Facets Regulation And Defects Engineering Modify TiO₂ And Performance And Mechanism Research Of Photocatalytic Degradation Of Anthracene

Polycyclic aromatic hydrocarbons（PAHs）are a kind of toxic and carcinogenic organic pollutants which are ubiquitous in different environmental media.The PAHs pollution in water is becoming more and more serious with the rapid industrial development.Photocatalytic degradation is an efficient way to remove such kind of persistent pollutants,and TiO₂ has become the most widely used catalyst material.Nevertheless,as well as the high recombination efficiency of photoinduced electron-hole pairs,TiO₂ with the wide band gap can only use ultraviolet light lowing the photocatalytic efficiency and restricting practical application of TiO2.In this study,facets regulation and defect disorder technologies were introduced to fabricate TiO₂ with different exposed facets using hydrothermal method and defective TiO₂ with different concentration of oxygen vacancies annealed under different conditions.Thus,the photodegradation efficiency of organics can be improved substantially by using the above TiO2 catalyst materials.In this study,firstly anthracene was photocatalytic degraded using anatase TiO₂ with different dominant exposed facets as catalyst under simulated sunlight.The facet dependent photocatalytic activity and intermediate production during degradation of anthracene were studied.The results demonstrate that the photodegradation of anthracene follows first order reaction kinetic model,and the degradation rate of anthracene follows the order{101}>{010}>{001}-TiO₂.The photodegradation pathway of anthracene is investigated.Anthraquinone and anthranone are the main intermediate products formed during the reaction by means of GC-MS measurement.It is comfirmed that holes and oxygen rather than OH radical are the main active species playing roles in the photodegradation of anthracene.For{001}faceted TiO₂,holes generated and accumulated on this facet promote the degradation of anthracene and formation of anthraquinone.While for{101}faceted TiO₂,oxygen absorbed on the facet acts as electron acceptor and forms superoxide radical,which then oxidizes the pollutants.In addition,defective TiO₂ with different concentration of oxygen vacancies annealed under different conditions were also used as catalysts to photodegradate anthracene.The oxygen vacancy production and its relation with thermal treatment time,ability of producing active radicals under simulated solar irradiation,and the photocatalytic performance and mechanism of defective TiO2 on degradation of anthracene were studied in this study.The results showed that TiO₂ introduced with oxygen vacancies showed superior catalytic activity than the origincal TiO₂ during the degradation of anthracene,at the same time,the photocatalytic activity of TiO2 with different concentration of oxygen vacancies were consistent with the order of concentration of produced·OH.Through the comparative analysis,the introduction of appropriate oxygen vacancies in TiO₂nanomaterials could probably trap the electrons and improve the separation efficiency of photoinduced electron-hole pairs.This facilitated the production of more reactive oxygen species so as to improve the photodegradation efficiency of anthracene.