类水滑石催化合成聚(碳酸1,4-丁二醇)酯二醇

采用共沉淀法制备了镁铝类水滑石(Mg-Al-CO3LDH)、镁锌铝类水滑石(Mg-Zn-Al-CO3LDH)和锌铝类水滑石(Zn-Al-CO3LDH),并研究了它们在碳酸二苯酯(DPC)与1,4-丁二醇(1,4-BD)酯交换合成聚碳酸酯二醇(PCDL)反应中的催化活性。在常压反应阶段,以苯酚的产率表征催化剂的活性;在减压缩聚阶段,以产品的数均分子量Mn和羟基值来表征催化剂的活性。结果发现,Zn-Al LDH具有良好的催化活性。在优化反应条件下,获得了Mn和羟基值分别为1600和70.8mg KOH/g的PCDL。     

纳米晶镁铝水滑石的制备及其热分解机理

研究了无机阻燃剂镁铝水滑石纳米晶的制备及其热分解机理.采用常压下,一步反应的液相法制备镁铝水滑石试样，用XRD和TEM测试试样的相组成和形貌，针状镁铝水滑石纳米晶体的长度约80 nm.依据DSC和DTA-TG测试结果，发现镁铝水滑石纳米晶的热分解由两个阶段组成:第一个吸热峰出现在220 ℃左右，第二个吸热峰出现在380 ℃左右.研究了反应时间对所得镁铝水滑石试样的热分解性能的影响，发现延长反应时间，镁铝水滑石试样的第一次、第二次热分解的起始温度升高,第一次热分解的失重值增大，最后剩余氧化物的量增大，从而增强镁铝水滑石阻燃剂的阻燃性能.根据不同升温速率下获得的DSC测试数据，应用Achar微分法、Šatava-Šesták积分法和Ozawa积分法对镁铝水滑石纳米晶热分解的第二个阶段进行了动力学计算和分析，确定该段的热分解机理函数积分式为(1－α)－1－1.     

镁铝水滑石负载MnO-4催化氧化乙苯合成苯乙酮

采用焙烧还原法制备了镁铝水滑石负载MnO4-催化剂,并将其应用于催化氧气氧化乙苯合成苯乙酮的反应中。考察了催化剂用量、反应温度、反应时间、MnO4-负载量和镁铝比等因素对催化氧化反应的影响及催化剂的重复使用性能。在优化条件下:催化剂用量3 g,乙苯用量45 mL,反应温度120℃,水滑石结构中n(Mg)/n(Al)=5,氧气流量100 mL/min,苯乙酮产率可达57.0%,苯乙酮选择性可达96.3%,催化剂重复使用3次催化活性降低较小。     

负载锑的水滑石催化环己酮Baeyer-Villiger氧化制ε-己内酯

 通过浸渍法制备了负载Sb的镁铝水滑石类化合物Sb/HT, 用X射线衍射(XRD)和热重(TG)等技术对催化剂的结构进行了表征,研究了其对环己酮Baeyer-Villiger(BV)氧化制ε-己内酯的催化性能,考察了催化剂制备条件和反应条件对催化活性的影响以及催化剂的再生性能. 结果表明,在乙腈作为溶剂的体系中,负载Sb的镁铝水滑石对环己酮氧化制ε-己内酯具有较高的催化活性. 在水滑石前驱体中镁/铝摩尔比为3, Sb含量为1.5%和焙烧温度为450 ℃时制备的Sb/HT催化剂的催化活性最高,在10 ml乙腈和140 mmol 30%H2O2中于70 ℃反应4 h后,环己酮的转化率达42%,ε-己内酯选择性达94%. 催化剂可多次再生重复使用,催化活性稳定.     

La(OH)3负载锌铝水滑石的制备及其应用在锌镍二次电池中的性能

采用共沉淀法将氢氧化镧(La(OH)₃)负载在锌铝水滑石(Zn-Al LDHs)的表面,扫描电镜(SEM)、X射线衍射(XRD)表明La(OH)₃成功负载在锌铝水滑石表面,并且负载后的锌铝水滑石仍然为六边形片状晶体,且粒径均匀、分散性好。La(OH)₃质量其具有较好的可逆性、更大的正腐蚀电位及较小的电池内阻。5%La(OH)₃@Zn-Al LDHs在经过80次循环后,其循环保持率为94.84%。     

高荧光性含锌类水滑石研究

本研究将适量锌离子(II)取代镁铝水滑石中的镁离子(II), 以及将一定量的8-羟基喹啉(8-hydroxyquinoline)分散于镁铝水滑石层间的亲油性阴离子中, 使与其板层表面上的锌离子配位, 经共沉淀法, 合成、组装得到一类迄今未见报道的具高荧光性的类水滑石(Zn-HTLC)荧光材料. 采用荧光光谱、红外光谱、紫外光谱、X射线衍射和热分析等对其进行了表征. 研究表明, 这种类水滑石在紫外光下可发出强烈的蓝绿色荧光(501 nm), 荧光强度高达4.5×10⁵ a.u., 说明锌离子(II)分散于类水滑石的氢氧化镁板层中, 可有效防止发光结构单元的荧光猝灭, 而且溶于层间阴离子中的配体与板层上的锌离子(II)配位所形成的特殊组装结构, 增强了发光中心的不对称性, 也是其具有高荧光性的可能原因. 热分析结果显示, 这种类水滑石耐热性强, 有望应用于各种功能性荧光材料.     

镁铝类水滑石的合成、表征及其催化丙酮缩合性能

采用共沉淀-水热法合成了一系列的类水滑石样品.用XRD、TEM等表征了合成样品的结构及表面形貌;用NH3-TPD、CO2-TPD测试样品表面酸碱性质,优化了镁铝水滑石的合成条件,重点考察了镁铝比对合成样品晶形的影响和样品表面酸碱性变化的规律,阐述了层板上原子配位分布的微观结构,以及不同镁铝比的类水滑石在催化丙酮缩合制备双丙酮醇反应中催化性能.     

磷钨酸插层Zn/Al类水滑石催化合成邻苯二甲酸二(2-乙基)己酯

以对苯二甲酸根阴离子为预支撑体,制备了磷钨酸插层Zn/Al类水滑石杂化物催化剂,将其用于邻苯二甲酸二(2-乙基)己酯(DOP)的合成反应.研究了原料配比、催化剂用量、反应温度、反应时间等对邻苯二甲酸酐转化率的影响,及催化剂的可重复利用性.结果表明,磷钨酸-Zn/Al类水滑石杂化催化剂对DOP合成的催化效果较好,在催化剂用量为苯酐质量的0.76%,异辛醇与邻苯二甲酸酐的摩尔比为2.5,反应温度为180℃,反应时间为4.5 h,带水剂环己烷约为苯酐质量65%的反应条件下,苯酐转化率可达92.8%;反应10 h转化率可达97.9%.催化剂重复使用时转化率略有下降,经过乙醇洗涤再生,活性即可基本恢复.     

反气相色谱法测定锌镁铝类水滑石的表面性能

采用水热合成法制备了锌镁铝类水滑石(ZnMgAl-HTLC),利用X射线衍射仪(XRD)对ZnMgAl-HTLC的晶体结构进行了表征,并以一系列非极性和极性分子为探针分子,采用反气相色谱法(IGC)研究了ZnMgAl-HTLC的表面性能.结果表明:XRD特征衍射峰窄、尖、高,水热合成法能够制得纯度较高的ZnMgAl-HTLC; ZnMgAl-HTLC表面吸附自由能小于零,表面色散自由能最大为6.02 mJ/m²,酸碱作用自由能最大为5.33 kJ/mol,吸附焓为43.6 kJ/mol,吸附熵为0.15 kJ/mol.本文的反气相色谱方法对研究锌镁铝类水滑石的表面性能具有重要的指导意义.     

SDBS/水滑石组装合成与结构表征研究

采用共沉淀法制备镁铝水滑石以及十二烷基苯磺酸钠(SDBS)插层水滑石,应用XRD、FT-IR、TG-DTA等手段表征合成水滑石的结构。实验研究表明:得到的镁铝水滑石(Mg-Al-NO₃-LDHs)以及十二烷基苯磺酸钠插层水滑石(SDBS-LDHs)很好地保持了水滑石的层状结构,结构完整,晶相单一。研究表明共沉淀法可以成功地把十二烷基苯磺酸钠插入层状氢氧化镁铝层间,并使用分子动力学模拟方法模拟了插层复合物的微观结构,通过模拟得到的结果与实验测试结果接近。     

Sunlight-Active BiOI Photocatalyst as an Efficient Adsorbent for the Removal of Organic Dyes and Antibiotics from Aqueous Solutions

A bismuth oxyiodide (BiOI) photocatalyst with excellent sunlight-driven performance was synthesized by a solvothermal route without the addition of surfactants or capping agents. The prepared photocatalyst exhibited a tetragonal phase with an energy band gap of 2.15 eV. The efficiency of the photocatalyst was elucidated by monitoring the photodegradation of organic dyes and antibiotics. The BiOI photocatalyst provided a 95% removal of norfloxacin (NOR) antibiotics under visible light illumination. Interestingly, the complete removal of Rhodamine B (RhB) dye was achieved after 80 min of natural sunlight irradiation. The photodegradation reaction followed the first-order reaction. Both photo-generated holes and electrons play vital roles in the photodegradation of the pollutant. The BiOI photocatalyst remains stable and still shows a high efficiency even after the fifth run. This confirms the great cycling ability and high structural stability of the photocatalyst. The prepared BiOI catalyst, with a high surface area of 118 m² g⁻¹, can act as an excellent adsorbent as well. The synergistic effect based on both adsorption and photocatalysis is a key factor in achieving a very high removal efficiency. The photoactivity under sunlight is higher than that observed under visible light, supporting the practical use of the BiOI photocatalyst for the removal of organic pollutants in wastewater through the utilization of abundant solar energy.     

Fabrication of PET/BiOI/SnO2 heterostructure nanocomposites for enhanced visible-light photocatalytic activity

Heterojunction BiOI/SnO₂ nanocomposites have been facilely synthesized by using successive ionic layer adsorption and reaction (SILAR) and a hydrothermal method, and polyethylene terephthalate (PET) nanofibers (NFs) were utilized as a photocatalyst carrier to support the BiOI/SnO₂ nanocomposites. PET/BiOI/SnO₂ NFs displayed excellent photocatalytic ability towards methyl orange (MO) and tetracycline (TC) under visible light irradiation. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were employed to investigate the morphology, crystal structure and chemical state of the PET/BiOI/SnO₂ nanofibers. Photoluminescence (PL) and active species trapping experiments indicated that photoinduced charge separation promoted the formation of holes (h⁺) and superoxide radicals (•O²_-). Moreover, a photodegradation mechanism was proposed to illustrate that the formation of a Fermi level equilibrium state between semiconductors accelerated charge separation in the semiconductor. This study is meaningful for providing new inspiration to design and fabricate novel heterostructure photocatalysts with enhanced photocatalytic activity.     

Graphene/BiOI composites synthesized via the oil bath method and their application for efficient photocatalytic degradation of methyl orange under visible light irradiation

An efficient and simple oil bath method for rapid synthesis of graphene/BiOI as visible light active photocatalyst was described. The resultant graphene/BiOI composites were characterized by different techniques, including scanning electron microscopy, X-ray diffraction, and ultraviolet-visible diffuse reflectance spectroscopy. The photocatalytic activity of the as-prepared graphene/BiOI composites for methyl orange degradation was also investigated under visible light irradiation. The results show that BiOI and graphene taken with a mass ratio of 100: 1 exhibited the highest photocatalytic efficiency, which is two times that of pure BiOI. Part of this effect results from higher specific surface area that provides an increased number of active sites. A relatively narrow band gap (2.08 eV) formed in the heterostructure can also contribute to this effect. A suggestion of the photocatalytic mechanism was also offered.     

Reduced-graphene-oxide-wrapped BiOI-AgI heterostructured nanocomposite as a high-performance photocatalyst for dye degradation under solar light irradiation

Solar photocatalytic water treatment has emerged as a promising way to provide clean water. However, most traditional photocatalysts (TiO₂, ZnO, etc.) are active only under ultraviolet light and have high recombination rates of photoinduced electron-hole pairs; therefore, they are not sufficient to fulfill all of the demands of practical applications. This problem could be overcome by developing highly solar-light-active and durable heterostructured photocatalysts. In this study, a new solar-light-active heterostructured reduced graphene oxide (RGO)/BiOI/AgI photocatalyst was successfully fabricated through a simple precipitation method. The resultant heterostructured RGO/BiOI/AgI nanocomposite exhibited extraordinary photocatalytic performance in the degradation of rhodamine B (RhB) under simulated sunlight irradiation. The measured rate constant of the RGO/BiOI/AgI nanocomposite was six times higher than that of bare BiOI nanostructures. Its extraordinary capacity for harvesting full-spectrum light and long-term stability makes the RGO/BiOI/AgI nanocomposite a potential photocatalyst for environmental remediation.     

石墨烯量子点修饰的BiOI/PAN柔性纤维的制备及其增强的光催化活性

In environment remediation, photocatalytic oxidation is a promising technique for removing organic pollutants. Compared to adsorption, biodegradation, and chemical oxidation, photocatalytic oxidation can eliminate organic pollutants completely, conveniently, and cheaply in an environmentally friendly manner. Visible-light-driven photocatalytic oxidation is particularly advisable because of the high proportion of visible light energy in solar energy. Bismuth oxyiodide (BiOI) is a promising visible-light-driven photocatalyst for the oxidization of pollutants, not only because of its narrow band gap, but also for its relatively low valence band (VB), which is adequate for photogenerated holes to oxidize a variety of organic compounds. However, the shortcomings of BiOI powder, such the difficulty of recycling it, its low surface area, and fast carrier recombination, limit its practical applications. Meanwhile, the flexibility and hierarchical structure of photocatalysts are particularly advisable because these properties are beneficial for the convenient operation, recycling, and performance improvement of these materials. Herein, based on an electro-spun polyacrylonitrile (PAN) nanofiber substrate, a hierarchical BiOI/PAN fiber was prepared through an in situ reaction. In the as-prepared BiOI/PAN fibers, BiOI flakes were aligned vertically and uniformly around the PAN fibers. BiOI nuclei generated from pre-introduced Bi(Ⅲ) in the PAN fiber act as seeds for the growth of BiOI nanoplates, which is crucial for the formation of a hierarchical structure. Such a hierarchical structure can improve both the light absorption and carrier generation of the BiOI/PAN fibers, as demonstrated by UV-Vis diffuse reflectance spectra and photoluminescence emission. Therefore, the BiOI/PAN fibers exhibited higher photocatalytic activity than BiOI powder. When the BiOI/PAN fibers were decorated with pre-prepared graphene quantum dots (GQDs), a GQD-modified BiOI/PAN fibrous composite (GQD-BiOI/PAN) was fabricated. The morphology of the obtained GQD-BiOI/PAN fibers was nearly the same as that of the BiOI/PAN fibers. A step-scheme (S-scheme) heterojunction was formed between the GQDs and BiOI, which was confirmed by the fabrication method, photoluminescence emission, reactive radical tests, and XPS analysis. This kind of S-scheme heterojunction can not only effectively suppress the recombination of photogenerated holes, but can also reserve the more reductive electrons on the lowest unoccupied molecular orbital of GQDs and the more oxidative holes on the VB of BiOI, for the photocatalytic degradation of phenol. Because of the fibrous hierarchical structure and S-scheme heterojunction, GQD-BiOI/PAN outperformed BiOI nanoparticles and BiOI/PAN nanofibers in the photocatalytic oxidation of phenol under visible light. In addition, because of tight bonding, GQD-BiOI/PAN can be tailored and operated by hand, which is convenient for recycling. During recycling, no obvious loss of sample or decrease in photocatalytic activity was observed. This work provides a new pathway for the fabrication of flexible photocatalysts and a new insight into the enhancement of photocatalysts.      

花球状Bi2S3/BiOI复合光催化剂在空气中净化甲醛的应用

以硫代乙酰胺为硫源,采用水热阴离子转移法,制备由纳米片组装的花球状Bi₂S₃/BiOI复合光催化剂。以气相甲醛作为模型污染物,在检测舱中考察了复合催化剂对甲醛的净化作用。结果表明,具有异质结结构的Bi₂S₃/BiOI复合光催化剂具有较高的光催化活性,能在可见光下净化空气中的甲醛,并且具有良好的循环使用稳定性。     

花球状Bi2S3/BiOI复合光催化剂去除空气中甲醛的应用

以硫代乙酰胺为硫源,采用水热阴离子转移法,制备由纳米片组装的花球状Bi₂S₃/BiOI复合光催化剂。以气相甲醛作为模型污染物,在检测舱中考察了复合催化剂对甲醛的去除作用。结果表明,具有异质结结构的Bi₂S₃/BiOI复合光催化剂具有较高的光催化活性,能在可见光下去除空气中的甲醛,并且具有良好的循环使用稳定性。     

Preparation of Photocatalyst-supported Polyacrylonitrile Micro/Nano Composite Fiber Material and Its Photocatalytic Activity

Acomposite photocatalyst, with branch-like BiOI/Bi₂WO₆ he-terojunction deposited on the polyacrylonitrile micro/nano composite fiber(PAN MNCF), was prepared via two step hydrothermal method. The products are characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), photoluminescence(PL) spectra, UV-Vis diffuse reflection spectroscopy(UV-Vis DRS) and time-resolved fluorescence spectra. The PAN/BiOI/Bi₂WO₆ micro/nano composite fiber(PAN/BiOI/Bi₂WO₆ MNCF) showed better visible-light photocatalytic performance than PAN MNCF or BiOI/Bi₂WO₆ powder, probably ascribed to the collective effect between PAN MNCF and BiOI/Bi₂WO₆ heterojunction. Significantly, the PAN/BiOI/Bi₂WO₆ MNCF could be easily recycled through filtration method, thus avoiding the secondary pollution.     

Synthesis of BiOI photocatalyst by microwave method using EDTA as retarder of the reaction

Research on Chemical Intermediates - BiOI photocatalyst was successfully synthesized following a rapid synthesis by using microwave irradiation and EDTA as retarder of the reaction in aqueous...     

Evaluation of the reaction mechanism for photocatalytic degradation of organic pollutants with MIL-88A/BiOI structure under visible light irradiation

Research on Chemical Intermediates - In this study, we synthesized novel visible light photocatalyst MIL-88A/BiOI using depositing BiOI particles on the surface of a metal–organic framework...