT-IR), zeta-potential and specific surface area analyzers. The introduction of microfibres into a diluted aqueous suspension of nanopowders causes heteroadagulation of the nanoparticles and accelerates their further transformation. This effect is most substantial with the glass microfibre, which is thought to have a higher concentration of surface groups capable of generating hydrogen bonds that act as heteroadagulation and nucleation centres. The experimental results showed that the morphology of the resultant hybrid fibrous adsorbents differed accordingly: the nanosheets were attached on-edge to the glass microfibre surface, while on the surface of the cellulose acetate microfibre,they were secured in the form of spherical "nanoflowers" of agglomerated nanosheets. The effect of the morphology of hybrid fibrous adsorbents on adsorption bacteria Escherichia coli was also investigated.     

Laser-induced self-organization in Se–Te–Sn–Cd glassy semiconductor for developing novel light-sensing dielectrics

The laser-induced effects on dielectric properties of chalcogenide glass(Ch Gs) have been present in a glassy system of Se–Te–Sn–Cd for possible applications in optics and optoelectronics such as light-controlled capacitance-based touch displays. The temperature/frequency dependence of dielectric relaxation before and after laser exposure was investigated by using laser sources of different wavelengths(405 nm, 532 nm, 690 nm, and 785 nm). The result showed the presence of laser-induced residual effects on dielectric properties(dielectric constant/loss and a.c. conductivity) after the exposure of continuous-wave laser sources of chosen wavelengths.Further analysis indicates that the modification in the meta-stable state due to self-organization is the feasible mechanism of observed persistent light-sensing effects.     

Multiple metallic dopants in nickel nanoparticles for electrocatalytic oxygen evolution

Developing efficient oxygen evolution reaction(OER) electrocatalysts is of great importance for sustainable energy conversion and storage. Ni-based catalysts have shown great potential as OER electrocatalysts, but their performance still needs to be improved. Herein, we report the multiple metal doped nickel nanoparticles synthesized via a simple oil phase strategy as efficient OER catalysts. The FeMnMoV–Ni exhibits superior OER performance with an overpotential of 220 mV at 10 mA cm^-2     

Enhanced ductility of Mg–3Al–1Zn alloy reinforced with short length multiwalled carbon nanotubes using a powder metallurgy method

Mg–3Al–1Zn–CNTs composites, with different weight fractions(0.25–1.0 wt%) of carbon nanotubes(CNTs) were successfully fabricated via a powder metallurgy method. The processing parameters were adopted in such a way to have uniform dispersion of short length CNTs without any damage, as well as re fi ned and dissolved β phases structures throughout the composite matrix. The composite exhibited impressive increase in microhardness(about+23%) and tensile failure strain value(about+98%) without signi fi cant compromise in tensile strength, compared to the un-reinforced Mg–3Al–1Zn alloy. The synthesized composites can be used in automotive and aerospace industries due to their low density and high speci fic strength.     

Tailores Design and Characterization of Peroxide-containing Linear, Blick and Highly Branched Oligoelectrolytes and Derived Functional Nanoparticles with Special Properties

1 Results The development of novel surface-active block, comb-like and branched copolymers with peroxide-containing chains as well as derived functional luminescent and magnetic nanoparticles are the objectives of presented study. Main experimental approaches based on tailored synthesis of the oligoperoxide surfactants of desired structures and derived coordinating complexes of transitional and rare earth elements are developed. Functional oligoperoxide based possibilities of the synthesis of luminescent, magnetic and other functional nanocomposites with controlled size distribution, functionality, reactivity and biocompatibility are presented. Developed methods provide combining the stage of formation of polymeric, metal and metal-oxide nanoparticles with the stage of their surface irreversible modification by functional fragments capable of radical and other reactions including binding physiologically active substances. Novel nanoparticles are studied by chemical, colloidal-chemical, and rheological methods, X-ray diffraction technique, luminescent spectroscopy, transmission and scanning electronic microscopy. The availability of ditertiary peroxide fragments on nanoparticle surface causes their ability to radical grafting functional polymer chains. Functional nanoparticles developed are studied in phagocytosis, as markers of pathological cells, antimicrobial remedies and nanocarriers for targeted drug delivery.     

Effect of the CaO/SiO_2 mass ratio and FeO content on the viscosity of CaO–SiO_2–“FeO”–12wt%ZnO–3wt%Al_2O_3 slags

An effective process for recycling lead from hazardous waste cathode ray tubes(CRTs) funnel glass through traditional lead smelting has been presented previously. The viscous behavior of the molten high lead slag, which is affected by the addition of funnel glass, plays a critical role in determining the production efficiency. Therefore, the viscosities of the CaO–SiO_2–"FeO"–12wt%ZnO–3wt%Al_2O_3 slags were measured in the current study using the rotating spindle method. The slag viscosity decreases as the CaO/SiO_2 mass ratio is increased from 0.8 to 1.2 and also as the FeO content is increased from 8wt% to 20wt%. The breaking temperature of the slag is lowered substantially by the addition of FeO, whereas the influence of the CaO/SiO_2 mass ratio on the breaking temperature is complex. The structural analysis of quenched slags using Fourier transform infrared(FTIR) spectroscopy and Raman spectroscopy reveals that the silicate network structure is depolymerized with increasing CaO/SiO_2 mass ratio or increasing FeO content. The [FeO_6]-octahedra in the slag melt increase as the CaO/SiO_2 mass ratio or the FeO content increases. This increase can further decrease the degree of polymerization(DOP) of the slag. Furthermore, the activation energy for viscous flow decreases both with increasing CaO/SiO_2 mass ratio and increasing FeO content.     

Near-infrared absorption imaging and processing technologies based on gold nanorods

Noble metal nanoparticles with localized surface plasmon resonance (LSPR) properties are widely used as optical sensors in biochemical detection and medical diagnosis. In this paper, we propose an effective determination method to measure the LSPR absorption intensity of gold nanorods (GNRs). A near-infrared (NIR) imaging system is established, and an NIR absorption image of the multiple samples of the colloidal GNRs is captured. Then, the LSPR absorption intensities of these samples are obtained by calculating the average grayscale of the target areas based on the NIR image processing technology. By using this method, the LSPR absorption intensities of the multiple samples are determined all at once, and their accuracy is as high as that obtained by using spectrophotometry. These results suggest that this method is an efficient multi-channel determination technique with high-throughput sensing applications.     

One-pot synthesis and optical properties of In-and Sn-doped ZnO nanoparticles

Colloidal indium-doped zinc oxide(IZO) and tin-doped zinc oxide(ZTO) nanoparticles were successfully prepared in organic solution,with metal acetylacetonate as the precursor and oleylamine as the solvent. The crystal and optical properties were characterized by X-ray diffraction,UV?visible spectrophotometry,and fluorescence spectroscopy,respectively; the surface and structure morphologies were observed by scanning electron microscopy and transmission electron microscopy. The XRD patterns of the IZO and ZTO nanoparticles all exhibited similar diffraction peaks consistent with the standard XRD pattern of Zn O,although the diffraction peaks of the IZO and ZTO nanoparticles were slightly shifted with increasing dopant concentration. With increasing dopant concentration,the fluorescent emission peaks of the IZO nanoparticles exhibited an obvious red shift because of the difference in atomic radii of indium and zinc,whereas those of the ZTO nanoparticles exhibited almost no shift because of the similarity in atomic radii of tin and zinc. Furthermore,the sizes of the IZO and ZTO nanoparticles distributed in the ranges 20–40 and 20–25 nm,respectively,which is attributed to the difference in ionic radii of indium and tin.     

Gd–La codoped TiO_2 nanoparticles as solar photocatalysts

Gd–La codoped Ti O2 nanoparticles with diameter of 10 nm were successfully synthesized via a sol–gel method. The photocatalytic activity of the Gd–La codoped Ti O2 nanoparticles evaluated by photodegrading methyl orange was significantly enhanced compared to that of undoped or Gd or La mono-doped Ti O2. Ti4+tmay substitute for La3+tand Gd3+tin the lattices of rare earth oxides to create abundant oxygen vacancies and surface defects for electron trapping and dye adsorption, accelerating the separation of photogenerated electron–hole pairs and methyl orange photodegradation. It is believed that the formation of an excitation energy level below the conduction band of Ti O2 from the binding of electrons and oxygen vacancies decreases the excitation energy of Gd–La codoped Ti O2, resulting in versatile solar photocatalysts. The results suggest that Gd–La codoped Ti O2 nanoparticles are promising for future solar photocatalysts.     

Activator-assisted electroless deposition of copper nanostructured films

This paper showed simple and effective synthesis of copper nanoparticles within controlled diameter using direct electroless deposition on glass substrates, following the sensitization and activation steps. Electroless-deposited metals, such as Cu, Co, Ni, and Ag, and their alloys had many advantages in micro- and nanotechnologies. The structural, morphological, and optical properties of copper deposits were characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), and UV-Vis spectroscopy. The structural data was further analyzed using the Rietveld refinement program. Structural studies reveal that the deposited copper prefers a (111) orientation. AFM studies suggest the deposited materials form compact, uniform, and nanocrystalline phases with a high tendency to self-organize. The data show that the particle size can be controlled by controlling the activator concentration. The absorption spectra of the as-deposited copper nanoparticles reveal that the plasmonic peak broadens and exhibits a blue shift with decreasing particle size.     

Programmed self-assembly of DNA origami nanoblocks into anisotropic higher-order nanopatterns

Anisotropic nanopatterns have potentials in constructing novel plasmonic structures which have various applications in such as super-resolution microscopy, medicine, and sensors. However, it remains challenging to build big anisotropic nanopatterns that are suitable for big noble metal nanoparticles. Herein, we report a simple and reliable strategy for constructing DNA origami-based big anisotropic nanopatterns with controlled size and shape, nanoscale resolution, and fully addressability. Two kinds of basic DNA origami nanoblocks-cross-shaped and rectangular DNA origami units were used. We have demonstrated that by encoding nanoblocks’ edges, anisotropic higher-order nanopatterns, such as dimer, trimer, tetramer and mini "windmill" like pentamer nanopatterns could be constructed. To show the potential use as template to direct the assembly of anisotropic nanoparticles arrays, a proof of concept work was conducted by anchoring streptavidin nanoparticles on the "windmill" template to form a chiral array. Significantly, these nanopatterns have the sizes of hundreds of nanometers, which are in principle also suitable for big noble metal nanoparticles arrays.