Ce掺杂Bi_2O_3光催化剂的制备、表征及其可见光催化性能

Preparation,Characterization and Visible-light-responsive Photocatalytic Activity of Cerium-doped Bismuth Oxide

采用水热-焙烧法制备了Ce掺杂的可见光响应的Bi2O3光催化剂(Ce-Bi2O3)。利用XRD、FT-IR、XPS和UV-Vis对不同Ce-Bi2O3样品进行了表征分析,并以光催化降解金橙Ⅱ溶液为探针反应,考察了Ce-Bi2O3的可见光催化性能。结果表明,Ce掺杂可以减小催化剂的禁带宽度,使光谱响应范围向可见光拓展。掺杂的Ce可取代Bi2O3晶格中部分Bi,形成Bi—O—Ce键,并生成了少量铈铋复合氧化物(Bi7.38Ce0.62O12.31),它们的存在有效地抑制了光生电子-空穴对的复合,有助于提高Bi2O3的可见光催化活性。但焙烧时间过长将导致Ce-Bi2O3催化剂的表面发生烧结现象,致使其催化活性降低。可见光照射下的金橙Ⅱ光催化降解实验表明,经2 h焙烧后得到的Ce/Bi的量比为0.5的Ce-Bi2O3催化剂具有最佳的光催化活性。

Ce-doped Bi2O3 photocatalysts with different molar ratio were prepared by the hydrothermal process,and then calcined at 600 ℃ for hours.The Ce-Bi2O3 photocatalysts were characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopic(XPS),and ultraviolet-visible spectrophotometry(UV-Vis),respectively.The photocatalytic properties of Ce-Bi2O3 were evaluated by the photo-degradation of acid orange Ⅱunder visible light irradiation.The results show that the doping of Ce can decrease the band gap of Bi2O3 significantly,and extend the visible light absorption.The doped Ce partially substitutes Bi in the lattice of Bi2O3,which exists in the form of Bi—O—Ce chemical bond.Meanwhile,a new complex metal oxide compound(Bi7.38Ce0.62O12.31) appears in the catalysts,which can separate the electron-hole pairs and improve the photocatalytic performance.The results also indicate that the catalyst can be sintered with the extension of calcination time,resulting in lower catalytic activity of Ce-doped Bi2O3.Generally,the Ce-doped Bi2O3 samples with the Ce /Bi molar ratio of 1∶ 2 calcined at 600 ℃ for 2 h possess the great photocatalytic activity for acid orange Ⅱ.