The Mechanism And Visible Light Photocatalytic Research Of Controllable Transformation From Biocl To Bi₂WO₆Superstructure In A New Bi-W-Cl-O Solvothermal System

Among the reported new photocatalytic materials, bismuth-based photocatalyticmaterials with special electronic structure and layered crystal structure, which demonstratesuperior photocatalytic properties, greatly attracted the attention of researchers and hadbecome in recent Nianguang hot research field of catalysis. Besides, the bismuth-basedNanocomposite materials with greater potential application are UV light responsive BiOCland visible light responsive Bi2WO6. Based the analysis which the BiOCl arrangedalternately by [Bi2O2]2+layer and double chlorine atom layers was very similar to thestructure of Bi2WO6composed of alternating [Bi2O2]2++and WO6octahedral layers. Thispaper mainly explored a controllable transformation of BiOCl to Bi2WO6in a newBi-W-Cl-O solvothermal system. Experimental results show that: under the newBi-W-Cl-O system in which glycol as solvent, urea as an additive, Bi(NO3)3as a Bi source,WCl6as both the chlorine source and a tungsten source, the solvothermal temperature andsolvothermal time greatly affected the structure of the product: As the solvothermaltemperature increased or the time extended, the products showed a transformation trendfrom BiOCl to Bi2WO6; The dynamic transformation process experienced three stagesincluding BiOCl, BiOCl/Bi2WO6composites and Bi2WO6with an increase ofsolvothermal time under150oC. We firstly proposes the mechanism that thevisible-light-active three-dimensional (3D) Bi2WO6superstructure was directlytransformed from BiOCl superstructure by substituting the intercalated chlorine atomswith WO6octahedral in Bi-W-Cl-O system via a one-pot solvothermal method, andrevealed the important role of urea for the entire transition process.In this Bi-W-Cl-O system we further successfully synthesis the tungsten dopedBiOCl by one-step solvothermal method. XRD, Uv-vis and XPS results all proved thepresence of W elements in this tungsten doped BiOCl. Furthur studies showed visible photocatalytic performance with different amounts of tungsten. It found that12%Wdoped BiOCl showed the best photocatalytic property and the CO2emissions was almostup to5times the pure BiOCl. This paper provides a new method for modifying BiOCltowards visible light responsive photocatalyst.