Enhanced visible-light responsive photocatalytic activity of Bi25FeO40/Bi2Fe4O9 composites and mechanism investigation

• Published in: Journal of materials science. Materials in electronics 2019-06, Vol.30 (11), p.10923-10933
• Main Authors: Wang, Geming, Cheng, Da, He, Tiancheng, Hu, Yiyu, Deng, Quanrong, Mao, Yangwu, Wang, Shenggao
• Format: Article
• Language: English
• Subjects: Absorption spectra; Catalytic activity; Characterization and Evaluation of Materials; Charge transfer; Chemistry and Materials Science; Composite materials; Electron microscopes; Emission spectra; Field emission microscopy; Fourier transforms; Heterojunctions; Infrared spectra; Infrared spectroscopy; Materials Science; Optical and Electronic Materials; Photocatalysis; Rhodamine; Structural analysis; Transmission electron microscopy; Weight; X-ray diffraction
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-019-01436-4

Pure Bi 25 FeO 40 , Bi 2 Fe 4 O 9 , and different weight ratios of Bi 25 FeO 40 /Bi 2 Fe 4 O 9 composite photocatalysts have been synthesized via a hydrothermal process combined with a mixing-calcination method and evaluated as visible-light responsive catalyst for the degradation of Rhodamine B (RhB). All the as-prepared samples have been characterized by a range of techniques including X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), UV–vis absorption spectra (DSR), Field Emission Scanning Electron Microscope (FE-SEM), Transmission electron microscope (TEM) and High-resolution TEM (HRTEM). The XRD, FT-IR, TEM and HRTEM results confirm that the composite only consists of Bi 25 FeO 40 and Bi 2 Fe 4 O 9 . In the Bi 25 FeO 40 /Bi 2 Fe 4 O 9 composites, closely contacted interfaces have been observed. Compared with the single-phase Bi 25 FeO 40 and Bi 2 Fe 4 O 9 , Bi 25 FeO 40 /Bi 2 Fe 4 O 9 composites exhibit enhanced visible-light responsive photocatalytic activities. The photocatalytic efficiency of optimized Bi 25 FeO 40 /Bi 2 Fe 4 O 9 composite with Bi 2 Fe 4 O 9 weight ratio of 30% is about 8.8 and 6.2 times higher than that of pure Bi 25 FeO 40 and Bi 2 Fe 4 O 9 , respectively. On the basis of electronic energy-band structure analysis, the active species trapping experiments and the electrochemical impedance spectrum (EIS) performance, a heterojunction-type charge transfer mechanism interpreting the enhanced photocatalytic activities of the composite are proposed and discussed. In addition, the effects of different Bi 25 FeO 40 /Bi 2 Fe 4 O 9 weight ratios and their geometry architecture on photocatalytic activities are also thoroughly discussed.