Junhan Kong

Controllable fabrication of nanostructured copper compound on a Cu substrate by a one-step route

We report a one-step corrosion process to synthesize nanostructured CuO thin films at room temperature. The reaction time has great effect on the composition and microstructure of products to control the size and shape of the copper compound. X-ray diffraction studies showed the transformation of nanograins from Cu(OH)2 nanowires to flower-like CuO and to dispersed CuO nanosheets. The optical properties of CuO nanosheets were investigated by using UV-vis spectroscopy with considerable blue-shift in the optical band gap (Eg = 1.8 eV) due to the quantum confinement effect. Additionally, the photocatalytic activities of as-prepared copper compound films were determined by measuring the degradation of methyl blue (MB) to find out their potential application in waste water treatment. The photoluminescence (PL) spectrum showed both UV as well as visible emission peaks, indicating their good optical properties. Moreover, a reasonable growth mechanism for the formation of the CuO nanostructure is proposed by means of a scanning electron microscope (FESEM).

Confined assembly of TiO 2 nanostructures in the nanochannels of AAO membrane

Nanochannels were attractive nanostructures due to their special small sizes and biomimetic functions. Here we reported a novel hybrid nanochannel, which combined with TiO2 nanostructures and anodic aluminum oxide (AAO) membrane. We used a facile solution-dipping method to make TiO2 nanostructures assemble in the nanochannnels of AAO membrane. The morphologies of nanochannels were monitored by field emission scanning electron microscopy and the micro-regional compositions were characterized by energy dispersive spectrometer. Optical information of the nanochannels were recorded by ultraviolet–Visible spectrophotometer, and the ionic current through nanochannels was recorded by an electrochemical workstation. From the results, the TiO2 nanostructures were well-anchored on the walls of nanochannels and the size of nanostructures was uniform. The optical properties and ionic current of hybrid nanochannels would change when the conditions of dipping method changed. For this, this nanochannel had huge potential in the field of photovoltaic conversion, ionic rectifier and biosensor.

Synthesis and Photocatalytic Properties of Ce-Doped TiO2 Nanotube Arrays via Anodic Oxidation

Ce-doped TiO2 nanotube arrays (TNAs) were prepared successfully through one-step anodic oxidation methods. The structural and morphological features of the TNAs were monitored by x-ray diffraction and field emission scanning electron microscopy with energy dispersive spectroscopy. Ultraviolet–visible light absorption spectra showed the light absorption performances of TiO2 nanotubes in both ultraviolet (UV) and visible light regions. Also, the photocatalytic activities of these samples were measured by the photodegradation rate of methylene blue (MB). The result indicated that doping a moderate amount of cerium ions into TNAs increased the absorption of both ultraviolet light and visible light obviously. However, the excess amount of doping ions would destroy the tubular structure severely and decrease the specific surface area of TNAs sharply. It could directly lead to the decreasing of photocatalytic activitity of TNAs. Furthermore, the best photodegradation rate of the Ce-doped TNAs on MB reached to 95.6%, which had a huge improvement comparing with pure TNAs.

Controllable synthesis, characterization of ZnS nanostructured spheres

ZnS nanostructured spheres have been synthesized successfully without the assisted of surfactant, templates or capping agent via a facile hydrothermal method. Structural, morphological and optical characterization was fully performed. On the basis of characterization results, it was founded that the concentration of sulfur sources, hydrothermal reaction time and reaction temperature had an important effect on the formation of ZnS nanostructured spheres. The reason that reaction parameters are how to affect the formation of nanostructured spheres was investigated and discussed in detail. The formation mechanism of nanostructured spheres was innovatively proposed based on experimental results. The strong green PL emission of such structures would provide a potential application in novel luminescent devices. In addition, the route for the synthesis of ZnS nanostructures will be a promising way in the industrial application.

Solution self-assembly of flower-like ZnO nanostructures with nanosheets and their optical properties

A uniform flower-like ZnO materials assembled by nanosheets have been synthesised on a large scale by a facile, cost efficient and room temperature solution route without the assistance of any substrate, template or seed layers. X-ray diffraction and field emission scanning electron microscopy were employed to characterise the phase composition and morphology of the samples, and ultraviolet–visible (UV-vis) diffuse reflectance spectrum and photoluminescence (PL) spectrum were used to analyse the optical properties of the samples. The flower-like ZnO materials with an average diameter of ∼2 μm are composed of interacted nanosheets with an average thickness of ∼5 nm. A reasonable growth mechanism that the formation of this kind of flower-like ZnO structures experienced a two-stage nucleation growth process was discussed. Based on the UV-vis diffuse reflectance spectrum, the band gap of hierarchical flower-like ZnO materials was calculated to be 3·27 eV. The PL spectrum suggests that flower-like ZnO materials only emit UV light and possess good optical properties.