纳米Ag包覆Bi_2O_3颗粒的制备及其可见光催化性能评价

本文采用两步合成工艺,通过化学共沉淀工艺制备β-Bi_2O_3纳米颗粒;经室温原位还原硝酸银,制备不同包覆量纳米Ag负载的Bi_2O_3(Ag/β-Bi_2O_3)光催化剂颗粒。对该光催化剂进行结构表征,并以甲基橙溶液模拟废水在可见光下评价其光催化性能。透射电子显微镜(TEM)测试表明纳米Ag均匀包覆于β-Bi_2O_3颗粒表面,其中β-Bi_2O_3聚集体的颗粒尺寸约30nm,而分散的纳米Ag晶体约为20nm。紫外可见光谱(UV-vis)谱图表明Ag/β-Bi_2O_3复合材料的带隙能比纯相Bi_2O_3要小,对可见光利用率相应增加,光催化性能随之增强。其中以2.0%(质量比)Ag包覆β-Bi_2O_3颗粒的光催化性能最佳。

Synthesis of Nanometer Ag-coated Bi2O3Photocatalyst and Visible Light Responsive Photocatalytic Activity

Two-step synthesis process was proposed,in which β-type bismuth oxide nanoparticles were firstly prepared via coprecipitation process with bismuth nitrate as raw material and aqueous ammonia as precipitator,and then Ag-coated β-Bi2O3(Ag/β-Bi2O3)composite catalysts were synthesized by in-situ reduction process at room temperature.Photocatalytic reaction efficiency under visible light irradiation was evaluated using methyl orange(MO)as simulated pollutant.TEM image shows that nanometer Ag particles with the size of 20nm are uniformly dispersed and coated on β-Bi2O3aggregates 30nm.DRS results show that band gap(Eg)of Ag-coated Bi2O3is less than that of pure Bi2O3.T he utilization rate for visible light and the photocatalytic performances are correspondingly enhanced.Especially 2.0%(in mass ratio)Ag/β-Bi2O3 composite catalyst has the superior photocatalytic degradation efficiency for MO.