Microwave-hydrothermal Synthesis Of Zno And SnO₂Nanostructured Materials And Their Applied Research

Well monodispersed ZnO nanospheres and SnO₂microspheres weresynthesized under microwave hydrothermal conditions. The chemical structureand surface morphology of the as-prepared samples were characterized byX-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmissionelectron microscopy （TEM） and fourier transform infrared （FT-IR）. Theprocessing factors （such as reaction time, temperature and concentration ofreactants） on the morphology of samples were studied systematically，and theirgrowth mechanism were also initially explored. Besides, the photocatalyticactivities of the the SnO₂microspheres were evaluated by the degradation ofrhodamine B （RhB） in different pH values under UV-light illumination. Inaddition，we were successfully assembled the dye-sensitized solar cells （DSSC）,in which ZnO and SnO₂were used as the anode materials, Pt and activatedcarbon were used as the cathode materials. The photovoltaic performane ofDSSCs were also tested by digital multimeter.The conclusions of this study are as follows:（1） ZnO nanospheres with an diameter of150nm were prepared by usingtriethanolamine （TEA） as complexant and znic nitrate hexahydrate（Zn（NO3）2·6H2O） as znic source under microwave hydrothermal conditions.TEM observations indicate that each ZnO nanosphere is composed of numerousZnO aggregates nanocrystallines with diameters of10-20nm. Moreover, thestructure of ZnO nanospheres is loose. The products obtained at differenttemperatures （140-180℃） and different times （1-60min） have the similarmorphologies under the otherwise identical conditions. The size of the ZnOnanospheres can be adjusted by changing the amount of water and ethanol in thesolution systems.（2） The SnO₂microspheres （1-1.5μm） were successfully prepared bymicrowave hydrothermal method, in which poly（ethylene glycol）（PEG） were used as template, SnCl4·5H2O was used as tin source. TEM observationsindicate that each solid microsphere is aggregated with numerous nanocrystalsand the surface of microspheres is smooth.（3） The photocatalytic activities of the the SnO₂microspheres wereevaluated by the degradation of rhodamine B （RhB） in different pH valuesunder UV-light illumination. Results demonstrate that the pH value of RhBsolution influences the degradation process as well as the adsorption mode.（4） The SnO₂film （5μm） and ZnO film （3μm） were prepared by usingacetylacetone （CH₃COCH₂COH₃） as emulsifier and Triton X-100as dispersant.Under irradiation of simulation sunlight （100mW/cm2）, the DSSC of SnO₂witha short-circuit intensity of0.36mA/cm2, open-circuit voltage of0.792V, fillfactor of0.62and total efficiency of0.17%of was obtained.