Study On The Preparation And Photocatalytic Activity Of ZnSe/ZnO Composite Materials

Environmental pollution and energy crisis are two serious problems.The photocatalytic materials based on ZnO,TiO2 and the other semiconductor oxides have been attracted much attention due to moderate reaction condition,lower secondary pollution,high efficiency and low energy consumption.In this dissertation,ZnSe/ZnO composite materials were prepared and their photocatalytic properties were studied.Nanostructure ZnO was prepared through a simple chemical corrosion process,and it was characterized by scanning electron microscopy,X-ray diffraction and Raman spectra measurement techniques.The prepared nanostructure ZnO was used to investigate the degradation of dye including methyl orange,acid blue and rhodamine B under visible light irradiation.The results show that the microstructure of the obtained ZnO depends on the concentration of H2SO4.Flower-like structures consisting of nanosheets are obtained on zinc plate by 4 min corrosion in 1.67 mol/L and 1.15 mol/L H2SO4 solutions,while nano size ZnO particles are obtained in 3.07 mol/L H2SO4 solution.The flower-like nanostructure ZnO is more effective on the degradation of methyl orange than ZnO nanoparticles.ZnO nanosheets present good degradation on methyl orange and acid blue.Methyl orange is almost completely degraded by ZnO nanosheets in 90 min under visible light irradiation.However,the obtained ZnO exhibits poor photostability.The decomposition ratio decreases to 40%for the second cycle,and it doesn’t present any photocatalytic activity after five cycles.Nanostructure ZnO was prepared by electrochemical method,and it was characterized by scanning electron microscopy,X-ray diffraction measurement techniques.The deposition potential and time on the structure and the photocatalytic properties of films were studied systematically.The results show that the microstructure of the obtained ZnO depends on different electrode.The sword-like nanostructure ZnO is obtained on cathode,while ZnO nanoparticles are obtained on anode under the same condition.ZnO prepared on cathode with deposition time of 3 h shows the highest degradation efficiency under visible light,and 60%methyl orange is degradated in 3 h.The sword-like ZnO nanostructure materials which are prepared on anode with anodic time of 1.5 h and anodic potential of 10 V showed the highest degradation efficiency under ultraviolet light,and 90%methyl orange could be degradated in 4 h.ZnSe films were prepared by electrochemical deposition method,and they were characterized by scanning electron microscopy,X-ray diffraction and Raman spectra measurement techniques.The effects of substrate,deposition potential and time on the composition and structure of films were studied systematically.The photocatalytic properties of these films were also studied.The results show that the substrate has a great influence on the phase composition and morphology of films.Zn substrate is beneficial to prepare ZnSe films.Moreover,the films prepared under the various potentials present different photodegradation rates on methyl orange.The film which is prepared under the potential of-0.6 V with a deposition time of 2 h shows the highest degradation efficiency and 90%methyl orange could be degradated in 6 h.The factors which influence photocatalytic activities are also discussed.ZnSe/ZnO nanocomposites were prepared by the combination of chemical corrosion and electrodeposition methods,and the prepared ZnSe/ZnO nanocomposites were characterized by scanning electron microscopy and X-ray diffraction.The results show that the as-grown ZnSe/ZnO nanocomposites show high degradation efficiency,and 95%methyl orange could be degradated in 80 minutes.The combination of ZnO and ZnSe are good for sperating photogenerated electrons from holes,reducing the composite probability,thereby improving the photocatalytic properties of nanostructure ZnSe/ZnO.