溶剂热法一步合成层状Ag双重修饰Bi_(2)WO_(6)及其可见光催化性能研究

Preparation and Visible Light Catalytic Performance of Layered Ag Double Modified Bi_(2)WO_(6) with One-step Solvothermal Method

以Bi(NO_(3))_(3)·5H_(2)O、Na_(2)WO_(3)·2H_(2)O、AgNO_(3)为原料,采用溶剂热法一步制备Ag掺杂与Ag纳米颗粒双重修饰的Ag/Bi_(2)WO_(6)复合光催化剂。通过XRD、SEM、XPS、TEM、HRTEM、UV-Vis DRS、PL等手段对样品进行结构与性能表征。模拟日光照射条件下,以甲基橙(MO)为降解物,对Bi_(2)WO_(6)和Ag/Bi_(2)WO_(6)的光催化性能和机理进行研究。结果表明,Ag/Bi_(2)WO_(6)具有由纳米片相互堆叠形成的圆形层状结构。Ag在样品中有两种存在形式,一部分以掺杂的方式进入Bi_(2)WO_(6)晶格,一部分以Ag单质纳米颗粒的形式与Bi_(2)WO_(6)复合。Ag修饰使得Bi_(2)WO_(6)的禁带宽度从2.65 eV降到2.25 eV,荧光强度降低。相较于Bi_(2)WO_(6),相同条件下Ag/Bi_(2)WO_(6)对甲基橙具有更佳的降解效果。Ag含量为2%的Ag/Bi_(2)WO_(6)催化降解甲基橙溶液10 min后,降解率达到98.27%,降解速率常数达到0.4359 min^(-1),约为Bi_(2)WO_(6)的10倍,经过五次循环后降解率保持90%以上,稳定性好。Ag的双重修饰拓宽了Bi_(2)WO_(6)的光吸收范围,促进了光生载流子的分离,从而提高了Bi_(2)WO_(6)的光催化性能。

Using Bi(NO_(3))_(3)·5H_(2)O,Na_(2)WO_3·2H_(2)O and AgNO_(3)as raw materials,Ag doped and Ag nanoparticle modified Ag/Bi_(2)_WO_(6)composite photocatalysts were prepared by using a one-step solvothermal method.Structure and properties of the samples were characterized by using XRD,SEM,XPS,TEM,HRTEM,UV-Vis DRS,PL,etc.Under simulated sunlight irradiation conditions,the photocatalytic performance and mechanism of Bi_(2)_WO_(6)and Ag/Bi_(2)_WO_(6)were studied by using methyl orange(MO)for the degradation experiment.The Ag/Bi_(2)_WO_(6)has a circular layered structure formed through the stacking of nanosheets.Ag exists in two forms,entering the Bi_(2)_WO_(6)lattice through doping and incorporation with Bi_(2)_WO_(6)as composite.With Ag modification,the band gap width of Bi_(2)_WO_(6)was reduced from 2.65 eV to 2.25 eV,resulting in a decrease in fluorescence intensity.Compared with Bi_(2)_WO_(6),Ag/Bi_(2)_WO_(6)has high degradation efficiency on the degradation of methyl orange.By using Ag/Bi_(2)_WO_(6)with 2%Ag,the degradation rate reached 98.27%,after 10 min,corresponding to a degradation rate constant of 0.4359 min~(-1),which is about 10 times that of Bi_(2)_WO_(6).Even after five cycles,the degradation rate remained above 90%for Ag/Bi_(2)_WO_(6),indicating its high stability.The dual modification of Ag broadened the light absorption range of Bi_(2)_WO_(6),promoted the separation of photo generated charge carriers,and thus enhanced the photocatalytic performance.