Effect Of Doping And Heterojunction On The Photocatalytic Activity And Mechanism Of?BiO?₂CO₃

Recently,semiconductor photocatalysts have been received greatheir applications in environmental pollution mediation and solar attention due to their applications in environmental pollution mediation and solar energy conversion.As a novel semiconductor photocatalyst?BiO?₂CO₃,it has become one of the potential photocatalysts owing to its special layered structure and the excellent photocatalytic performance.However,pure?BiO?₂CO₃ with a large band gap can only be excited by UV light,which severely restricts the use of solar light.Therefore,the aim of this thesis is to design visible-light-induced?BiO?₂CO₃with high photocatalytic activity through ion doping and heterostructure building,and to study the enhancement mechanism of photocatalytic performance through the systematcial characterizations.The main research contents and the important results of this thesis are presented as follows:?1?Novel I-?BiO?₂CO₃ photocatalyst was prepared by a facile chemical precipitation method.XRD,SEM,EDS,DRS,XPS and SPV were employed to systematically study the property samples.The photocatalytic activity of I-?BiO?₂CO₃ was estimated by degrading rhodamine B and dichlorophenol under visible light??>400 nm?.The improved photocatalytic activities of I-?BiO?₂CO₃could be mainly attributed to the broad visible light absorption of I-?BiO?₂CO₃,originated from the newly formed I-impurity levels on the top of valence band of?BiO?₂CO₃.?2?Novel Bi OI/I-?BiO?₂CO₃ heterojunction photocatalysts were in situ prepared by etching I-?BiO?₂CO₃ precursor with HI acid.The photocatalytic activities of Bi OI/I-?BiO?₂CO₃ heterojunction photocatalysts were evaluated by the degradation of methyl orange and phenol under visible light??>400 nm?.The results show that the photocatalytic performance of Bi OI/I-?BiO?₂CO₃ was higher than those of?BiO?₂CO₃,I-?BiO?₂CO₃,Bi OI and Bi OI/?BiO?₂CO₃.The enhanced photocatalytic activity of Bi OI/I-?BiO?₂CO₃ mainly resulted from the intensive visible lightabsorption by doping I-ions and excellent separation rate of photocharges through Bi OI/?BiO?₂CO₃ heterojunction interface.?3?Z-scheme photocatalyst Ag I/Ag/I-?BiO?₂CO₃ was synthesized by a photoreduction method.Under visible light??>400 nm?,the photocatalytic activity of Ag I/Ag/I-?BiO?₂CO₃ was investigated by using rhodamine B as a pollutant model.The results showed that the as-prepared Ag I/Ag/I-?BiO?₂CO₃ composites exhibited largely enhanced activity for degrading rhodamine B in comparison with?BiO?₂CO₃,I-?BiO?₂CO₃,Ag I/Ag/?BiO?₂CO₃ and Ag I/Ag.The corresponding kapp value of Ag I/Ag/I-?BiO?₂CO₃ was calculated to be 0.63 h-1.The dramatic activity enhancement of Ag I/Ag/I-?BiO?₂CO₃ was attributed to the high separation efficiency of electron-hole pairs through a Z-scheme heterostructure.