Yina Guo

Colloidal synthesis of Cu2SnSe3 tetrapod nanocrystals.

The formation of Cu2SnSe3 tetrapod nanocrystals is reported using a hot injection colloidal synthesis. The ternary copper chalcogenide nanocrystals nucleate with a cubic core with four short wurzite arms.

Factors Influencing the Performance of Pd/C Catalysts in the Green Production of Hydrogen from Formic Acid.

Formic acid derived from biomass is known to be used for hydrogen production over Pd catalysts. The effects of preparation variables, structure of the carbon support, surface functional composition on the state of Pd, and catalytic properties of the samples in the vapor-phase decomposition of formic acid were studied. In all catalysts derived from Pd acetate, metal particles visible by conventional TEM had similar sizes, but the adsorption capacity towards CO responded strongly to N-doping of the carbon surface. Moreover, a decrease in the CO/Pd values was accompanied by a significant increase in the reaction rate. Taking account of X-ray photoelectron spectroscopy (XPS) and atomic resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF/STEM) data, the trends observed were assigned to a larger fraction of single electron-deficient Pd atoms in the N-doped samples, which do not adsorb CO but interact with formic acid to produce hydrogen. This was confirmed by extended DFT studies. The obtained results are valuable for the development of Pd catalysts on carbon supports for different processes.

Effects of Polydopamine Functionalization on Boron Nitride Nanotube Dispersion and Cytocompatibility

Boron nitride nanotubes (BNNTs) have unique physical properties, of value in biomedical applications; however, their dispersion and functionalization represent a critical challenge in their successful employment as biomaterials. In the present study, we report a process for the efficient disentanglement of BNNTs via a dual surfactant/polydopamine (PD) process. High-resolution transmission electron microscopy (HR-TEM) indicated that individual BNNTs become coated with a uniform PD nanocoating, which significantly enhanced dispersion of BNNTs in aqueous solutions. Furthermore, the cytocompatibility of PD-coated BNNTs was assessed in vitro with cultured human osteoblasts (HOBs) at concentrations of 1, 10, and 30 μg/mL and over three time-points (24, 48, and 72 h). In this study it was demonstrated that PD-functionalized BNNTs become individually localized within the cytoplasm by endosomal escape and that concentrations of up to 30 μg/mL of PD-BNNTs were cytocompatible in HOBs cells following 72 h of exposure.

High density and patternable growth of silicon, germanium and alloyed SiGe nanowires by a rapid anneal protocol

We report the formation of silicon, germanium and alloyed Si1−xGex nanowires by direct pyrolysis of liquid precursors on a heated substrate in an inert environment. The nanowires form in high density on the substrate with a fast reaction time. We use SEM, HRTEM, EDX-STEM, and Raman spectroscopy to carry out an in depth study into the population distribution of Si1−xGex nanowires. The method was sufficiently adaptable to pattern the nanowire growth using standard dry film lithography techniques. Additionally, we further show that direct writing with a copper metal pen deposited sufficient catalyst to allow localised nanowire growth constrained to the treated areas.

The selective synthesis of nickel germanide nanowires and nickel germanide seeded germanium nanowires within a solvent vapour growth system

We report the formation of NiGe nanowires by the thermal decomposition of diphenylgermane, in the presence of a bulk Ni foil, in a solvent vapor growth system. The reaction occurs by the initial formation of a NiGe layer on the foil which progresses to the growth of nanowire occlusions of the same phase, typically 40 nm in diameter. Switching the substrate from bulk Ni foil to an evaporated layer of Ni results in the growth of NiGe seeded germanium nanowires, in high yield. The nanowires were characterized using high resolution scanning electron microscopy, X-ray diffraction, and high resolution transmission electron microscopy.

Assembling Ordered Nanorod Superstructures and Their Application as Microcavity Lasers

Herein we report the formation of multi-layered arrays of vertically aligned and close packed semiconductor nanorods in perfect registry at a substrate using electric field assisted assembly. The collective properties of these CdSexS1-x nanorod emitters are harnessed by demonstrating a relatively low amplified spontaneous emission (ASE) threshold and a high net optical gain at medium pump intensity. The importance of order in the system is highlighted where a lower ASE threshold is observed compared to disordered samples.

Recyclable SERS substrates based on Fe2O3–Ag hybrid hollow microspheres with crumpled surfaces

Fe2O3–Ag hollow microspheres (FAHMs) with crumpled surfaces were prepared by solvothermal treatment with post-calcination. The as-prepared hybrid microspheres were first used as an active substrate for surface-enhanced Raman scattering (SERS) of a small molecule, 4-aminobenzenethiol (4-ABT), and an enhancement factor of 9.6 × 104 was achieved. In addition, the FAHMs provided photocatalytic activity to the absorbed 4-ABT after exposure to visible light for 5 min and can be recycled five times without a decrease in the SERS performance. Furthermore, the prepared FAHMs are also a possible substrate for macromolecule ricin and the recyclability can be achieved by water activation.