New photocatalyst BiOCl/BiOI composites with highly enhanced visible light photocatalytic performances

BiOCl/BiOI composites with a visible light response were prepared by a simple hydrothermal method. Even though both single BiOCl and BiOI show low photocatalytic activity, BiOCl/BiOI composites provide enhanced efficiency in decomposing organic compounds including Methyl Orange (MO) and Rhodamine B (RhB). Furthermore, the 20%BiOCl/BiOI composite shows the highest efficiency for decomposing MO, while the highest performance is observed for the degradation of RhB over 70%BiOCl/BiOI composite. A possible photocatalytic mechanism has been proposed based on the relative experiments and the band positions of BiOCl and BiOI.     

BiOCl/UiO‐66 composite with enhanced performance for photo‐assisted degradation of dye from water

Semiconductor‐based photocatalysis is an environmental friendly and cost‐effective technique for water treatment. Due to their unique properties, metal–organic frameworks (MOFs) are considered as ideal platform to develop composite photocatalyst. In this study, Bismuth oxychloride (BiOCl) was first attempt to be incorporated with highly stable MOFs, UiO‐66(Zr) by hydrothermal reaction. Different characterization methods including X‐ray diffraction, Scanning electron microscopy, Fourier transform infrared spectroscope, X‐ray photoelectron spectroscopy had been used to prove the successful synthesis of composite photocatalyst. The resultant BiOCl/UiO‐66 composite showed higher photodegradation performance of Rhodamine B (RhB) under ultraviolet and visible light irradiation than that of pristine materials and their mechanically mixed sample. In addition, the composite exhibited good structural stability and reusability. The photocatalytic mechanism of RhB degradation over the composite under visible light proceeded via a photosensitization process. A better adsorptivity of RhB and effective electron transfer within the hybrid material might be responsible for the enhanced photocatalytic performance.     

MOF-808/BiOCl复合材料的制备及其光催化性能

将高稳定性的MOF-808与BiOCl结合,采用简便的水热法制备出新型MOF-808/BiOCl复合异质结材料。以环丙沙星(CIP)为污染物,探究复合材料MOF-808/BiOCl对CIP的光催化性能。发现含有10% MOF-808的复合材料(MOF-808/BiOCl-10%)表现出最佳的光催化活性。在紫外光照射20 min内,MOF-808/BiOCl-10%对CIP的光催化降解效率高达94.7%。通过X射线粉末衍射、扫描电镜、红外光谱、荧光光谱、紫外可见漫反射光谱、光电流、电化学阻抗等表征技术来考察材料的物相组成、形貌以及光电化学性质。紫外可见漫反射光谱的结果表明,MOF-808/BiOCl-10%材料光吸收范围得到提高。同时进行了自由基捕获实验。基于以上实验数据,提出了MOF-808/BiOCl复合材料可能的光催化机理。     

Oxygen vacancies on the BiOCl surface promoted photocatalytic complete NO oxidation via superoxide radicals

One of the core issues in the photocatalytic oxidation of nitric oxide is the effective conversion of NO into the final product (nitrate). More than just improving the visible light photocatalytic performance of BiOCl, we aim to inhibit the generation of toxic by-product NO₂ during this process. In this study, we demonstrate that the oxygen vacancies (OVs) modulate its surface photogenerated carrier transfer to inflect the NO conversion pathway by a facile mixed solvent method to induce OVs on the surface of BiOCl. The photocatalytic NO removal efficiency under visible light increased from 5.6% to 36.4%. In addition, the production rate of NO₂ is effectively controlled. The effects of OVs on the generation of reactive oxygen species, electronic transfer, optical properties, and photocatalytic NO oxidation are investigated by combining density functional theory (DFT) theoretical calculations, the in situ FTIR spectra and experimental characterization. The OVs on the surface of BiOCl speed the trapping and transfer of localized electrons to activate the O₂, producing O₂⁻, which avoid NO₂ formation, resulting in complete oxidation of NO (NO + O₂⁻ → NO₃⁻). These findings can serve as the basis for controlling and blocking the generation of highly toxic intermediates through regulating the reactive species during the NO oxidation. It also can help us to understand the role of OV on the BiOCl surface and application of photocatalytic technology for safe air purification.     

具有主导晶面的BiOIO3/BiOCl异质结制备与光催化性能

分别以乙二醇/去离子水为溶剂,通过溶剂热/水热法分别制备了具有不同主导晶面的BiOIO₃/{110}BiOCl和BiOIO₃/{001}BiOCl异质结。采用X射线衍射、扫描电子显微镜、能量色散谱和紫外可见漫反射光谱对制备的BiOIO₃/BiOCl光催化剂进行了表征。在可见光照射下,通过对罗丹明 B和苯酚水溶液的光催化降解,考察了 BiOIO₃/BiOCl异质结的光催化活性。结果显示25% BiOIO₃/{110}BiOCl异质结具有最高的光催化效率。BiOIO₃/{110}BiOCl较好的光催化性能是由于其在可见光区较强的光吸收,以及异质结结构和BiOCl所具有的(110)主导晶面有利于光生载流子的分离。超氧自由基(·O₂^-)和空穴(h⁺)是光催化过程中的主要活性物质。此外,根据实验结果探讨了光催化性能增强的机理。     

Ag/BiOX (X=Cl,Br, I)复合光催化剂的制备、表征及其光催化性能

采用光化学沉积法制备了一系列不同Ag含量的新型Ag/BiOX(X=Cl,Br,I)复合光催化剂,应用X射线粉末衍射(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)、光致发光(PL)谱、紫外-可见(UV-Vis)光谱和N2物理吸附等手段对催化剂进行表征,并以420nm<λ<660nm的可见光为光源,评价了该催化剂光催化降解酸性橙II的活性,考察了不同含量的Ag沉积对BiOX样品光催化性能的影响.N2物理吸附测试结果表明,沉积银在一定程度降低了催化剂的比表面积.UV-Vis测试结果表明,Ag能产生表面等离子共振吸收,有效增强BiOCl和BiOBr对可见光的吸收能力.PL测试结果则表明,Ag能显著抑制光生电子(e-)和空穴(h+)的复合.Ag的存在大幅度提高了BiOX对染料的光催化降解活性.当负载Ag的质量分数(w)为1%-2%时,可使BiOCl、BiOBr和BiOI光催化活性分别提高了10、13和2倍.Ag/BiOX复合光催化剂具有更高催化活性的原因是复合光催化剂对可见光有很强的吸收能力,同时产生了银等离子体光催化作用和银抑制了Ag/BiOX(X=Cl,Br,I)的光生电子-空穴的复合.     

Black BiOCl with disorder surface structure prepared by Fe reduction and the enhanced photocatalytic activity

Black bismuth oxychloride (BiOCl) with disordered surface structure has been prepared by a facile Fe reduction method and successfully used as a visible-light photocatalyst. XRD and FESEM results showed that black BiOCl has pure BiOCl phase with plate-like structure. The as-prepared black sample exhibited a broad absorption covered the whole visible light region. The high-resolution TEM images revealed the disordered surface structure, which could be the reason for the black color of BiOCl. The disordered surface was not only responsible for the visible-light absorption but also played a vital role in improving the separation of photo-induced electrons and holes. Methyl orange (MO) photocatalytic degradation experiments showed that the black sample exhibited higher photocatalytic activity than the pristine BiOCl under visible light irradiation. A possible formation mechanism of black BiOCl under Fe reduction was also proposed in our research work.     

具有主导晶面的BiOIO3/BiOCl异质结制备与光催化性能

分别以乙二醇/去离子水为溶剂,通过溶剂热/水热法分别制备了具有不同主导晶面的BiOIO₃/{110}BiOCl和BiOIO₃/{001}BiOCl异质结。采用X射线衍射、扫描电子显微镜、能量色散谱和紫外可见漫反射光谱对制备的BiOIO₃/BiOCl光催化剂进行了表征。在可见光照射下,通过对罗丹明B和苯酚水溶液的光催化降解,考察了BiOIO₃/BiOCl异质结的光催化活性。结果显示25%BiOIO₃/{110}BiOCl异质结具有最高的光催化效率。BiOIO₃/{110}BiOCl较好的光催化性能是由于其在可见光区较强的光吸收,以及异质结结构和BiOCl所具有的(110)主导晶面有利于光生载流子的分离。超氧自由基(·O₂^-)和空穴(h⁺)是光催化过程中的主要活性物质。此外,根据实验结果探讨了光催化性能增强的机理。     

Preparation and measurement of properties of BiOBr/BiOCl/PANI ternary nanocomposite for highly efficient visible light photocatalytic applications

In this paper, we report the synthesis of the BiOBr/BiOCl/PANI ternary nanocomposite using a simple co-precipitation method. The modified photocatalyst produced was characterized by the FT-IR, FE-SEM equipped with EDS (as a Map), TEM, XRD, PL, Raman, and UV–Vis DRS analytical techniques. The synergetic effect of PANI and surface defects in nanoplates can prolong the recombination rate of photo-generated charge carriers. Thus, photocatalytic and photoelectrochemical activities of samples have been studied. Then, the methyl orange (MO) degradation performance of PANI/BiOBr and BiOBr/BiOCl/PANI was investigated under visible light irradiation. The lamp used to simulate sunlight in this photocatalytic study process was power down white light (5-W LED), less reported. The results got exhibited that the as-prepared BiOBr/BiOCl/PANI (90:10, Bi:PANI) nanocomposite showed a higher photocatalytic efficiency. Based on the scavenger tests, ^·O₂^? played a significant role in the degradation of MO. The connection between BiOBr, BiOCl, and PANI improved photocatalytic activity, which enhanced migration rate of the photo-generated electrons besides limiting the recombination of photo-generated electron–hole pairs.

     

WO3/BiOCl, a novel heterojunction as visible light photocatalyst

A bismuth oxychloride (BiOCl) nanostructure is prepared by a new low temperature route using sodium dodecyl sulfate as template and urea as hydrolytic agent. A novel heterojunction is developed between BiOCl and tungsten oxide (WO(3)) to make it an efficient visible light photocatalyst. The catalysts were characterized by X-ray diffraction analysis, Raman spectroscopy, thermogravimetric analysis, energy-dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, and N(2) sorption isotherms. The WO(3)/BiOCl heterojunction system extends the absorption edge to the visible region efficiently. BiOCl works as a main photocatalyst while WO(3) acts as the photosensitizer absorbing visible light in the WO(3)/BiOCl composite. The individual BiOCl and WO(3) show very low photocatalytic efficiency under visible light irradiation but their heterojunction provides unexpectedly high efficiency in decomposing rhodamine B as compared to Degussa P25, pure BiOCl, and WO(3).     

Room Temperature Synthesis and Photocatalytic Activity of Magnetically Recoverable Fe3O4/BiOCl Nanocomposite Photocatalysts

Magnetically recoverable Fe₃O₄/BiOCl nanocomposite photocatalysts were fabricated by a simple chemical coprecipitation method at room temperature. The amount of Fe₃O₄ incorporated into BiOCl was varied from 0 to 20 wt%. The as-synthesized samples were characterized by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, UV–Vis diffuse reflectance spectroscopy, and vibrating sample magnetometer. The obtained results show that the as-synthesized samples mainly contain both crystalline phases (Fe₃O₄ and BiOCl) and are composed of flower-like nanostructures. Compared to UV light-responsive BiOCl, all the nanocomposite photocatalysts show a strong light absorbance in the range of 250–800 nm, demonstrating that the Fe₃O₄/BiOCl nanocomposites can respond to visible as well as UV light. Moreover, visible light absorbance was increased with the increase in the Fe₃O₄ amount in the composite. The photocatalytic activity of nanocomposite photocatalysts was evaluated by the photodegradation of Rhodamine B (RhB) over the samples under visible light irradiation. The 10 wt% Fe₃O₄/BiOCl nanocomposite photocatalyst shows the highest photocatalytic efficiency among the samples. The Fe₃O₄/BiOCl nanocomposite photocatalyst was stable under visible light irradiation to efficiently degrade RhB molecules after five cycles and could be easily recovered with a magnet after each cycle.     

Fabrication of FeOOH/BiOCl Nanocomposites with Enhanced Visible Light Photocatalytic Activity

BiOCl as a two‐dimensional layer ternary oxide semiconductor, has been widely used in energy and environmental area due to its non‐toxicity, price and the good photocatalytic performance. However, BiOCl has a wide bandgap and can only absorb ultraviolet light, which limits its solar energy conversion efficiency for practical application. Herein, we report a facile synthesis of FeOOH/BiOCl nanocomposites by hydrothermal method. The results of XPS and FT‐IR indicated that FeOOH has been loaded on the nanocomposites. The chemical and optical properties of the nanocomposite are well‐characterized. The nanocomposite showed much more excellent photocatalytic performance compared with the individual FeOOH and BiOCl single component. Reactive specie trapping experiment indicated that · O^2– and h⁺ were the two main active species during the photocatalytic process of FeOOH/BiOCl nanocomposites.     

盐酸溶液处理钒酸铋增强可见光催化活性及其机理

采用盐酸水溶液处理BiVO₄ 的方法获得增强的光催化活性. 在0.1 mol·L^-1 酸溶液中浸渍反应6 h,BiVO₄ 的可见光催化降解苯酚的活性提高了3.5 倍. 采用X 射线衍射(XRD), 扫描电镜(TEM)和漫反射光谱(DRS)等表征手段研究处理后样品的晶相组成和表面形貌, 结合不同酸和氯化物处理的对照实验, 结果表明,在H⁺和Cl^-的协同作用下, BiVO₄表面部分溶出并以BiOCl 沉积, 形成了表面具有凹陷沟壑的BiVO₄颗粒与片状结构BiOCl 的复合物. 采用悬浮液光电压法测定BiOCl 平带电位, 通过BiVO₄和BiOCl 的能带分析及其混合颗粒的光催化活性测试, 确证二者间不存在颗粒间电子转移效应. 增强的光催化活性主要归因于BiVO₄表面形成了有助于光生电荷迁移的凹凸不平结构. 这种表面处理方法有望成为一种增强半导体化合物光催化活性的有效途径.     

氯氧化铋催化剂的电子结构调控及其光催化性能研究

以不同Bi/Cl摩尔比例为原料设计合成了一系列BiOCl半导体催化材料。扫描电子显微镜、XRD衍射峰拟合等分析结果显示,Bi/Cl比例的改变对BiOCl的形貌、表面结构、微观电子结构均具有一定的调控作用。以Bi/Cl = 1 : 1为原料合成的BiOCl光催化剂具有最窄的带隙值（Eg=3.18 eV）,使得其具有较强的的光响应能力。光催化去除罗丹明B（RhB）结果表明,随着Bi/Cl摩尔比例的减小,BiOCl的催化性能呈现先增强后减弱的趋势。Bi/Cl = 1 : 1样品具有最优的催化活性,源于其较优异的光吸收性能以及特殊的表面特性。光催化机理研究表明,光催化去除RhB的过程中,起作用的活性物质主要为光生电子、空穴以及半导体表面产生的超氧自由基。     

BiOCl/In2S3复合可见光催化剂制备及性能研究

氯氧化铋（BiOCl）较大的禁带宽度使得其只能对紫外光产生响应,严重制约了其进一步光催化应用。为实现BiOCl对可见光的利用,以In2S3为可见光光敏剂,并基于高效实用的机械研磨手段构建BiOCl/In2S3复合可见光催化剂。通过扫描电子显微镜(SEM)、X射线衍射(EDS)、X射线衍射(XRD)、红外光谱(FT-IR)和紫外-可见漫反射光谱(UV-Vis DRS)等方法对催化剂的形貌和结构进行表征。选择盐酸四环素（TC）可见光催化降解为评价模型,系统研究了BiOCl/In2S3复合比例对光催化活性的影响。结果表明两者复合比例为1:1时具有最佳的光催化活性,在可见光照射下对TC的降解效率高达91.4%,且经3次循环降解效率仍保持在87.3%。机理研究表明,In2S3被可见光激发产生电子注入BiOCl的导带(CB),能有效提升载流子的分离效率,而h+和?O2-是光降解过程中的主要活性物质。该项研究工作充分表明了In2S3对BiOCl的高效光敏活性,展示了物理复合法在新型高效可见光催化体系构建中的重要意义。     

Synthesis,properties and mechanism of photodegradation of core–shell structured upconversion luminescent NaYF4:Yb3+,Er3+@BiOCl

Microspherical bismuth oxychloride (BiOCl) can only utilize ultraviolet (UV) light to promote photocatalytic reactions. To overcome this limitation, a uniform and thin BiOCl nanosheet was synthesized with a particle size of about 200 nm. As results of UV–visible diffuse reflectance spectroscopy showed, the band gap of this nanostructure was reduced to 2.78 eV, indicating that the BiOCl nanosheet could absorb and utilize visible light. Furthermore, the upconversion material NaYF₄ doped with rare earth ions Yb³⁺ and Er³⁺ emitted visible light at 410 nm following excitation with near‐infrared (NIR) light (980 nm), which could be utilized by BiOCl to produce a photocatalytic reaction. To produce a high‐efficiency photocatalyst (NaYF₄:Yb³⁺,Er³⁺@BiOCl), BiOCl‐loaded NaYF₄:Yb³⁺,Er³⁺ was successfully synthesized via a simple two‐step hydrothermal method. The as‐synthesized material was confirmed using X‐ray diffraction, scanning electron microscopy, X‐ray photoelectron spectroscopy as well as other characterizations. The removal ratio of methylene blue by NaYF₄:Yb³⁺,Er³⁺@BiOCl was much higher than that of BiOCl alone. Recycling experiments verified the stability of NaYF₄:Yb³⁺,Er³⁺@BiOCl, which demonstrated excellent adsorption, strong visible‐light absorption and high electron–hole separation efficiency. Such properties are expected to be useful in practical applications, and a further understanding of the NIR‐light‐responsive photocatalytic mechanism of this new catalytic material would be conducive to improving its structural design and function.     

源于铋玻璃的富氧空位BiOCl光催化材料的原位合成及性能

氧空位对光催化材料的可见光吸收范围与电子-空穴分离效率都具有重要影响,铋玻璃内含有丰富的氧空位缺陷.采用盐酸腐蚀铋玻璃原位合成BiOCl光催化材料,研究了玻璃网络外体对氧空位浓度的影响规律,并利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)以及电子顺磁共振(EPR)对合成的BiOCl材料的结...     

Increasing visible-light absorption for photocatalysis with black BiOCl

Black BiOCl with oxygen vacancies was prepared by UV light irradiation with Ar blowing. The as-prepared black BiOCl sample showed 20 times higher visible light photocatalytic activity than white BiOCl for RhB degradation. The trapping experiment showed that the superoxide radical (O(2)(?-)) and holes (h(+)) were the main active species in aqueous solution under visible light irradiation.     

超声波辐射快速合成高光催化性能的BiOCl(Br)纳米片

在室温条件下,利用超声波辐射方法快速合成了四方状BiOCl(BiOBr)纳米片光催化剂。应用N2-物理吸附、X射线粉末衍射、扫描电镜、透射电镜、紫外可见光谱等手段对催化剂进行了表征,并以波长为λ=365 nm的紫外光和420 nm<λ<660 nm的可见光为光源,评价了该催化剂光催化降解酸性橙Ⅱ的活性。表征结果表明,超声波辐射可加速BiOCl和BiOBr晶化过程,显著提高BiOCl和BiOBr的结晶度,并使其晶粒发生细化,提高催化剂的比表面积。活性测试表明,声化学合成样品的光催化活性优于普通搅拌制备的样品。其中BiOCl的紫外光催化活性高于商业TiO2(P25)光催化剂。     

Construction of immobilized films photocatalysts with CdS clusters decorated by metal Cd and BiOCl for photocatalytic degradation of tetracycline antibiotics

A kind of CdS/Cd-BiOCl immobilized films photocatalyst was prepared. The optical and physicochemical properties of the CdS/Cd-BiOCl photocatalysts were analysed, and the detailed characterization revealed CdS/Cd-BiOCl films photocatalyst with good charge carrier separation effect. The reusabilities and photocatalytic properties of the samples were studied. The 15%CdS/Cd-BiOCl photocatalyst exhibited superior performance in photocatalytic degradation of tetracycline (TC) and favorable stability under visible light irradiation. As for the photodegradation rate of TC, 15%CdS/Cd-BiOCl exhibited an excellent photodegradation activity, which is 4.06 and 9.53 times higher than that of CdS/Cd and BiOCl, respectively. The results showed that dominant active species are ^?O₂^? and ^?OH radicals during photodegradation. The charge transfer in Z-scheme CdS/Cd-BiOCl films photocatalyst could synchronously generate conduct band (CB) electrons in BiOCl and valence band (VB) holes in CdS, and metal Cd served as electron mediator. This work can be a reference for the design of film photocatalysts and new insight for photodegradating towards contaminants.