Leshu Yu

Synthesis of graphene nanosheet powder with layer number control via a soluble salt-assisted route

The principle features in this study lay on the synthesis of graphene nanosheet powders with layer number control from pristine graphite powder via a soluble salt-assisted route and on the high thermal stability and good dispersibility of our products in ethanol.

ZnO nanopowders and their excellent solar light/UV photocatalytic activity on degradation of dye in wastewater

Low-cost and scalable preparation, high photocatalytic activity, and convenient recycle of ZnO nanopowders (NPs) would determine their practical application in purifying wastewater. In this contribution, ZnO NPs were scalably synthesized via the simple reaction of Zn powder with H2O vapor in autoclave. The structural, morphological and optical properties of the samples were systematically characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectra, transmission electron microscopy, Micro-Raman, photoluminescence, and ultraviolet-visible spectroscopy. The as-prepared ZnO NPs are composed of nanoparticles with 100–150 nm in diameter, and have a small Brunauer-Emmett-Teller surface area of 6.85 m2/g. The formation of ZnO nanoparticles is relative to the peeling of H2 release. Furthermore, the product has big strain-stress leading to the red-shift in the band gap of product, and shows a strong green emission centered at 515 nm revealing enough atomic defects in ZnO NPs. As a comparison with P25, the obtained dust gray ZnO NPs have a strong absorbance in the region of 200–700 nm, suggesting the wide wave-band utilization in sunlight. Based on the traits above, the ZnO NPs show excellent photocatalytic activity on the degradation of rhodamine B (Rh-B) under solar light irradiation, close to that under UV irradiation. Importantly, the ZnO NPs could be well recycled in water due to the quick sedimentation in themselves in solution. The low-cost and scalable preparation, high photocatalytic activity, and convenient recycle of ZnO NPs endow themselves with promising application in purifying wastewater.

Influence of sucrose solution's pH on hydrothermally synthesized carbon microspheres

ABSTRACT Using the hydrothermal method, carbon microspheres (CMSs) were prepared in sucrose solutions of different pH values by adding different amounts of HCl and NaOH. The surface structure and properties of the CMSs were characterized by SEM coupled with XRD, and the CMS particle size was analyzed using Nano Measurer 1.2.5. The results show that pH affects the shape, surface smoothness, dispersion, and particle size uniformity of the CMSs. The CMSs are larger for pH 7. In addition, when NaCl was added to the neutral sucrose solution, the growth and particle size of the CMSs were obviously affected, but their morphology remained the same.

Synthesis of Carbon Nanotubes by Using a Series of Phenyl Derivatives as Precursors

GRAPHICAL ABSTRACT Abstract A series of phenyl derivatives were systematically investigated as carbon source to prepare carbon nanotubes. The phenyl derivatives with electron-donating groups are ideal carbon sources for the mass production of CNTs, in which phenol is optimal. In this study, a series of phenyl derivatives including toluene, phenol, aniline, benzene, benzaldehyde, nitrobenzene, chlorobenzene and benzoic acid, were systematically investigated as carbon source to tentatively prepare carbon nanotubes (CNTs). The results were revealed that the phenyl derivatives with electron-donating groups were inclined to be dehydrogenated over the surface of metallic catalyst nanoparticles at low temperature, and the yield of CNTs obtained is high; whereas those with electron-withdrawing groups were difficult to be dehydrogenated over catalyst, and the growth temperature of CNTs is high, accordingly the resulted yield of product is low or even of naught. As a comprehensive comparison with other phenyl derivatives, phenol is the most ideal carbon resource to produce CNTs due to its very low toxicity, convenient transportation and reservation and high yield of CNTs.