Fe₃O₄/BiOBr光催化固氮性能研究

Investigation on the Photocatalytic Performance of Fe₃O₄/BiOBr of Fixing Nitrogen

摘要: 本文先以FeCl₃与FeSO₄∙7H₂O为原料采用氨水为沉淀剂共沉淀制备了Fe₃O₄,再以Bi(NO₃)₃∙5H₂O与KBr为原料加入Fe₃O₄采用水热法制备了不同含量Fe₃O₄复合BiOBr催化剂。并用X射线衍射仪、紫外–可见光谱漫反射仪和电化学工作站等仪器研究了催化剂的物相、吸光性能和阻抗，并考察了Fe₃O₄/BiOBr光催化固氮性能。结果表明，随着Fe₃O₄含量的增加，复合催化剂的吸光能力增强，带隙减小，阻抗减小，使光生电子移动速率加快，催化剂的平带电位减小，催化剂的还原能力增加，更易活化氮分子，更易与氢离子生成铵根离子，Fe₃O₄/BiOBr固氮性能越高。当反应时间为130 min，BiOBr与Fe₃O₄的物质的量之比为1:0.5，催化剂的质量为0.2 g时，Fe₃O₄/BiOBr光催化固氮性能最好，催化剂的效率为10.51 μg∙g⁻¹∙min⁻¹。

Abstract: In this paper, Fe₃O₄ was prepared by co-precipitation of FeCl₃ and FeSO₄∙7H₂O with ammonia as the precipitant, and then Fe₃O₄ composite BiOBr catalysts with different contents of Fe₃O₄ were prepared by hydrothermal method with the addition of Fe₃O₄ from Bi(NO₃)₃∙5H₂O and KBr as the raw materials. The physical phases, light-absorbing properties and impedance of the catalysts were also investigated by X-ray diffractometer, UV-visible spectral diffuse reflectometer and electrochemical workstation, and the photocatalytic nitrogen fixation performance of Fe₃O₄ composite BiOBr was examined. The results showed that with the increase of Fe₃O₄ content, the light-absorbing ability of the composite catalyst was enhanced, the band gap was reduced, the impedance was reduced, so that the rate of photogenerated electron movement was accelerated, the flat-carrying potential of the catalyst was reduced, the reducing ability of the catalyst was increased, it was easier to activate the nitrogen molecules, it was easier to generate ammonium root ions with the hydrogen ions, and the higher the nitrogen fixation performance of the Fe₃O₄ composite BiOBr was. The photocatalytic nitrogen fixation performance of Fe₃O₄ composite BiOBr was the best when the reaction time was 130 min, the ratio of the substance amounts of BiOBr to Fe₃O₄ was 1:0.5, and the mass of the catalyst was 0.2 g. The catalytic efficiency of Fe₃O₄ composite BiOBr was 10.51 μg∙g⁻¹∙min⁻¹.