g-C_3N_4/BiFeO_3复合可见光催化剂的制备及其光催化性能

Preperation and Photocatalytic Performance of Visible-Light-Driven g-C_3N_4/BiFeO_3 Composite Photocatalysts

采用微波溶剂热法和简单的固相热分解反应成功制备了g-C_3N_4/BiFeO_3/BiFeO_3复合可见光催化剂,利用扫描电子显微镜(SEM)、X射线衍射光谱仪(XRD)、傅里叶变换红外光谱仪(FT-IR)和紫外可见漫反射光谱(UV-Vis DRS)等技术对所制备的催化剂进行了表征。结果显示,复合可见光催化剂保持BiFeO_3的钙钛矿结构,g-C_3N_4/BiFeO_3只是复合在BiFeO_3的表面,没有改变BiFeO_3的晶体结构;UV-Vis DRS测试显示,g-C_3N_4/BiFeO_3/BiFeO_3的吸收带边发生了红移,可见光吸收能力得到提升。g-C_3N_4/BiFeO_3和BiFeO_3形成的异质结结构,很好地抑制了光生电子-空穴对的复合率;以罗丹明B为目标降解物,研究了催化剂的可见光催化性能。结果表明,g-C_3N_4/BiFeO_3和BiFeO_3的复合可以显著地提高催化剂的可见光催化活性;在g-C_3N_4/BiFeO_3的掺入量为15%时,g-C_3N_4/BiFeO_3/BiFeO_3对罗丹明B的可见光催化降解率可以达到93.62%。

g-C3N4/BiFeO3/BiFeO3 heterojunction photocatalysts are synthesized by microwave solvothermal technique and solidstate pyrolytic reaction. The as-prepared samples are characterized by scanning electron microscopy（SEM）, X-ray diffraction（XRD）, fourier transform infrared spectrometer（FT-IR）, UV-Vis diffuse reflectance spectra（UV-Vis DRS）. The results show that the photocatalyst maintains the perovskite phase constructure of BiFeO3,g-C3N4/BiFeO3 exists only on the surface, and has no effect on the crystal structure of BiFeO3; UV-Vis DRS test showed that the g-C3N4/BiFeO3/BiFeO3 absorption band edge red shift and its visible light absorption ability get promoted. The formation of g-C3N4/BiFeO3/BiFeO3 heterojunction can effectively restrain the recombination rate of photo-induced electron-hole pair and result in an increase in visible-light photocatalytic activity. The photocatalytic activities of samples are examined by monitoring the degradation of rhodamine B in an aqueous solution under solar light radiation. Results show that the compound of g-C3N4/BiFeO3 and BiFeO3 can significantly improve the visible light catalytic activity of the catalyst. The degradation rate of rhodamine B can reach 93.62% when the mixing amount of g-C3N4/BiFeO3 is 15%.