Nano

Core/shell microspheres with functional Mn-doped ZnS microspheres (ZnS:Mn) as core and with nanosilica particles as shell were prepared by a combination of sol–gel and self-templating techniques. The characteristic of this novel method was that the whole process required neither additional surfactant nor stabilizer, which exempted from removing the template and reduced reaction steps compared to the conventional process. The morphologies, structure and particle size distribution of the resulting ZnS:Mn/SiO₂ microspheres were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. Surface chemical composition and optical properties were determined with X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy, respectively. In addition, the effects of reaction conditions on the structure and morphologies were investigated. Experimental results indicated that the resulting ZnS:Mn/SiO₂ microspheres were perfectly spherical with distinct core/shell structures, and exhibited stronger fluorescence emission.

Atomic force microscopy (AFM) investigating the sample morphology is the process of direct interaction between tip and surface features. The geometry of probe tip is a determining factor in correcting AFM images distorted by tip size itself. A quantitative knowledge of the current tip shape is needed to improve the reliability of AFM images. The biaxially oriented polypropylene (BOPP) film was fabricated and used as tip characterizer to estimate the morphology of AFM Si tip based on the blind reconstruction algorithm. The surface of the BOPP film was covered by nanometer-scale-sized structures which ensure that the tip profile can be determined accurately. Without independent knowledge of the sample, the three-dimensional (3D) shape of Si probe tip was obtained with high aspect ratio. BOPP film is not only a simple, cheap material but also a soft one which can also avoid tip damage in scanning. It was demonstrated reliable and suitable for tip characterization.

The heterostructure EuSe/Ag nanoparticles (NPs) were prepared through one-step colloid chemical method. Blue fluorescent EuSe NPs were prepared by amine reducing method with oleylamine (OLA) as surface stabilizer. The colloid microemulsion was formed through the mixture of AgNO₃ aqueous solution and the EuSe n-Hexane solution. On the interface, Ag⁺ ions could be reduced to Ag NPs by OLA. Finally heterogeneous EuSe/Ag NPs were obtained. The structure and properties of EuSe NPs and EuSe/Ag NPs were characterized by photoluminescence (PL), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results showed that the luminescence resonance energy transfer (LRET) occurred on the interface of EuSe NPs and Ag NPs. Also it demonstrated that the linear enhanced LRET effect happened with increasing the concentration of Ag⁺. All these properties make our heterostructural EuSe/Ag NPs to have interesting potential applications for ions detection and biosensors.

In this paper, epigallocatechin gallate (EGCG) was used as a green reductant both for the fabrication of soluble reduced graphene oxide (rGO) and the synthesis of Au nanoparticles/rGO nanocomposite. Fourier transform infrared (FTIR) spectra confirmed the efficient removal of the oxygen-containing groups in graphene oxide (GO) through the reduction act of EGCG. Au nanoparticles (AuNPs) were anchored onto the rGO sheets by heating the mixed solution of rGO and chloroauric acid at 65°C using EGCG as reductant. Transmission electron microscopy (TEM), atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the resulting nanocomposite. Due to the chelating effect of polyhydroxy EGCG, AuNPs with diameters of ~20–50 nm were stably decorated onto both sides of the rGO sheets. Because this reduction method avoids the use of toxic reagents, AuNPs/rGO nanocomposite would be eco-friendly, and it might be useful not only for electronic devices but also for biocompatible materials in the future applications.

The application of graphyne for a single-electron transistor (SET) that is operating in the Coulomb blockade regime is investigated in the first principles framework. Density functional theory modeling for graphyne has been used and the device environment has been described by a continuum model. The interaction between graphyne and the SET environment is treated with self-consistent Poisson equations. The charging energy as a function of gate voltage thus calculated has been used to obtain the charge stability diagram for the present system. The effect of electrode separation and the position of the molecule with respect to the dielectric on the gate coupling have been studied further. As compared with the previously studied systems on this line, graphyne has been observed to provide the gate coupling that is nearly close to that of benzene and graphene, but significantly greater than fullerene-based systems.

Co doped mesoporous carbon composites (MC–Co) have been synthesized at different carbonization temperatures via evaporation-induced multicomponent co-assembly strategy. The nanostructures and chemical compositions of MC–Co composites were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM) and X-ray diffraction analysis (XRD), etc. Their electromagnetic and microwave absorption properties were investigated in the frequency ranging from 2 GHz to 18 GHz. By the measurement of electromagnetic parameters and theoretical simulation of reflection loss (RL), the results showed that the minimum RL value of the optimum composite MC–Co-800 reached up to -41.9 dB at 13.5 GHz with a thickness of only 1.80 mm, and the effective absorption bandwidth (< -10 dB) is 4.4 GHz (from 11.4 GHz to 15.8 GHz). This work demonstrated that the optimum carbonization temperature of the obtained composites is 800°C, which is critical to its electromagnetic properties. The excellent microwave absorption properties can be attributed to dielectric loss, Ohmic loss, and characteristic impedance matching. Therefore, the as-synthesized composites could be acted as a candidate of microwave absorber, especially for the light weight demand.

In this research, mechanics of concentric ellipsoidal fullerenes inside open carbon nanocones (CNCs) is investigated. To this end, using continuum approximation in conjunction with Lennard-Jones (LJ) potential function, quadruple-integral expressions associated with van der Waals (vdW) potential energy and interaction force are first derived. For determination of these expressions, it is assumed that the fullerene molecule enters the open CNC through the small end or wide end. Thereafter, an efficient approach based on the differential quadrature (DQ) method is proposed to numerically evaluate the obtained quadruple integrals. The proposed method takes advantage of computing multidimensional integrals efficiently with using appropriate number of grid points. By introducing DQ-based operational matrices of differentiation and integration, the quadruple-integral expressions are estimated over their domains. Moreover, new semianalytical expressions are introduced in terms of triple integrals to evaluate vdW interactions. The validity and accuracy of the introduced numerical method are proved by comparing the results obtained through this method with ones achieved via the semianalytical expressions. The ease of implementation and quick answer of the demonstrated numerical solution enable us to comprehensively examine the effects of different geometrical parameters such as small end radius wide end radius and vertex angle of nanocone on the distributions of vdW potential energy and interaction force. The results reveal that the ellipsoidal fullerene undergoes an asymmetrical motion along the axis of open CNC.

A novel core–shell hybrid nanostructure was constructed by employing gold nanorod (AuNR) combined with rhodamine B (RB) as a core and silica as a shell. The poly(sodium 4-styrenesulfonate) (PSS), a negatively charged polyelectrolyte, played the role of linker to electrostatically trap RB on AuNRs. Due to the fluorescence spectral overlap between RB and AuNRs at 560 nm, the red fluorescence and enhanced green fluorescence of the hybrid nanostructures were observed obviously, which is capable for dual-color labeling. To reduce toxic side effects of AuNRs, silica was coated on AuNRs as a shell to fabricate the novel core–shell hybrid nanostructure function as a dual-color labeling for cancer-cell imaging. The fabricated composite structures were characterized by transmission electron microscopy (TEM), absorption spectrum, fluorescence spectrum, zeta potential measurements and laser scanning confocal microscope (LSCM). The experiment results confirmed that the obtained hybrid nanostructures provided excellent photostability, biocompatibility and active surface for further biological functionalization. The novel composite structures may have great potential application in cell multicolor labeling and imaging instead of traditional fluorescent dyes.

A 1,3-bis[(3,3-dimethylindolin-2-ylidene)methyl]squaraine (ISQ) dye sensitized ZnO nanocomposites via two different preparation methods including hydrothermal and ultrasonic sensitization processes are discussed in this paper. The as-prepared composites were characterized by the X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), Raman spectroscopy, and transmission electron microscopy (TEM). Based on the XRD patterns and TEM images, the ISQ/ZnO nanocomposites still kept the characteristic peaks and the basic morphology of ZnO and ISQ dye. The photocatalytic activity of ISQ/ZnO nanocomposites was investigated by degrading methylene blue (MB) under visible-light illumination. Compared with the MB self-degradation rate, the photocatalytic activity of the ISQ/ZnO composites was enhanced remarkably. The ISQ/ZnO nanocomposites fabricated by ultrasonic sensitization method exhibited excellent photocatalytic degradation rate, approximately 20% higher than that of the hydrothermal sensitization one.

Graphene oxide (GO) has attracted much attention as a derivative of graphene. In addition, it appears to have many unique physicochemical properties and has been investigated widely in many areas. Herein, we prepare GOs using flake graphite (FG), expandable graphite (EG) and microcrystalline graphite (MG) as graphite precursors by the modified Hummers method. According to the X-ray diffraction (XRD), Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, we characterize the component, the functional group, the chemical state of the element and the structural disorder of the obtained GOs to reveal their oxidation degree. Besides, we evaluate the hydrophilicity of the obtained GOs with the water contact angle, and observe their microstructures by transmission electron microscopy (TEM). We find that the GO prepared with EG has a higher-degree oxidation and better hydrophilicity, and it will be exfoliated easily and forms a monolayer or quasi-monolayer structure. Finally, based on the structural characteristic of graphite precursor, we build the intercalation and oxidation model to illuminate the phenomenon.

The oleate capped NaYF₄:Yb/Er upconversion nanoparticles (OA-UCNPs) were firstly synthesized by the thermal decomposition method and subsequently converted to water-dispersible, ligand-free UCNPs (LF-UCNPs) via an easy acid treatment process. The interaction of LF-UCNPs with bovine serum albumin (BSA) was then investigated. The binding of LF-UCNPs with BSA was confirmed by the static quenching of intrinsic fluorescence of BSA upon addition of LF-UCNPs. The spectra of synchronous fluorescence and circular dichroism (CD) of BSA in the absence and presence of LF-UCNPs revealed that the presence of LF-UCNPs led to a slight conformational change of BSA, suggesting a minor nanotoxicity of LF-UCNPs toward BSA.

In this paper, homogenous gold nanoparticles (AuNPs) with a high density and a narrow size distribution were successfully fabricated on titanate nanowires (TNWs) scaffolds in the absence of organic capping agents. An ameliorated low-temperature hydrothermal method was used to prepare the TNWs scaffolds like bird's nest on the Ti substrate, and the nanowires diameter was about 30–80nm. Then, AuNPs were synthesized on the TNWs scaffolds with a deposition–precipitation urea (DPU) method. The TEM and XRD measurements indicated that well-crystallized face-centered cubic (fcc) AuNPs were homogeneously dispersed on TNWs, and AuNPs with average sizes of 2.7 nm and 4 nm were obtained, respectively for the theoretical gold loading 5 wt.% and 8 wt.%. Inspiringly, the 8%-AuNPs/TNWs catalyst could reduce 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) within 210 s, and exhibited better catalytic reduction performance than that of 5%-AuNPs/TNWs.

Multi-walled carbon nanotubes (MWCNTs) are grafted with hyperbranched polysiloxane (HBPSi) by an efficient hydrosilylation method. In this hydrosilylation process, hydroxylated MWCNTs (HO-MWCNTs) are first functionalized by triethoxyvinylsilane to introduce carbon–carbon double bonds (C=C) on the surface of MWCNTs. The C=C is then reacted with the monomer of methylbis(dimethylvinylsiloxy)silane in the presence of the platinum–carbon catalyst, thus HBPSi is ultimately grafted on the surface of MWCNTs. Fourier transform infrared spectrometry (FTIR), Transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) are employed to characterize the changes in MWCNTs surface morphology, chemistry and physical conditions at different processing stages. The content of HBPSi on the surface of MWCNTs was also measured by the thermogravimetric analysis (TGA). The results indicate that the HBPSi successfully grafted on the surface of MWCNTs, and the dispersion of MWCNTs in organic solvent is also improved after functionalization.

Ag nanoparticles (Ag NPs) embedded carbon nanofibers (CNFs) were prepared by a new route which included chemical reaction process, electrospinning and calcination technique. The morphology and structure of the composite nanofibers were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and X-ray diffraction. It indicated that Ag NPs were uniformly distributed in the CNFs. This effective synthesis method can be used to prepare other composite nanofibers with functionality. The Ag NPs/CNFs that served as supported catalysts were used in the styrene epoxidation by TBHP. The Ag NPs/CNFs catalyst showed its highly catalytic activity for the epoxidation of styrene (conversion: 40.6%, SO selectivity: 35.9%). This kind of composite nanofiber membrane was proved effectively catalytic activity and recycled easily in the styrene epoxidation.