【摘要】 光催化作为一种环境友好型、低能耗的技术,在环境净化等领域倍受关注.传统光催化剂,如TiO₂, ZnO, V₂O₅和WO₃等具有较高的光敏性,其价格低廉,自然无毒,常用于光电反应的应用当中.然而,这些催化剂具有较宽的禁带宽度,只能在紫外光下响应.为此,设计一种较窄带隙的高可见光活性的光催化剂具有一定的意义.近年来,氯氧化铋光催化剂受到了越来越多的关注,其在紫外光下具有非常优异的光催化性能.并且,研究者们已成功合成出非化学计量比的氯氧化铋,如Bi₃O₄Cl（2.60 eV）,Bi₁₂O₁₇Cl₂（2.10 eV）,Bi12O15Cl6（2.86 eV）和Bi₂₄O₃₁Cl₁₀（2.70 eV）等光催化剂.研究表明,较低的Cl/O比可能会减小催化剂的带隙宽度,并提高其光催化性能;其中Bi₁₂O₁₇Cl₂的Cl/O比最小,是最有潜力的氯氧化铋光催化剂.然而, Bi₁₂O₁₇Cl₂具有较高的光生电子空穴复合率,会极大的减弱其光催化活性.因此,将Bi₁₂O₁₇Cl₂与具有高稳定性,结构相似且空穴复合率低的Bi OCl相结合,将会极大提高在可见光下Bi₁₂O₁₇Cl₂的光催化活性.本文采用了超声水热法成功制备了具有高可见光催化活性的Bi OCl-Bi₁₂O₁₇Cl₂纳米复合材料,用于去除染料和药物废水.扫描电子显微镜和比表面积分析仪的结果表明,纳米复合材料具有良好的分散性,结构为花瓣形状,其平均厚度为20至50 nm,且具有较高的比表面积.紫外-可见漫反射和光致发光光谱分析表明,纳米复合材料具有良好的可见光吸收性能,并且光生电子空穴复合率远低于Bi₁₂O₁₇Cl₂.其在可见光下降解罗丹明B（/环丙沙星）的动力学常数分别约为Bi₁₂O₁₇Cl₂, BiOCl和P25的8.14（/4.94）, 64.66（/11.91）和42.63 （/36.07）倍.合适的形态,结构和光电性能是此纳米复合光催化剂具有优异光催化性能的原因.此外,该催化剂还显示出较宽的pH适用范围和优异的可重复利用性,有利于实际利用.机理研究表明,降解罗丹明B的主要活性物质是光生空穴和超氧自由基.总之,本文开发了一种绿色、稳定、高效的可见光光催化剂,对Bi OCl基的光催化剂的研究作出了一定的贡献.更多还原

【Abstract】 A BiOCl-Bi₁₂O₁₇Cl₂ nanocomposite with a high visible-light response and a low photoinduced electron-hole pair recombination rate was successfully synthesized using an ultrasonic-hydrothermal method. The texture, structure, optical, and photocatalytic properties of the composite were characterized. The results showed that the composite had a sheet flower-like structure with a large specific surface area. Ultraviolet-visible diffuse reflection spectra and photoluminescence spectra showed that the composite had an excellent visible-light response and a low recombination rate of photoinduced electron hole pairs. The photocatalytic property of the composite was evaluated by the removal efficiency of rhodamine B and ciprofloxacin under visible-light illumination. The composite’s reaction rate constant of removing rhodamine B（/ciprofloxacin） was approximately 8.14（/4.94）, 42.63（/11.91） and 64.66（/36.07） times that of Bi₁₂O₁₇Cl₂, P25, and BiOCl, respectively. Furthermore, the composite showed a wide applicable pH range and excellent reusability. Mechanism analysis showed that photogenerated holes played a dominant role and ·O₂^– also contributed to photocatalytic degradation. In summary, this study presents a high-efficiency photocatalyst for wastewater treatment.更多还原