| In recent years,the use of semiconductors as photocatalysts has attracted great attention for mitigating the deterioration of environments created by toxic pollutants in water and air.Traditional TiO2 photocatalyst systems have been suffering from poor solar energy utilization and low quantum efficiency on the way of their practicle applications.Therefore,the development of more efficient photocatalysis materials is urgent and indispensable.BiOCl is an important ternary compound because of the coexistence of unique and excellent electrical,magnetic,optical and luminescent properties.Recently,some studies have confirmed that BiOCl exhibits a higher efficiency than TiO2(commercial P25)in the photocatalytic degradation of some dyes in aqueous solution under UV irradiation.However,the high rate of electron-hole recombination still limits BiOCl photocatalysis systems to achieve high enough efficiency.Meanwhile,the BiOCl photocatalyst only make use of UV light,less than 5%of solar energy,because of its high band-gap energy of 3.46 eV.The facet effect is an important factor for heterogeneous photocatalysts,because surface atom arrangement and coordination intrinsically determine the adsorption of reactant molecules,surface transfer between photoexcited electrons and reactant molecules,and desorption of product molecules.Therefore,in this paper,we work along facet-dependent BiOCl nanosheets,aiming to obtain more efficient photocatalysis materials by surface/interface engineering.It's significant and essential to further look into the theory for better understanding of photocatalytic reactions and for rational design and synthesis of photocatalysts with high activity.(1)Facile in situ synthesis of a Bi/BiOCl nanocomposite with high photocatalytic activity:we have developed a UV light-induced chemical reduction route to deposit Bi on the BiOCl nanosheet surface in situ at low temperature.And,the in situ formation of the Bi/BiOCl nanocomposite is proposed.The high photodegradation activity of the Bi/BiOCl nanocomposite can be ascribed to the presence of Bi metal,which can enhance the light absorption intensity,efficiently separate photogenerated electron-hole pairs,and accelerate the interfacial charge-transfer rate.(2)Construction of teethlike homojunction BiOCl(001)nanosheets by selective etching and its high photocatalytic activity:a novel teethlike layered homogeneous structural BiOCl(001)nanosheets is sythesized by selective etching using TEA.With respect to BiOCl(001),T-BiOCl(001)exhibits a superior photocatalytic activity which can be ascribed to the combined interaction of the high UV/vis light harvest,high photogenerated charges separation efficiency,and the fast interfacial charge-transfer rate based on the unique homogeneous topotactic structure.(3)Degradation of 2-Naphthol by facet-dependent BiOCl under Visible Light:we report on photoreactivity for photodegradation of colorless dyes on BiOCl nanosheets exposing(010)and(001)facets.The photocatalytic activities are mainly owing to the formation of surface complex(-Bi-O-C10H7)on the BiOCl surface.The result that BiOCl nanosheet exposing(010)facets exhibit higher activity is due to more surface complex formed on the BiOCl(010)surface that consists of more terminal bismuth atoms.(4)In situ photogenerated defects on surface-complex BiOCl(0 1 0)with high visible-light photocatalytic activity:A probe to disclose the charge transfer in BiOCl(0 1 0)/surface-complex system.In this work,we ingeniously design a facile repeat experiment to obtain reliable information on charge transfer mechanisms and structure-reactivity relationships between surface complex and BiOCl-0 1 0 under reaction condition.Interestingly,this charge transfer gives rise to the formation of defects(Bi3+-O·--Bi3+)which are protected by a disordered outer layer on surface.Moreover,the introduction of defects plays a vital role in photocatalytic and photoelectric performance,which can be verified by DFT calculations. |
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