增强光催化活性的3D分级结构Bi2W06微球及表面酸性

以KNO3为矿化剂,用水热法制备了3D分级结构Bi2WO6微球,通过XRD、SEM、BET对产物进行了表征．探讨了3D分级结构Bi2WO6微球可能的形成机理．以罗丹明B为模型污染物,研究了合成产物的光催化性质．结果表明：在紫外光下,RhB的降解以共轭结构断裂的光催化反应为主;而在可见光照射下,RhB的降解可能是光催化和光敏化共同作用的结果．进一步以吡啶为探针分子,通过吸附吡啶红外光谱探讨了Bi2W06表面酸性与光催化降解RhB之间的关系．研究显示,Bi2W06具有较强的表面酸性,增强了Bi2WO6与RhB分子之间吸附作用,有利于染料分子上的电子跃迁至催化剂上,易于发生光敏化和光催化反应。     

花状结构Bi2WO6多孔微球: 组装及光催化性能

利用表面活性剂十六烷基三甲基溴化铵(CTAB)、十二烷基苯磺酸钠(SDBS)作为结构导向剂,在水热条件下合成了由纳米片组装而成的Bi2WO6花状多孔微球的新颖结构。探讨了反应时间、表面活性剂种类等因素对产物形貌、结构和性能的影响。在氙灯照射下,发现使用CTAB所得到的Bi2WO6比添加SDBS所得到的样品具有更高的催化罗丹明B降解的活性,原因是前者具有较大的比表面积和吸收阈值。同时提出了晶体可能的生长机理为各向异性生长特性和自组装-Ostwald熟化过程的结合。     

具有可见光增强芬顿活性的Ⅱ型2D/2D Cu2ZnSnS4/Bi2WO6异质结(英文)

高级氧化工艺(AOPs)是一种处理有机污染物的极具吸引力的技术.大量的前期研究工作集中在通过芬顿反应(Fenton)降解有机污染物.然而,芬顿反应需要在酸性条件下进行,必须在其过程中进行预处理.同时,反应后产生的含铁污泥需要进一步处理以满足排放要求,从而限制了芬顿反应的发展.作为另一种AOPs,光催化技术因反应条件温和、操作简单和选择性好等优点受到广泛关注.研究表明,各种铁基和铜半导体光催化材料形成光-芬顿(Photo-Fenton)系统,可有效解决芬顿反应中高价金属离子/低价金属离子的循环问题.为了充分利用芬顿氧化技术和光催化氧化技术在降解有机污染物方面的各自优势,构建具有宽太阳光谱响应的新型光芬顿催化剂具有重要意义.由于其独特的层状结构和优越的有机物光催化性能, Bi₂WO₆作为结构最为简单的钙钛矿型层状氧化物,其禁带宽度为2.6–2.8 eV,可响应可见光,已成研究最多的光催化材料之一.研究表明,将Bi₂WO₆与合适的助催化剂耦合以构建异质结是提高光生载流子分离效率、拓宽Bi₂     

粉煤灰漂珠负载Bi2WO6复合材料的制备及光催化性能研究

以工业固体废弃物粉煤灰漂珠(fly ash cenospheres,FACs)为载体,采用水热法制备了新颖的漂珠负载Bi2WO6复合材料(Bi2WO6/FACs),通过X射线衍射(XRD),扫描电子显微镜(SEM),X-射线光电子能谱(XPS),和紫外-可见漫反射光谱(DRS)技术对其进行了表征。XRD数据显示了正交相Bi2WO6的特征衍射峰。DRS结果证实了引入FACs后Bi2WO6对可见光的吸收增强。在可见光的照射下,以亚甲基蓝溶液的光催化降解评价了Bi2WO6/FACs复合材料的光催化性能。结果表明:Bi2WO6/FACs的光催化性能优于纯Bi2WO6的,其一级反应速率常数(k)为后者的2.4倍。尤其是由于漂珠质轻中空的特性,Bi2WO6/FACS复合光催化剂可长时间漂浮于水面,既能充分吸收光能,又有利于催化剂的回收和重复利用。     

三维花状Bi2WO6/BiOBr异质结的制备及对多种染料的降解性能

利用水热法以十二烷基二甲基溴化铵(DDAB)和十六烷基三甲基溴化铵(CTAB)为结构导向剂以及溴源,成功地制备了三维花状Bi₂WO₆/BiOBr异质结。通过X射线粉末衍射、扫描电镜、透射电镜、紫外可见漫反射光谱、光电流、Nyquist曲线和电子顺磁共振分别对样品的结构、形貌、组成和光电化学性能进行了表征。结果表明,20~30 nm的BiOBr纳米粒子均匀地附着在Bi₂WO₆薄片上形成三维花状结构。Bi₂WO₆/BiOBr与纯Bi₂WO₆相比,扩展了可见光的响应范围,且提高了催化剂光生电子与空穴的分离效率。光降解实验表明w_DDAB/w_CTAB=2.6时Bi₂WO₆/BiOBr的光催化性能最优。在300 W氙灯(波长>420 nm)可见光照射下,其在降解罗丹明B中表现出最高的反应速率常数(0.0997 min^-1),分别约为Bi₂WO₆(0.0376 min^-1)和BT?4(0.0523 min^-1,w_DDAB/w_CTAB=3.9)的2.7倍和1.9倍,且6个循环后活性依然没有明显衰减。Bi₂WO₆/BiOBr异质结还可以无选择性地降解其他类型的有机染料,如亚甲基蓝、孔雀石绿和甲基橙。最后,基于活性物种捕获实验和Mulliken原子电负性理论计算结果,提出了Bi₂WO₆/BiOBr异质结的光降解机理。     

高级氧化和可见光照射协同作用下Bi2WO6对有机污染物降解的催化活性增强(英文)

随着工业化社会的不断发展,环境问题日益严重。尤其是工业废水问题一直是催化降解领域的研究热点。光催化与高级氧化工艺(AOPs)耦合技术因为具有高效、无选择性、处理条件温和等特点,被认为是一种高效的有机污染物降解技术。本文以十六烷基三甲基溴化铵(CTAB)表面活性剂作为模板,采用简单的水热法制备了钨酸铋(Bi₂WO₆)纳米花。通过X射线衍射(XRD)、傅里叶红外光谱(FTIR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)和紫外-可见漫反射光谱(DRS)技术对其微观形貌、晶相、表面化学元素状态和光学性质进行了表征。为了研究钨酸铋(Bi₂WO₆)纳米花的催化性能,在不同催化体系下降解有机污染物罗丹明B (Rh B),实验发现,于vis/过硫酸盐(PMS)/Bi₂WO₆体系下,40 min内对Rh B的去除率高达96.39%,明显优于PMS/Bi₂WO₆ (40 min内去除率为38.7...     

Br掺杂Bi2WO6微球的制备及其光催化性能

以五水合硝酸铋和二水合钨酸钠为原料,以十六烷基三甲基溴化铵（CTAB）为溴源,制备Br掺杂Bi₂WO₆,通过调节CTAB的含量,利用水热法制备了Br掺杂量不同的Bi₂WO₆催化剂。以抗生素环丙沙星、诺氟沙星作为污染物,测试Br掺杂Bi₂WO₆催化剂的光催化性能。结果表明,2%掺杂量（物质的量分数）的Bi₂WO₆相比于Bi₂WO₆的光催化降解性能最好。此外,通过X射线粉末衍射、红外光谱、扫描电镜、荧光光谱、X射线光电子能谱和拉曼光谱等一系列表征,对Br掺杂后催化剂的物相组成、微观形貌、光生电荷分离率和光学性质等进行分析。最后进行了自由基捕获实验并提出了可能的光催化机理。     

亚硫酸盐协助中空Bi2WO6微球的光催化性能

本文利用亚硫酸盐与Bi2WO6协同作用,有效地提升其光催化活性。以甲基橙和抗生素环丙沙星(CIP)作为被降解物对该体系的光催化降解性能和机理进行了研究。结果表明:光催化活性增强主要原因为亚硫酸盐能与Bi2WO6的光生空穴及羟基自由基反应,不仅能生成新的活性物质亚硫酸自由基(SO3^2-),还能促进Bi2WO6光生电子—空穴对的分离。此外,还考察了催化剂的用量、和污染物的浓度对该体系光催化性能的影响。     

一种多季胺阳离子诱导Bi2WO6片状团簇微球的合成及光致发光特性

以一种实验室自合成的双子季铵盐为表面活性剂,采用水热法,通过调节pH值,制备出由Bi2WO6纳米片自组装而成的不同片状团簇微球。研究了不同Bi2WO6片状团簇微球的物相结构、成分、晶体形貌和光致发光特性,探讨了其可能的生长机理。结果表明,在这种多季胺阳离子作用下,pH值对Bi2WO6片状团簇微球的物相、形貌和光致发光性能有明显的影响,随着pH值的增大,Bi2WO6片状团簇微球在(131)晶面处呈现明显的择优取向生长,在pH=5时,Bi2WO6微球可达到最大的发光强度。     

MOF-808/Bi2MoO6复合材料的构筑及其光催化性能

采用简单的两步水热法制备出了锆基金属有机骨架和钼酸铋的复合材料MOF-808/Bi₂MoO₆。通过X射线粉末衍射、傅里叶红外光谱、扫描电子显微镜、透射电子显微镜、X射线光电子能谱、紫外可见漫反射光谱、N₂吸附-脱附测试和电化学测试对所制备材料的组成、微观结构、光学性质以及光生载流子的复合效率进行了分析。与纯Bi₂MoO₆和MOF-808相比,0.5%-MOF-808/Bi₂MoO₆复合材料展示出了较高的光催化活性,在可见光照射120 min时对抗生素环丙沙星(CIP)的降解率达89.7%。通过自由基捕获实验,证明了·O₂^-是主要活性物种,基于此我们提出了可能的光催化降解机理。     

Ag/Bi2WO6复合材料的制备及光催化性能

采用一步水热合成法制得花球状Bi_2WO_6和Ag/Bi_2WO_6光催化剂,借助X射线衍射(XRD)、场发射扫描电子显微镜(FES-EM)、透射电子显微镜(TEM)、X射线光电子能谱分析(XPS)、紫外-可见分光光度法(UV-Vis)等手段对样品进行结构性能表征。模拟日光的条件下,以甲基橙(MO)为降解物,对Bi_2WO_6和Ag/Bi_2WO_6的催化活性和机理进行研究。结果表明,相对Bi_2WO_6,相同条件下Ag/Bi_2WO_6对MO具有更佳的降解效果,当Ag掺杂量为1%(n/n)时,其降解率(180 min)可达到91.4%,同时一次回收样降解率也达到81%。此外,也对Ag/Bi_2WO_6复合材料的降解机理做了初步探究。     

Polymorphism in Bi2WO6

The polymorphism of Bi₂WO₆ has been studied using differential dilatometry and differential thermal analysis with polycrystalline specimens prepared by sintering the oxides Bi₂O₃ and WO₃. Two reversible polymorphic transitions were observed, one at 662°C and one at 962°C. The former transition showed a very small change of enthalpy and very little dimensional change, while the latter showed a large thermal hysteresis, had a large change of enthalpy, and was accompanied by a sizable volume change. The high-temperature powder X-ray data indicated that the intermediate phase as well as the low-temperature form had orthorhombic symmetry and the high-temperature form had monoclinic symmetry. The 662°C transition is displacive and the 962°C transition reconstructive. A crystal structure of the high-temperature form is proposed and discussed in comparison with that of the low-temperature form.     

Preparation and visible light photocatalytic activity of Bi2O3/Bi2WO6 heterojunction photocatalysts

The Bi₂O₃/Bi₂WO₆ heterojunction photocatalysts were prepared by a two-step solvothermal process using Bi(NO₃)₃-ethylene glycol solution as Bi source. The catalysts were characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-vis diffuse reflection spectroscopy. The heterostructure catalysts are composed of Bi₂O₃ nanoparticles as modifier and 3D Bi₂WO₆ microspheres as substrate. Bi₂O₃ nanoparticles with diameters of about 10-15 nm are tightly grown on the lateral surface of the Bi₂WO₆ microspheres. The hierarchical Bi₂O₃/Bi₂WO₆ microspheres exhibit higher photocatalytic activity than the single phase Bi₂WO₆ or Bi₂O₃ for the degradation of rhodamine B under visible light illumination (λ>420 nm). The enhancement of the photocatalytic activity of the Bi₂O₃/Bi₂WO₆ heterojunction catalysts can be ascribed to their improved light absorption property and the reduced recombination of the photoexcited electrons and holes during the photocatalytic reaction. The effect of loading amount of Bi₂O₃ on the catalytic performance of the heterojunction catalysts was also investigated and the optimal content of Bi₂O₃ is 3 wt%. The Bi₂O₃/Bi₂WO₆ heterojunction photocatalysts are essentially stable during the photocatalytic process.     

Bi2WO6/UiO-66复合材料的制备及其光催化性能

通过水热法制备了一种复合光催化剂Bi_2WO_6/UiO-66,探究了模板剂乙酸(CH_3COOH)对Ui O-66形貌的影响和2种中心元素Bi与Zr的不同物质的量之比对光催化性能的影响。通过XRD、SEM、N_2吸附-脱附、UV-Vis DRS、XPS等对催化剂的物相、形貌、比表面积、光吸收性能、元素组成等进行表征。实验结果表明,当n_(Bi)∶n_(Zr)=2∶1时,Bi_2WO_6/UiO-66对罗丹明B(RhB)的光催化活性最高,可见光照射50 min后,RhB的相对浓度降低98.5%。经过5次循环利用实验,催化剂的光催化活性没有明显下降,说明复合光催化剂的稳定性高。根据自由基捕获实验证明了空穴(h~+)为光催化中起决定性作用的活性物质,结合电化学测试以及UV-Vis DRS表征提出了可能的光催化降解机理。     

Bi2WO6 photocatalytic films fabricated by layer-by-layer technique from Bi2WO6 nanoplates and its spectral selectivity

Bi₂WO₆ multilayer films have been fabricated successfully by a layer-by-layer (LbL) technique from Bi₂WO₆ nanoplates, which show higher visible-light photoactivity (λ>420 nm) than that of Bi₂WO₆ nanoplate powders and P25 TiO₂ films. The films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and UV-visible absorption spectroscopy. Photocatalytic activities of the films were evaluated by the rhodamine B (RhB) decomposition under UV and visible-light irradiation. Thickness and photoactivity of the film can be modified easily by changing the deposition cycles. Bi₂WO₆ films have the spectral selectivity of the photocatalytic degradation of RhB. Under the wavelength greater than 300 nm, the RhB molecules tend to be transformed to rhodamine over Bi₂WO₆ films selectively. However, in the case of shorter wavelength (λ=254 nm) light irradiation, the RhB molecules can be photodegraded completely.     

Bi2WO6/g-C3N4复合型催化剂的制备及其可见光光催化性能

利用溶剂热法, 把Bi₂WO₆纳米颗粒植入g-C₃N₄层间和表面成功地制备了Bi₂WO₆/g-C₃N₄复合型光催化剂。通过XRD、SEM、TEM、BET和UV-Vis分别对样品的结构、组成、形貌、比表面积、光学性能进行了表征。结果表明, g-C₃N₄层状结构被部分剥离成碎片且与Bi₂WO₆纳米颗粒形成了复合物。Bi₂WO₆/g-C₃N₄复合型光催化剂与单一Bi₂WO₆相比不仅扩展了可见光的响应范围、增大了比表面还加速了光生电子与空穴的分离。结果表明, Bi₂WO₆的最佳负载量为60wt%时, 复合型光催化剂具有最高的可见光催化活性且性能稳定、易回收。     

Bi2WO6/g-C3N4复合型催化剂的制备及其可见光光催化性能

利用溶剂热法,把Bi2WO6纳米颗粒植入g-C3N4层间和表面成功地制备了Bi2WO6/g-C3N4复合型光催化剂。通过XRD、SEM、TEM、BET和UV-Vis分别对样品的结构、组成、形貌、比表面积、光学性能进行了表征。结果表明,g-C3N4层状结构被部分剥离成碎片且与Bi2WO6纳米颗粒形成了复合物。Bi2WO6/g-C3N4复合型光催化剂与单一Bi2WO6相比不仅扩展了可见光的响应范围、增大了比表面还加速了光生电子与空穴的分离。结果表明,Bi2WO6的最佳负载量为60wt%时,复合型光催化剂具有最高的可见光催化活性且性能稳定、易回收。     

Cooperative self-construction and enhanced optical absorption of nanoplates-assembled hierarchical Bi2WO6 flowers

Bi₂WO₆ hierarchical multilayered flower-like assemblies are fabricated on a large scale by a simple hydrothermal method in the presence of polymeric poly(sodium 4-styrenesulfonate). Such 3D Bi₂WO₆ assemblies are constructed from orderly arranged 2D layers, which are further composed of a large number of interconnected nanoplates with a mean side length of ca. 50 nm. The bimodal mesopores associated with such hierarchical assembly exhibit peak mesopore size of ca. 4 nm for the voids within a layer, and peak mesopore size of ca. 40 nm corresponding to the interspaces between stacked layers, respectively. The formation process is discussed on the basis of the results of time-dependent experiments, which support a novel ‘coupled cooperative assembly and localized ripening’ formation mechanism. More interestingly, we have noticed that the collective effect related to such hierarchical assembly induces a significantly enhanced optical absorbance in the UV-visible region. This work may shed some light on the design of complex architectures and exploitation of their potential applications.