分级多孔结构Bi2WO6/TiO2纳米材料的生物模板法制备及其光催化性能

Hierarch porous Bi2WO6/TiO2 nano-material synthesized with biological template and its photocatalytic performance

本文以玉米秸秆为生物模板,高温焙烧制备了具有玉米秸秆分级多孔结构的纯相二氧化钛(TiO2),再通过水热法制备了钨酸铋(Bi2WO6)/二氧化钛(TiO2)复合催化材料.运用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)及紫外可见(UV-vis)漫反射等手段对催化材料的组成和微观结构进行了表征分析.结果表明,通过高温焙烧法制备的样品为纯相锐钛矿型TiO2,TiO2表面呈片状结构,通过多孔道相互联结形成多孔蜂窝结构,Bi2WO6呈花球状附着在TiO2表面,形成Bi2WO6/TiO2复合材料.以氙灯为光源,采用罗丹明B作为光催化降解污染物评价复合催化材料的光催化性能.结果表明:相较于纯相TiO2材料,Bi2WO6/TiO2复合材料在可见光下表现出对罗丹明B较好的催化活性.在氙灯光照射120min后,采用模板法制备的Bi2WO6/TiO2对罗丹明B的降解率高于无模板制备的Bi2WO6/TiO2复合材料,分别为99.3%和81.7%.在Bi2WO6/TiO2掺杂比为1∶2时,复合光催化材料表现出的光催化活性最好,并且在溶液pH=6、复合光催化材料投加量为0.4g时降解效果最佳.复合催化剂的光催化活性的提高主要由于Bi2WO6和TiO2形成了异质结构,提高了光生电子-空穴对的分离效率.

Hierarchical porous titanium dioxide(TiO2)nano-material was prepared using corn straw as biological template via high temperature calcination.Next,hydrothermal method using bismuth tungstate(Bi2WO6) form a composite catalytic material Bi 2WO 6/TiO2.The catalytic materials were analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS) and ultraviolet-visible(UV-vis) diffuse reflectance.The results show that the sample prepared by high temperature calcination is pure anatase TiO2 with corn straw biological template completely removed.The surface of TiO2 samples show sheet-like structure and is formed by the interconnection of porous channels to form a porous honeycomb structure.Using Xenon lamp as the light source,Rhodamine B was used as photocatalytic degradation pollutant to evaluate the photocatalytic performance of the composite catalytic material,and the reaction mechanism was analyzed.The results show that the Bi 2WO 6/TiO2 composite exhibits better catalytic activity for Rhodamine B under visible light than pure phase TiO2.The degradation rate of Rhodamine B by Bi 2WO 6/TiO2 prepared by template method was significantly higher than that of Bi 2WO 6/TiO2 composite without template preparation after 120 min illumination of xenon lamp,which were 99.3 % and 81.7 %,respectively.Thephotocatalytic activity of composite photocatalytic materials is best when the doping ratio of Bi2WO6/TiO2 is 1∶ 2.And the degradation effect is best when the solution pH=6 and the compound photocatalytic material dosage is 0.4 g.The improvement of the photocatalytic activity of the composite catalyst is mainly due to the formation of a heterojunction of Bi2WO6 and TiO2,which improve the separation efficiency of the photogenerated electron-hole pairs.