Role of ZnO-CeO_2 Nanostructures as a Photo-catalyst and Chemi-sensor

ZnO-CeO2 nanostructures were synthesized by simple and effcient low temperature method. The structure and morphology of the ZnO-CeO2 nanostructures were characterized by X-ray powder diffraction （XRD） and field emission scanning electron microscopy （FESEM）, which revealed elongated shaped CeO2 nanoparticles with diameters of 40–90 nm distributed on the surface of elongated ZnO nanostructures with diameters of 50–200 nm （edge–centre）. Further the structure of the synthesized ZnO-CeO2 nanostructure was supported by Raman spectra and Fourier transform infrared spectroscopy （FTIR）. UV-vis absorption spectrum was used to confirm the optical properties of the CeO2 doped ZnO nanostructures. Photo-catalytic activity of CeO2 doped ZnO nanostructure was evaluated by degradation of acridine orange and methylene blue which degraded 84.55% and 48.65% in 170 min, respectively. ZnO-CeO2 nanostructures also showed good sensitivity （0.8331 μA·cm-2·（mol/l）-1） in short response time （10 s） by applying to chemical sensing using ethanol as a target compound by I-V technique. These degradation and chemical sensing properties of ZnO-CeO2 nanostructures are of great importance for the application of ZnO-CeO2 system as a photo-catalyst and chemical sensor.

EFFECT OF NANO-FILLER DISPERSION ON THE THERMAL,MECHANICAL AND WATER SORPTION PROPERTIES OF GREEN ENVIRONMENTAL POLYMER

Partially exfoliated nanocomposite （2） has been synthesized by intercalation of poly（propylene carbonate） （PPC） into commercial clay, Cloisite 20B （PPC/C-20B）. Nanocomposite 2 was characterized phiso-chemically and exhibited high thermal, mechanical and anti-water sorption properties as compared to PPC and intercalated nanocomposite （1） of PPC/C- 20B having same amount of clay. TGA results revealed that the thermal decomposition temperature （Td, 50%） of 2 increased significantly, being 40 K and 17 K higher than that of pure PPC and 1, respectively, while DSC measurements indicated that the nano-filler dispersion of 2 increased the glass transition temperature from 21℃ to 31℃. Accordingly, 2 showed high elastic modulus, hardness and anti-water absorption capacity. These thermal, mechanical alad anti-water absorption improvements are of great importance for the application of PPC as packaging and biomaterials.

Synthesis of metal oxide composite nanosheets and their pressure sensing properties

This study presents the synthesis of metal oxides composite nanosheets （oxides of cobalt, zinc and iron） and their pressure sensing properties. A transducer has been fabricated to directly measure the resistance- pressure and impedance-pressure relationships of pristine nanopowder. At the initial stage, a nanopowder sample of 10 mm diameter and 1 mm height was placed in the transducer and by applying pressure of up to 8.15 kN/m^2; the DC resistance and the impedance are reduced by 44% on average. It can be explained by the densification of the samples and a decrease in porosity due to the effect of pressure. It was also observed that the DC resistance increases with time and saturated within 8 min. It is considered that this phenomenon is based on the effect of displacement currents of bound charges. The dependences of the impedance phase （8） on frequency and pressure have also been investigated.