Study On The Synthesis Of Novel Pyrochlore Phase Antimonate And Its Photocatalytic Performance

Semiconductor photocatalyst has attracted significant attention and has enormous potential for application in environment remediation and selective organic synthesis.TiO2 photocatalyst was widely studied and used for its stablility,nontoxicity and high efficiency.However,TiO2 has low quantum efficiency and cannot be motivated by visible light,which restricts its large-scale application in industrialization.Therefore,the search for alternate photocatalysts with higher efficiency and appropriate bandgap is an important issue and exhibits a significant importance for sustainable development in photocatalytic field.Recently,some pyrochlore-typed photocatalytic materials attracted more and more attentions.Due to the open structure,their composition and crystal structure are easy to be modified for improving the mobility of photogenerated carriers,which is crucial to enhance the photocatalytic activity.Our research group has developed a kind of defect pyrochlore photocatalyst(Sr1.21Sb2O6.18)with excellent photocatalytic activity under ultraviolet illumination,which was much stronger than that of P25.The quantum efficiency was about 20%in the degradation of benzene.However Sr1.2Sb2O6.18cannot be stimulated by visible light for its large bandgap.Thus,this study focused on improving the utilization of sunlight over antimony strontium materials and developing novel antimonate material with the efficient utilization of visible light.In this paper,a novel antimonate material with visible photocatalytic activity was prepared by a facile ion-exchanged method.The photocatalytic activities were investigated by reduction of azo dyes and photocatalytic reduction of nitroaromatic compounds.A possible mechanism was expatiated.In addition,the relationship between the crystal water in lattice and the photocatalytic activity of SrSbO has been explored in the thesis.The main conclusions obtained are as follows:(1)Sn2+-substituted Sr1.21Sb2O6.18(SnSbO)was obtained via a facile hydrothermal method.The bandgap was reduced from 4.5 to 2.4 eV by Sn2+-substituted.The average particle size of the material was 13 nm.(2)SnSbO showed excellent activity for photocatalytic reduction of azo dyes and nitroaromatic compounds.The photogenerated electrons were the driving species.(3)The crystal water in lattice of Sr1.21Sb2O6.18 may be one of important factors for its high photocatalytic activity.The innovations of this paper are as follows:(1)A novel antimonate material,Sn2+-substituted Sr1.21Sb2O6.i8,was obtained by a facile ion-exchanged method.It is firstly reported to apply in photocatalytic selective reduction of nitroaromatic compounds to corresponding amines.(2)A possible mechanism was proposed for crystal water in pyrochlore-type promoting the separation of photogenerated carriers.