水热法原位合成磁性BiFeO3-石墨烯杂化材料及其光催化性能

Hydrothermal synthesis of magnetic graphene-BiFeO3 hybrids and their photocatalytic properties

  • 摘要: 采用水热法在石墨烯表面原位合成了石墨烯含量不同的铁酸铋/石墨烯(BiFeO3-石墨烯)杂化材料。采用X光射线衍射(XRD)、扫描电子显微镜(SEM)、傅里叶红外光谱(FTIR)等研究杂化材料的结构,紫外漫反射光谱(DRS)和荧光光谱(PL spectra)分析其光反应性。在卤钨灯光照条件下测试杂化材料催化降解亚甲基蓝(MB)和罗丹明B (RhB)染料的性能。结果表明,通过水热原位合成法,石墨烯均匀地穿插在BiFeO3颗粒中并形成大小均一的球状结构。BiFeO3-石墨烯杂化材料在可见光范围(400~800 nm)的吸收强度明显增加,禁带能隙明显降低。BiFeO3-石墨烯杂化材料光催化降解有机污染物的速度较纯BiFeO3显著提高,其中石墨烯质量含量为3%的杂化材料具有最高的降解速度,其光催化降解MB和RhB的速率常数为0.083和0.10,均为纯BiFeO3降解染料速率的10倍以上,原因在于石墨烯有效地抑制并延后了激发电子和空穴的再结合。由于BiFeO3具有铁磁性,BiFeO3-石墨烯杂化材料可以用磁铁回收循环使用,且材料5次循环使用后染料降解效率仍可达到近100%。

     

    Abstract: The graphene-bismuth ferrite (Graphene-BiFeO3) hybrids with different graphene contents were synthesized by a hydrothermal method. Their structure was characterized by XRD, SEM and FTIR. Their light reflection and absorption were investigated by UV-visible diffuse reflectance spectroscopy and photoluminescence spectroscopy, respectively. Their photocatalytic properties were evaluated by degrading methylene blue (MB) and rhodamine B (RhB) dyes under irradiation with tungsten light. Results showed that the hybrids had a sphere-like morphology, within which the graphene was uniformly dispersed between the BiFeO3 spheres. The hybrids had lower band gaps and higher absorption intensities in the visible light region (400-800 nm) than pure BiFeO3, and achieved much higher degradation rates for both MB and RhB. The hybrid with a graphene content of 3.0 wt% exhibited the best photocatalytic performance, and its degradation rate constants for MB and RhB reached to 0.083 and 0.10, respectively, which are about 10 times higher than pure BiFeO3. The introduction of the graphene effectively inhibited the recombination rate of the excited electrons and the holes in BiFeO3. Their magnetism made them easy to recover from the dye solutions and their photocatalytic activities remained unchanged after recycling 5 times.

     

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