光催化材料Bi4O7/BiOBr的制备及其光催化性能研究

以自制的铋酸钾（KBiO₃）为前驱物,采用低温水热法制备七氧化四铋（Bi₄O₇）,再利用氢溴酸原位离子刻蚀法首次成功制备了Bi₄O₇/BiOBr复合物。通过X射线衍射（XRD）和扫描电子显微镜（SEM）分别观测了样品的物相和形貌特征,复合相具有比二者单相更佳的可见光降解罗丹明B（RhB）的性能,最高可达到30 min内降解86.9%;紫外可见漫反射光谱（DRS）和光致发光光谱（PL）分别证明了其性能的提升是由于复合相拥有更广的光学响应范围和更低的光生载流子复合效率。超氧自由基和空穴是该体系光催化降解过程中的活性物质,并由此提出了一种可能的光催化降解机制,且复合相比单相Bi₄O₇具有更好的光催化降解稳定性。     

Photocatalytic properties of BiOX （X = Cl,Br, and Ⅰ）

A novel series of photocatalysts, bismuth oxyhalide （BiOX, X = Cl, Br, and Ⅰ）, were synthesized by a hydrolysis method. The powder sampies were characterized by the use of X-ray diffraction （XRD）, scanning electron microscope, and UV-Vis spectrophotometer. The XRD pattern showed that all the BiOX were well crystallized in the tetragonal structure. The band gaps of the sheet-shaped compounds BiOX （X = Cl, Br, andⅠ） were 3.44, 2.76, and 1.85 eV, respectively. BiOBr showed the highest photocatalytic activity in degrading rhodamine B （RhB） and evolving 02 for its proper valence band （VB）. BiOI has no photocatalytic activity. BiOCl showed the highest activity in decomposing isopropanol because of electron-hole pair separation through trapping electrons by oxygen vacancies.     

Synthesis,characterization and photocatalytic properties of BiOBr/amidoxime fiber composites

BiOBr/amidoxime fiber composite photocatalysts have been successfully prepared via ions chelating on fibers. The structure and composition of the products were characterized by XRD, EDS, SEM, FT-IR, XPS and TG. The results indicated that BiOBr was successfully immobilized on the modified commercial fibers. Photocatalytic testing showed that the BiOBr/amidoxime fiber composites exhibited an excellent recycling performance owing to the coordination interactions between BiOBr and amidoxime fiber.     

煅烧温度、时间和气氛对BiOBr结构和光催化性能的影响

Bi OBr为受热不稳定的半导体。研究了煅烧温度、时间和气氛对Bi OBr结晶度、表面羟基和相变影响。然后考察了催化剂结构变化对可见光催化降解染料酸性橙Ⅱ的活性影响。利用X射线衍射、扫描电镜、紫外可见漫反射光谱、红外光谱等对不同煅烧条件处理后的Bi OBr样品进行了结构、形貌等分析。结果表明,空气气氛下,500℃以下的煅烧处理,可以明显提高Bi OBr的结晶度和光催化活性;在煅烧温度高于520℃时,Bi OBr发生Bi OBr→Bi24O31Br10的转变,在600~650℃煅烧,可产生Bi OBr/Bi24O31Br10混合相,大幅度提高可见光催化活性;在750℃煅烧生成的α-Bi2O3虽然具有较好的可光吸收性能,但是颗粒发生烧结,可见光活性很低。真空气氛煅烧虽然可以提高结晶度,但易导致表面脱羟基,不利于光催化活性的大幅度提高。     

Visible light photocatalytic performance of hierarchical BiOBr microspheres synthesized via a reactable ionic liquid

Hierarchical BiOBr microspheres were synthesized via a one-pot solvothermal process in the presence of ethylene glycol and 1-butyl-3-methylimidazolium bromide ([BMIM]Br) as a reactable ionic liquid. The products were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance absorption spectra, nitrogen adsorption–desorption measurements, and photoluminescence spectroscopy. The photocatalytic activity of BiOBr microspheres was evaluated in terms of the degradation of Rhodamine B (RhB), methyl orange (MO), and 4-chlorophenol (4-CP) under visible light irradiation. We found that the solvothermal temperature had important effects on the crystallinity, crystallite size, optical property, adsorptive performance, and photocatalytic activity of BiOBr microspheres. BiOBr microspheres with a specific surface area of 15.7 m² g⁻¹ prepared at 160 °C exhibited the best adsorption and photocatalytic performance for RhB degradation in aqueous solution. However, this sample showed hardly any activity for photodegradation of 4-CP. Tests using radical scavengers confirmed that h⁺ and O₂⁻ were the main reactive species during RhB degradation. A possible mechanism for photocatalysis by BiOBr microspheres is proposed.     

BiOBr/BiOI-FACs催化剂的组装与光催化性能

以Bi(NO3)3·5H2O、KBr和KI为原料,以粉煤灰漂珠(FACs)为载体,通过中和水解制备了BiOBr/BiOI-FACs复合光催化剂.以50 W蓝光灯为光源,罗丹明B为目标物,考察了制备过程的pH值、保温处理温度和保温处理时间对可见光光催化性能的影响.结果表明,BiOBr/BiOI-FACs复合光催化剂的最佳组装条件为:pH值8.0,保温处理温度160℃,保温处理时间12 h.     

Rapid,simple and low-cost fabrication of BiOBr ultrathin nanocrystals with enhanced visible light photocatalytic activity

BiOBr ultrathin nanocrystals were prepared by a rapid, simple and low-cost route, and characterised by X-ray diffraction, scanning electron microscope, transmission electron microscopy, energy dispersive X-ray, UV–vis diffuse reflectance spectroscopy and electrochemical impedance spectroscopy analyses. The size of the resulting BiOBr ultrathin nanocrystals is about 60–100 nm in width and 15–20 nm in thickness. The photocatalytic activity of the samples was evaluated in terms of the degradation of RhB. Compared with BiOBr three-dimensional microspheres and P₂₅-TiO₂, the BiOBr ultrathin nanocrystals exhibited the best visible-light-induced photocatalytic activity.     

Construction of novel PTh-BiOBr composite with enhanced photocatalytic degradation of Bisphenol A

The high recombination rates of photogenerated electron-holes significant inhibit the catalytic activity of semiconductor photocatalysts. In this study, novel polythiophene (PTh)/BiOBr hybrids were successfully synthesized using an effortless method to achieve the degradation of Bisphenol A (BPA). According to the results, the introduction of polythiophene (PTh) significantly improved the separation efficiency of photocharge carriers, thus enhancing the photocatalytic activity of PTh-BiOBr. The X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectrometer were applied to characterize the samples structure and light absorption properties. The degradation properties of BPA of materials under visible light prove that the photocatalytic capabilities of the complex can be improved significantly compared to BiOBr monomers, thus confirming the above-mentioned hypothesis. Under the same experimental conditions, 0.5% PTh-BiOBr was obtained for the optimal compound, and the degradation efficiency of BPA after 100 min of visible light was 83%, which is 34% higher than that of the BiOBr monomer. In the process of photocatalytic degradation of BPA by the catalyst, the active free radicals of the catalyst were obtained by ESR and free radical capture experiment, while a possible photocatalytic degradation mechanism was proposed on this basis. From O₂, the ?O₂^– plays a major role in the process of photo-react degradation of BPA, while h⁺ and ?OH play a part. This work provides a more eco-friendly and efficient way for BiOBr retouching.     

可循环利用BiOBr/石墨烯水凝胶复合材料的制备及其对丁基钠黄药的降解性能

本文利用水热法合成BiOBr/石墨烯(BiOBr/RGO)水凝胶复合材料,采用XRD、SEM等手段表征复合材料的组成、形貌特征,并探究了BiOBr/RGO水凝胶复合材料对正丁基钠黄药的降解性能。结果表明,成功制备出有利于回收利用的三维宏观BiOBr/RGO水凝胶复合材料;50 mL浓度为25 mg/L的正丁基钠黄药溶液,降解时间为85 min时,10 mg BiOBr/RGO水凝胶复合材料(BiOBr质量分数为92wt%)对黄药的降解率可达96.69%,而纯BiOBr降解率仅为44.84%。总之,RGO的引入可以提升BiOBr的光催化性能,且宏观材料有利于回收再利用。