Investigation Of Photocatalytic Activity Enhancement For TiO₂ Nano-flowers And NiS/TiO₂ P-n Heterojunction Nanosheets Array Films

In this thesis,first,briefly summarized the research significance and the present situation of semiconductor photocatalysis,described the photocatalytic mechanism of semiconductor photocatalysis,reviewed and analyzed the current progress and suffering problems about the TiO2.Then,emphatically summarized the author’s research work titled “Investigation of photocatalytic activity enhancement for TiO2 nano-flowers and NiS/TiO2 p-n heterojunction nanosheets array films” undertaken during studying for Master’s degree.The specific research results were presented as follows:1.Different sheet-like TiO2 nano-flowers(NFs)exposed(001)crystal face were successfully synthesized by one-step hydrothermal growth method,using tetrabutyl titanate,isopropanol and anhydrous ethanol as solvent,KF as morphology control agent.Our investigation for photocatalytic degradation methyl orange(MO)under simulated sunlight irradiation suggested that the optimal 0.01KF-TiO2 NFs dramatically enhanced photocatalytic activity,and their degradation efficiency was nearly 2.3 times higher than that of commercial P25.The improved photocatalytic performance of the TiO2 NFs was attributed to the flower-structure and the exposed(001)crystal plane,which can provide more active surface and larger specific surface area.2.NiS nanoparticles were successfully loaded on TiO2 nanosheet arrays(NSAs)through a two-step hydrothermal process,and NiS/TiO2 p-n heterostructure NSAs were used to carry on the photocatalytic degradation of MO experiments.The results showed that 0.003-NiS/TiO2 p-n heterostructure NSAs dramatically enhanced the photocatalytic activity,and their degradation efficiency was nearly 2.34 times higher than pure TiO2 NSAs structure.After 4 cycles,the degradation rate of MO maintained above 65%,showing perfect reusability and superior stability.The good photocatalytic performance of the novel NiS/TiO2 p-n heterojunction NSAs was attributed to the the built-in electric field between TiO2 and NiS,the good electrical conductivity of NiS and matched level between NiS and TiO2.