Facile Electrospinning of CeO2/Bi2WO6 Heterostructured Nanofibers with Excellent Visible‐light‐driven Photocatalytic Performance

One‐dimensional (1D) CeO₂/Bi₂WO₆ heterostructured nanofibers with a diameter of about 300 nm were successfully synthesized by using a straightforward strategy combining an electrospinning technique with a sintering process. The acquired products were characterized by thermogravimetric and differential scanning calorimetric (TG‐DSC), Fourier transform infrared (FT‐IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area measurements, and UV/Vis spectroscopy. The obtained CeO₂/Bi₂WO₆ heterostructured nanofibers exhibited an excellent photocatalytic property for the degradation of Rhodamine B (RhB) dye driven by visible light due to the promoted separation of photoelectrons and holes and the large contact area between the photocatalyst and organic pollutant.     

Novel Bi2WO6‐coupled Fe3O4 Magnetic Photocatalysts: Preparation,Characterization and Photodegradation of Tetracycline Hydrochloride

Novel Bi₂WO₆‐coupled Fe₃O₄ magnetic photocatalysts with excellent and stable photocatalytic activity for degrading tetracycline hydrochloride and RhB were successfully synthesized via a facile solvothermal route. Through the characterization of the as‐prepared magnetic photocatalysts by X‐ray diffractometry, scanning electron microscopy, transmission electron microscopy, X‐ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectra, it was found that the as‐prepared magnetic photocatalysts were synthesized by the coupling of Bi₂WO₆ and Fe₃O₄, and introduction of appropriated Fe₃O₄ can improve nanospheres morphology and visible‐light response. Among them, BFe2 (0.16% Fe₃O₄) exhibited the best photocatalytic activity for degradation of tetracycline hydrochloride (TCH), reaching 81.53% after 90 min. Meanwhile, the as‐prepared magnetic photocatalysts showed great separation and recycle property. Moreover, the results of electrochemical impedance spectroscopy demonstrated that the well conductivity of Fe₃O₄ can promote photogenerated charge carriers transfer and inhibit recombination of electron–hole pairs, so that Bi₂WO₆/Fe₃O₄ exhibited enhanced photocatalytic activity on degradation of TCH and RhB. Hence, this work provides a principle method to synthesize Bi₂WO₆/Fe₃O₄ with excellent photocatalytic performance for actual application, in addition, it showed that introduction of Fe₃O₄ not only can provide magnetism, but also can enhance photocatalytic activity of Bi₂WO₆/Fe₃O₄ magnetic photocatalysts.     

Synthesis of Bi2WO6/Bi2O3 Composite with Enhanced Photocatalytic Activity by a Facile One‐step Hydrothermal Synthesis Route

In this study, the characterization and photocatalytic activity of Bi₂WO₆/Bi₂O₃ under visible‐light irradiation was investigated in detail. The results suggested that Bi₂WO₆/Bi₂O₃ can be synthesized by a facile one‐pot hydrothermal route using a super big 200 mL Teflon‐lined autoclave with optimal sodium oleate/Bi molar ratio of 1.25. Through the characterization of Bi₂WO₆/Bi₂O₃ by X‐ray diffraction, scanning electron microscopy, X‐ray photoelectron spectroscopy, Fourier transform infrared, UV‐vis diffuse reflectance spectra and Photoluminescence spectra, it was found that the as‐prepared composite possessed smaller crystallite size and higher visible‐light responsive than the pure Bi₂WO₆. Moreover, it was expected that the as‐prepared composites exhibited enhanced photocatalytic activity for the degradation of Rhodamine B under visible‐light irradiation, which could be ascribed to their improved light absorption property and the reduced recombination of the photogenerated electrons and holes during the photocatalytic reaction. In general, this study could provide a principle method to synthesize Bi₂WO₆/Bi₂O₃ with enhanced photocatalytic activity by one‐step hydrothermal synthesis route for environmental purification.     

Samarium and Nitrogen Co‐Doped Bi2WO6 Photocatalysts: Synergistic Effect of Sm3+/Sm2+ Redox Centers and N‐Doped Level for Enhancing Visible‐Light Photocatalytic Activity

Samarium and nitrogen co‐doped Bi₂WO₆ nanosheets were successfully synthesized by using a hydrothermal method. The crystal structures, morphology, elemental compositions, and optical properties of the prepared samples were investigated. The incorporation of samarium and nitrogen ions into Bi₂WO₆ was proved by X‐ray diffraction, energy dispersive X‐ray spectroscopy, and X‐ray photoelectron spectroscopy. UV/Vis diffuse reflectance spectroscopy indicated that the samarium and nitrogen co‐doped Bi₂WO₆ possessed strong visible‐light absorption. Remarkably, the samarium and nitrogen co‐doped Bi₂WO₆ exhibited higher photocatalytic activity than single‐doped and pure Bi₂WO₆ under visible‐light irradiation. Radical trapping experiments indicated that holes (h⁺) and superoxide radicals ( ^. O₂^?) were the main active species. The results of photoluminescence spectroscopy and photocurrent measurements demonstrated that the recombination rate of the photogenerated electrons and holes pairs was greatly depressed. The enhanced activity was attributed to the synergistic effect of the in‐built Sm³⁺/Sm²⁺ redox pair centers and the N‐doped level. The mechanism of the excellent photocatalytic activity of Sm‐N‐Bi₂WO₆ is also discussed.     

Ag@Bi2WO6Composites with High Visible‐Light‐Driven Photocatalytic Activities Prepared in UV Light Irradiation

Bi₂WO₆ microstructures were synthesized through hydrothermal process and Ag@Bi₂WO₆ composites were synthesized by simple UV light irradiation for 5 min using Bi₂WO₆ and AgNO₃ as raw materials. Ag@Bi₂WO₆ composites were characterized by X‐ray powder diffraction (XRD), field‐emission scanning electron microscopy (FE‐SEM), and UV‐Vis absorption spectrum (UV‐Vis). Few Ag deposited on the Bi₂WO₆ leads to an increase in photocatalytic activity, which clearly indicates that the recombination of photogenerated charge carrier between the hybrid orbital of Bi6s and O2p (valence band) to the empty W5d orbital is inhibited greatly in the Ag@Bi₂WO₆ composite. In addition, a few H₂O₂ will greatly enhance photocatalytic activity of Ag@Bi₂WO₆, and the proper reason is discussed.     

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.     

Construction of NH2-MIL-125(Ti) nanoplates modified Bi2WO6 microspheres with boosted visible-light photocatalytic activity

Photoactive metal–organic frameworks (MOFs) have proven to be a promising porous material in the field of catalysis. Controllable integration of these MOFs with inorganic semiconductor materials may endow new multifunctional hybrid materials with preferable photocatalytic properties. In this research, NH₂-MIL-125(Ti) nanoplates modified Bi₂WO₆ microspheres was prepared via a simple solvothermal method. The photocatalytic behaviors of the acquired catalysts was evaluated via the degradation of tetracycline hydrochloride (TC) under visible light. The experimental results showed that NH₂-MIL-125(Ti)/Bi₂WO₆ composites display higher photocatalytic activity than that of single Bi₂WO₆, and the ideal incorporation amount of NH₂-MIL-125(Ti) was around 5 wt%. The steady state fluorescence spectrum, transient photocurrents and electrochemical impedance spectroscopy verified that the introduction of NH₂-MIL-125(Ti) could accelerate the separation and transfer of photogenerated carriers and thus improve the photocatalytic activity of Bi₂WO₆. The photocatalytic mechanism was explored in detail. This work extends the knowledge of integrating MOFs with traditional photocatalysts to form new composite materials in the area of environmental purification.

     

AgBi(WO4)2: A New Modification Material to Bi2WO6 for Enhanced and Stable Visible‐Light Photocatalyic Performance

In this work, we report a novel AgBi(WO₄)₂–Bi₂WO₆ heterostructure, which was designed and synthesized by using a simple hydrothermal method. Methyl orange was used as a representative dye indicator to evaluate the visible‐light catalytic activity and the catalytic mechanism was investigated. The as‐synthesized AgBi(WO₄)₂–Bi₂WO₆ composite displayed a 43 times higher photocatalytic activity than Bi₂WO₆. Owing to the matched band gap and distinctive heterostructure, AgBi(WO₄)₂–Bi₂WO₆ reveals a high visible‐light response and high‐efficiency utilization of both photogenerated electrons and holes. AgBi(WO₄)₂ reveals a similar energy level to and good lattice match with Bi₂WO₆, which are favorable qualities for band bending and fluent electron transfer. Furthermore, the photoexcited electrons can produce oxygen to generate ^.O₂^? radicals, which is vital for the overall utilization of both holes and electrons. This is the first example of AgBi(WO₄)₂ being used as photocatalytic material.     

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。     

Nanoflower‐Like Bi2WO6 Encapsulated in ORMOSIL as a Novel Photocatalytic Antifouling and Foul‐Release Coating

Herein, the first multi‐purpose antifouling and foul‐release photocatalytic coating based on ORMOSIL thin films doped with nanoflower‐like Bi₂WO₆ is described. Irradiation with visible light of the new films immersed in water produces significant amounts of H₂O₂ by photocatalytic oxidation of water, and allows the degradation of (bio)organic pollutants at the outer surface of the xerogel film.     

煅烧温度对花朵状钨酸铋光催化活性的影响

钨酸铋在水相体系中能光催化降解有机污染物,而对于钨酸铋光催化活性影响因素的研究非常少.本文研究了煅烧温度对花朵状钨酸铋光催化活性的影响.以钨酸钠和硝酸铋为原料,在160°C下水热反应20 h,合成催化剂,并经不同温度煅烧3 h.用X射线衍射(XRD)、拉曼(Raman)光谱、紫外-可见漫反射吸收光谱(UVVis DRS)和荧光(PL)光谱表征样品.结果表明,这些样品具有十分相似的相组成和电子结构.然而,对于水中苯酚的降解,钨酸铋的光催化活性显示出了很大的差异.钨酸铋的光催化活性随着煅烧温度的升高,先上升后下降,最优煅烧温度为350°C,并且不受样品比表面积大小的影响.这些样品的活性差异主要归结于钨酸铋的结晶度、吸光性和表面缺陷对其光生载流子分离效率的综合影响.     

Nitrogen‐doped graphene‐cerium oxide (NG‐CeO2) photocatalyst for the photodegradation of methylene blue in waste water

This study shows a facile approach for the preparation of CeO₂ nanoparticles decorated with porous nitrogen‐doped graphene (NG) nanosheets for effective photocatalytic degradation of methylene blue (MB). NG nanosheets were first synthesized using a hydrothermal method and then nitrogen‐doped graphene‐cerium oxide (NG‐CeO₂) was prepared through mixing of cerium nitrate with different concentrations of NG under ultrasonication followed by hydrothermal treatment. The synthesized nanocomposites were characterized using X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE‐SEM). The photocatalytic activity of the synthesized nanocomposites was analyzed against MB dye. Results showed that the nanocomposites of NG‐CeO₂ have an average particle size of 20 nm. The as‐prepared NG‐CeO₂ nanocomposites exhibited outstanding photocatalytic activity for dye degradation under visible light irradiation, which could be attributed to synergistic effects between the NG nanosheets and CeO₂. The quantum of photodegradation increases with the increase of the NG content in the nanocomposites.     

Preparation of Bi<Subscript>2</Subscript>WO<Subscript>6</Subscript> by Electrospinning: Researching Their Synthesis Mechanism and Photocatalytic Activity

The novel Bi₂WO₆ nanomaterials, which consist of nanosheets and nanoparticles, were successfully synthesized by a combination of electrospinning and calcining processes. The Bi₂WO₆ with different morphologies and microstructures had been obtained in the same experimental conditions. The growth mechanism of such special nanostructures was investigated, and citric acid played an important role in the formation of Bi₂WO₆ nanostructures. The Bi₂WO₆ nanomaterials exhibited excellent photocatalytic property in the photodegradation of the pulping and papermaking wastewater under visible light irradiation. Besides, preparation of the photocatalyst using electrospinning was beneficial for separation and recycling. So, the Bi₂WO₆ nanomaterials have a great potential in application for wastewater treatment in the future.     

Novel hydrostable Z-scheme Ag/CsPbBr3/Bi2WO6 photocatalyst for effective degradation of Rhodamine B in aqueous solution

In this study, a hydrostable Z-scheme Ag/CsPbBr₃/Bi₂WO₆ photocatalyst was designed and fabricated for the degradation of Rhodamine B (RhB). The structural instability of CsPbX₃ perovskites in water is one of the main obstacles that restrict their practical application in photocatalytic wastewater treatment. The photocatalyst was prepared in three steps: passivation of CsPbBr₃ nanocrystals (NCs) with 3-mercaptopropionic acid (MPA), construction of a heterojunction between MPA-passivated CsPbBr₃ NCs and Bi₂WO₆ ultrathin nanosheets, and doping Ag nanoparticles as charge mediators in the heterojunction. The as-obtained 5%Ag/20%CsPbBr₃/Bi₂WO₆ exhibits good stability and excellent photocatalytic activity. The degradation rate is 93.9% in 120 min, which is 4.41 times than that of Bi₂WO₆.     

水热法制备Pr掺杂Bi2WO6三维花状微球的光催化性能

通过水热法制备稀土Pr掺杂Bi₂WO₆三维花状微球,利用XRD、SEM、N₂吸附-脱附、紫外-可见吸收光谱和光致发光光谱对所制备的光催化材料进行表征。通过降解亚甲基蓝评价样品的光催化活性。结果表明,1.0% Pr-Bi₂WO₆样品的可见光催化活性最佳,降解率达到95%。Pr掺杂提高了催化剂的可见光吸收性能并且能够束缚光生电子使得电子空穴对有效分离从而获得强氧化物质。对其光催化降解做出了合理的解释。     

水热法制备Pr掺杂Bi2WO6三维花状微球的光催化性能

通过水热法制备稀土Pr掺杂Bi₂WO₆三维花状微球,利用XRD、SEM、N₂吸附-脱附、紫外-可见吸收光谱和光致发光光谱对所制备的光催化材料进行表征。通过降解亚甲基蓝评价样品的光催化活性。结果表明,1.0% Pr-Bi₂WO₆样品的可见光催化活性最佳,降解率达到95%。Pr掺杂提高了催化剂的可见光吸收性能并且能够束缚光生电子使得电子空穴对有效分离从而获得强氧化物质。对其光催化降解做出了合理的解释。     

One-Dimensional Bi2WO6 Nanofibers Controllable Synthesis by Electrospinning and Enhanced Visible Photocatalytic Degradation Performances

One-dimensional Bi₂WO₆ nanofibers have been successfully synthesized by simple electrospinning processes. XRD, SEM and UV–visible diffuse reflectance spectra were used to characterize the nanofibers. The results indicated that the Bi₂WO₆ was composed of one-dimensional nanofibers, whose diameter was about 50 nm. Besides, the Bi₂WO₆ nanofibers exhibited excellent visible photocatalytic property in the photodegradation of methylene blue.     

Bi2WO6/TiO2纳米管异质结构复合材料的多模式下的光催化活性比较

以TiO₂纳米管为模板,采用多组分自组装结合水热法制备Bi₂WO₆/TiO₂纳米管异质结构复合材料。通过多种技术如X射线衍射（XRD）,X射线光电子能谱（XPS）,N₂吸附-脱附,扫描电镜（SEM）,高分辨透射电镜（HRTEM）和紫外可见漫反射吸收光谱（UV-Vis DRS）考察所制备样品的组成、结构、形貌、光吸收和电子性质。Bi₂WO₆纳米片或纳米粒子分布在TiO₂纳米管上,形成异质结构。随后,通过在紫外、可见和微波辅助光催化模式下降解染料罗丹明B（RhB）来评价复合催化剂的光催化活性。与TiO₂纳米管和Bi₂WO₆相比,Bi₂WO₆/TiO₂-35纳米管在多模式下表现出更优异的光催化活性。与紫外和可见降解模式相比,Bi₂WO₆/TiO₂-35纳米管在微波辅助光催化模式下对RhB的降解效率最高。这种增强的光催化活性源于适量Bi₂WO₆的引入、纳米管独特的形貌特征和降解模式所引起的增强的量子效率。降解过程中的活性物种被证明是h⁺,·OH和·O₂^-自由基。而且,在微波辅助光催化模式下,可产生更多的·OH和·O₂^-自由基。     

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。     

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。