Yinjie Wang

Facile synthesis of monodispersed silver nanoparticles on graphene oxide sheets with enhanced antibacterial activity

Graphene oxide–Ag nanoparticle (GO–Ag) composites were synthesized through a facile two-phase (toluene–water) process. Transmission Electron Microscopy and X-ray diffraction analysis revealed that the Ag nanoparticles anchored on GO sheets were spherical in shape and highly monodispersed with uniform size of 6 nm. The antibacterial activity of GO–Ag composites was investigated against gram-negative bacteria Escherichia coli (E. coli) and showed a remarkably enhanced antibacterial activity compared with the original Ag nanoparticles, suggesting that the as-prepared nanocomposites may be used as effective antibacterial materials.

High-quality reduced graphene oxide-nanocrystalline platinum hybrid materials prepared by simultaneous co-reduction of graphene oxide and chloroplatinic acid.

Reduced graphene oxide-nanocrystalline platinum (RGO-Pt) hybrid materials were synthesized by simultaneous co-reduction of graphene oxide (GO) and chloroplatinic acid with sodium citrate in water at 80°C, of pH 7 and 10. The resultant RGO-Pt hybrid materials were characterized using transmission electron microscopy (TEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy, and thermogravimetric analysis. Platinum (Pt) nanoparticles were anchored randomly onto the reduced GO (RGO) sheets with average mean diameters of 1.76 (pH 7) and 1.93 nm (pH 10). The significant Pt diffraction peaks and the decreased intensity of (002) peak in the XRD patterns of RGO-Pt hybrid materials confirmed that the Pt nanoparticles were anchored onto the RGO sheets and intercalated into the stacked RGO layers at these two pH values. The Pt loadings for the hybrid materials were determined as 36.83 (pH 7) and 49.18% (pH 10) by mass using XPS analysis. With the assistance of oleylamine, the resultant RGO-Pt hybrid materials were soluble in the nonpolar organic solvents, and the dispersion could remain stable for several months.

Surface Morphology Evolution of GaAs by Low Energy Ion Sputtering

Low energy Ar+ion sputtering, typically below 1,200 eV, of GaAs at normal beam incident angle is investigated. Surface morphology development with respect to varying energy is analyzed and discussed. Dot-like patterns in the nanometer scale are obtained above 600 eV. As the energy approaches upper eV range regular dots have evolved. The energy dependent dot evolution is evaluated based on solutions of the isotropic Kuramoto-Sivashinsky equation. The results are in agreement with the theoretical model which describes a power law dependency of the characteristic wavelength on ion energy in the ion-induced diffusion regime.

Simultaneous copper ion removal and hydrogen production from water over a TiO2 nanotube photocatalyst.

A one-dimensional (1-D) mesoporous TiO₂ nanotube (TiNT) was successfully synthesized via a hydrothermal-calcination process, and employed in simultaneous photocatalytic Cu(2+) removal and H₂ production. Under irradiation, Cu(2+) in the wide concentration range of 8-800 ppm, could be reduced rapidly, and the reduction was not severely impacted by co-existing inorganic ions in solution. Simultaneous with Cu(2+) reduction, noticeable H₂ was produced over the in-situ fabricated Cu incorporated TiNT (Cu-TiNT) photocatalyst, while H₂ evolution rate was controlled by the Cu(2+) reduction process, due to competition of electron capture between protons and Cu(2+). In addition, H₂ generation activity of Cu-TiNT depended on the initial Cu(2+)/Ti ratio, and could be depressed by co-existing ions in solution. Fast Cu(2+) reduction and remarkable H₂ evolution confirmed the feasibility of simultaneous Cu(2+) removal and H₂ production over a TiNT photocatalyst.