Controlled Synthesis And Performance Characterization Of Nanostructured Metal Oxide Semiconductor Nanomaterials

Metal oxide semiconductor nanomaterials have been widely used in many fields such as catalysis,gas sensors,solar cells et al.because of its unique physical chemical properties,and easily controllable morphology,microstructure,constituent,crystal growth direction.Therefore,the design and fabrication of environmental catalytic materials and gas sensitive materials with high performance,simple process,low-cost and environmental-friendly have attracted considerable attention.Herein,we researched the synthesis of TiO2,?-Fe2O3,ZnO and ZnO-SnO2 heterojunction based on the microstructure and composition regulation of metal oxide semiconductor materials.Then we explored the photocatalytic performance to organic pollutants(Rhodamine B)and the gas sensitive to ethanol gas.Meanwhile we analyzed the mechanism of photocatalysis and gas sensitivity.The results were as follows:(1)Carbon spheres were prepared by hydrothermal method with glucose as carbon source.With the increase of glucose concentration,the size of the carbon spheres increased after 9 h reaction at 180 ?.It was found that the monodispersed,smooth surface carbon spheres with a diameter of 394 nm were obtained with 0.5 mol/L glucose.When the hydrothermal reaction time was extended to 12 h,the carbon spheres showed serious agglomeration.The results indicated that the hydrothermal reaction time and the concentration of glucose can regulate the size and dispersion of carbon spheres.(2)TiO2 hollow spheres with high photocatalytic performance were successfully prepared by using carbon spheres as templates and tetrabutyl titanate as titanium source.The thickness of TiO2 hollow spheres can be controlled by the addition of tetrabutyl titanate.The TiO2 hollowspheres with a shell thickness of 25 nm were synthesized with the addition of 1 m L tetrabutyl titanate,and the photocatalytic degradation rate was about 0.1539 min-1.When tetrabutyl titanate was 2 mL,shell thickness increase to 35 nm,and the photocatalytic degradation rate was about 0.0861 min-1.The results showed that the increase of the thickness of TiO2 hollow spheres will lead to the decrease of photocatalytic activity.(3)We successfully realized the control of the ?-Fe2O3 nanostructures with using wet chemical methods(template method and hydrothermal method),and studied the effect of morphology on the gas sensing properties of ?-Fe2O3.?-Fe2O3 hollow spheres with a diameter of 300 nm prepared by template method have the sensitivity(14.8)to 100 ppm ethanol at 300 ?,and the response-recovery time were 6 s/21 s.?-Fe2O3 nanoparticles and spindles were sensitive to 100 ppm ethanol was 4.2 and 6.1 at 300 ?,respectively.Compared with the ?-Fe2O3 spindles and particles,?-Fe2O3 hollow spheres exhibited the highest gas sensing properties.(4)Zinc Oxide with morphology of nano hollow spherical shell and nanorods were prepared by template method.It was found that the ZnO hollow spheres had better photocatalytic degradation ability than ZnO nanorods.The ZnO hollow spheres had a diameter about 30 nm when zinc acetate concentration at 0.057 mol/L,and the photocatalytic degradation was 92.51% after 50 min illumination.The ZnO hollow spheres had a diameter about 180 nm when zinc acetate concentration at 0.171 mol/L,and its photocatalytic degradation was 99.43% after 50 min illumination.Besides the photocatalytic degradation rate was about 0.097 min-1.The catalytic degradation of ZnO nano hollow spherical shell and nanorods compound was 91.72% after 50 min illumination,when zinc acetate concentration at0.285 mol/L.The results showed that the amount of zinc acetate can regulate the morphology of the product,and the hollow structure of the ZnO had higher photocatalytic performance.(5)We prepared ZnO-SnO2 heterojunction with excellent properties of photocatalytic and gas sensing by template method.The ZnO-SnO2 hollow spheres have good microstructure and priorities,whose diameter was 180 nm,and particle size composition of spherical shell was about 7 nm when the carbon spheres at 0.2 g,zinc acetate concentration at 0.057 mol/L,stannic chloride at 0.036 mol/L.The gas sensitivity to 100 ppm ethanol was 42.2 at 300 ?,and the response-recovery time was 6 s/11 s,respectively.Compared with the ZnO,ZnO-SnO2 hollow spheres showed better photocatalytic performance,and the photocatalytic degradation rate of rhodamine B was 0.125 min-1.