不同晶相Bi_2O_3粉体的制备与表征

Preparation and characterization of Bi_2O_3 powders with different crystal structures

以Bi(NO_3)_3·5H_2O为主要原材料,利用共沉淀法制备α、β、γ3种不同晶相的Bi_2O_3粉末。利用X射线衍射、扫描电镜、紫外-可见光分光光度计对样品进行表征,结果表明:制备的α-Bi_2O_3粉末为长条状颗粒,β-Bi_2O_3粉末为不规则颗粒状,γ-Bi_2O_3粉末呈现为四面体颗粒。以质量浓度为10 mg/L的罗丹明B溶液为降解目标,考查不同晶相Bi_2O_3对罗丹明B的光催化降解性能,发现γ-Bi_2O_3粉末的光催化性能最佳,降解效率可达62. 5%。利用第一性原理对α、β、γ3种晶相Bi_2O_3的能带结构进行计算,计算结果表明:3种晶相Bi_2O_3的导带均主要由O 2p轨道构成,价带主要由Bi 6p轨道构成。光催化过程中,电子可从价带跃迁到导带参与化学反应,从而使罗丹明B溶液发生降解。

Using Bi(NO3)3·5H2O as main raw material,Bi2O3 powders with different crystal structures named as α,β,γ respectively were prepared using the co-precipitation method.The samples were characterized by X-ray diffraction,scan electron microscopy and UV-Vis spectrophotometer.The results indicate that α-Bi2O3 powders are in the shape of long strip,β- Bi2O3 powders are in irregular granules shape and γ-Bi2O3 powders are in the shape of tetrahedron.Using10 mg/L Rhodamine B solution as photo catalysis target,photo catalysis activities of Bi2O3 with three different crystal phases are eval.γ-Bi2O3 powders possess the best performance,whose photo catalysis degradation of Rhodamine B can reach 62.5%.Band structures of three different crystal phases of Bi2O3 are calculated by the first-principles.The calculated results show that the valence band of three Bi2O3 are mainly composed of O 2p orbitals and conduction band are mainly composed of Bi 6p orbitals.The electrons can be excited to conduction band from valence band so as to participate in the chemical reactions which result in the photo degradation of the Rhodamine B solution.