球状BiOCl/Bi_2O_3异质结的制备及其吸附性能研究

Study on fabrication and adsorptive performance of spherical BiOCl/Bi_2O_3 heterojunction

以立方块体Bi_2O_3为原料,利用超声辅助酸浸法合成了BiOCl/Bi_2O_3异质结.采用XRD、SEM、BET、UV-Vis等分析方法分别对样品的晶体结构、微观形貌、比表面积和光学特性进行表征.以RhB为目标降解物研究了样品的吸附性能以及在可见光照射下的光催化降解性能.结果表明,立方晶相立方块体结构的Bi_2O_3在超声辅助酸浸法处理后转变成介孔的球状结构,片状结构的BiOCl附着于球体的表面.介孔球状的BiOCl/Bi_2O_3在30min暗吸附作用后,对RhB的吸附率达到56.22%,为Bi_2O_3吸附率的4.2倍,这是由于构建异质结后比表面积增大,且形成了介孔结构,但其在可见光下对RhB无光催化降解活性,原因在于所构建的异质结为Ⅰ型异质结结构,载流子全部转移并聚集在了Bi_2O_3上,抑制了载流子的分离,降低了BiOCl/Bi_2O_3异质结光氧化还原的能力.

BiOCl/Bi2 03 heterojunction was synthesized by the ultrasound assisted acid etching method, using cubic Bi2O3 as a raw material. The crystal structure, microstructure, specific area, optical property of samples were characterized by X ray diffractometry （XRD）,Scan ning electron microscopy （SEM）,BET surface analyzer and Ultraviolet visible spectroscopy （UV Vis）,respectively. RhB was also used as a model pollutant to investigate the adsorptive performance of samples and their photocatalytic degradation performances under visible light irradiation. The results indicate that the prepared cubic Bi2O3 with a cubic phase is trans formed into mesoporous sphere and BiOCl sheets are adhered to the surface after the ultrasound assisted acid etching method. Stirred in the dark for 30 rain, the adsorption rate for RhB of the fabricated mesoporous spherical BiOCl/Bi2O3 reaches 56. 22% ,4. 2 times more than the adsorption rate of Bi2O3 ,which can be attributed to the larger specific surface area and mesoporous structure. However,there is no photocatalytic degradative activity of BLOCl/ Bi2O3 for RhB under the visible light because the prepared heterojunction is a Type I hetero junction,on which the charge carriers are transferred and accumulated on Bi2O3, inhibiting the separation of carries and reducing the photocatalytic redox ability of the heterojunction.