不同晶型Bi2O3可见光光催化降解罗丹明B的研究

采用化学沉淀法制备了α、β、γ 3种晶体结构的Bi₂O₃光催化剂。利用XRD、TEM、氮气吸附、TG-DSC、紫外-可见漫反射光谱对样品的晶体结构、微观形貌、光学吸收特性进行了表征，并以罗丹明B(RhB)作为模型污染物，研究了不同的粉体光催化剂在可见光(λ>420 nm)照射下的光催化能力。结果表明：制备的α-Bi₂O₃为长3 μm、宽1 μm的板条状颗粒，带隙为2.84 eV；β-Bi₂O₃为粒径约150 nm的不规则颗粒，带隙为2.75 eV；γ-Bi₂O₃为直径6 nm、长度150~200 nm的纳米管，带隙为2.68 eV。在可见光照射下Bi₂O₃光催化降解RhB的活性如下：γ-Bi₂O₃>β-Bi₂O₃>α-Bi₂O₃，其中γ-Bi₂O₃在辐照60 min后对罗丹明B的脱色率可达97%以上。

Visible-Light Photocatalytic Degradation of RhB by Bi2O3 Polymorphs

The α, β, and γ-Bi_2O_3 were obtained by a chemical precipitation method. The crystal structures, morphologies and optical properties of Bi_2O_3 polymorphs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption method, thermal gravimetry-differential scanning calorimetry (TG-DSC) and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). The photocatalytic performance of Bi_2O_3 was evaluated using rhodamine B (RhB) as a model pollutant under visible light illumination (λ>420 nm). The result showed that the lath-shaped α-Bi_2O_3 with a band gap of 2.84 eV was 3 μm in length and 1 μm in width; the irregular β-Bi_2O_3 with a band gap of 2.75 eV had a particle size of approximately 150 nm; the nanotube γ-Bi_2O_3 with a band gap of 2.68 eV was 6 nm in diameter and 150 nm to 200 nm in length. The photocatalytic degradation of RhB by Bi_2O_3 polymorphs under visible light illumination were as follows: γ-Bi_2O_3>β-Bi_2O_3>α-Bi_2O_3. The T-Bi_2O_3 nanotube exhibited the best photoeatalytic performance which can effectively degrade 97% RhB within 60 min.