Preparation, characterization, and photocatalytic activity of polyaniline/ZnO nanocomposite

Polyaniline (PANI)/zinc oxide (ZnO) nanocomposite was synthesized by in-situ polymerization. X-ray diffraction patterns, UV?Cvisible spectroscopy, SEM, and TEM were used to characterize the composition and structure of the nanocomposite. Nanostructured PANI/ZnO composite was used as photocatalyst in the photodegradation of methylene blue dye molecules in aqueous solution. The photocatalytic activity of PANI/ZnO nanocomposite under UV and visible light irradiation was evaluated and was compared with that of ZnO nanoparticles. ZnO/PANI core?Cshell nanocomposite had greater photocatalytic activity than ZnO nanoparticles and pristine PANI under visible light irradiation. According to these results, application of PANI as a shell on the surface of ZnO nanoparticles causes the enhanced photocatalytic activity of the PANI/ZnO nanocomposite. Also UV?Cvisible spectroscopy studies showed that the absorption peak for PANI/ZnO nanocomposite has a red shift toward visible wavelengths compared with the ZnO nanoparticles and pristine PANI. The effect of different operating conditions on the photocatalytic performance of PANI/ZnO nanocomposite in the photodegradation of methylene blue dye molecules was investigated in a bath experimental setup.     

Preparation,characterization and photocatalytic performance of polyoxometalate / polyaniline / titania ternary composite

A new CoW₁₁Mn/PANI/TiO₂ ternary composite was synthesized with K₈[Co(H₂O)MnW₁₁O₃₉] (CoW₁₁Mn) and PANI/TiO₂ by electrostatic self-assembly. These catalysts were characterized using infrared (IR) spectroscopy, X-ray diffraction, scanning electron microscopy, ultraviolet–visible spectroscopy, and N₂ adsorption–desorption. CoW₁₁Mn/PANI/TiO₂ was used to photodegradate the example contaminant, gentian violet (GV). Under the optimum photodegradation conditions, 92.63% degradation was achieved, indicating that the introduction of polyoxometalate and polyaniline greatly enhanced the photocatalytic performance of the catalyst. Moreover, CoW₁₁Mn/PANI/TiO₂ exhibits stable performance with little loss in activity after three successive runs. Thus, CoW₁₁Mn/PANI/TiO₂ ternary composite could be a promising photocatalyst in photodegradation of organic pollutants.     

Synthesis and characterization of conductive polyaniline/TiO2 composite nanofibers

Fibrillar conductive polyaniline/TiO₂ (PANI/TiO₂) nanocomposites with different TiO₂ amount were synthesized with a template-free in situ polymerization method and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and conductivity measurement. The morphology determination shows that the PANI/TiO₂ composite nanofibers are relatively uniform with the diameter and length in the range of 20–40 nm and 390–420 nm respectively. It also shows that the TiO₂ of the composite is rutile crystalline and PANI has some degree of crystallinity. The IR measurement indicates that there is a strong interaction between the PANI and TiO₂ nanoparticles, and it has a beneficial effect on the thermal stability of the composite nanofiber. The conductivity of PANI/TiO₂ composites changes with TiO₂ amount and reaches an optimum value of 2.86 S/cm at 11.1 wt% TiO₂. Translated from Journal of Northwest Normal University (Natural Science), 2006, 42(4): 67–70 (in Chinese)     

Synthesis, characterization and visible light photocatalytic properties of Bi2WO6/rectorite composites

Visible light-induced Bi(2)WO(6)/rectorite (BR) composites were prepared by a sol-gel method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectrum, Fourier transform infrared (FTIR) spectrum, X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmet-Teller (BET). The UV absorption edges of the BR-450 catalyst showed a marked red shift as compared to that of the pure Bi(2)WO(6). The photocatalytic activities of the as-prepared samples were evaluated by the photocatalytic degradation of 4BS dye in aqueous solution under visible light irradiation (>420 nm). The results showed that the BR-450 catalyst exhibited a strong adsorption capability and a higher photocatalytic degradation activity than the pure Bi(2)WO(6) for 4BS dye, which could be attributed to the synergetic effects of the adsorbability of rectorite and the photocatalytic property of Bi(2)WO(6) in it.     

Synthesis and photocatalytic activity of TiO2/conjugated polymer complex nanoparticles

A photocatalyst of nanometer TiO2/conjugated polymer complex was successfully synthesized and characterized by spectroscopic methods and photocatalytic experiments. The complex photocatalyst could be activated by absorbing both ultraviolet and visible light （λ = 190-800 nm）. Methylene blue （MB） could be degraded more efficiently on the complex photocatalyst than on the TiO2 under natural light. The conjugated polymer played a promoting role in the photocatalytic degradation of MB. The calcination temperature had an important effect in degradation of dye and could be summarized as 260℃ 〉 300 ℃ 〉 340 ℃ 〉 220 ℃ 〉 180 ℃.     

BiOBr/HPW/Au的制备及其光催化性能的研究

采用水热法和光还原法制备了BiOBr/HPW/Au光催化剂。表征结果表明，BiOBr/HPW/Au光催化剂成功制备，在可见光照射下，BiOBr/HPW/Au具有良好的光催化降解罗丹明B活性，其一级反应动力学速率常数是BiOBr的3.55倍。捕获剂实验结果表明，该反应过程中主要的活性物种是·O₂^-，BiOBr/HPW/Au具有高光催化活性的主要因为是BiOBr、HPW和Au纳米粒子三者的相互作用，提高了BiOBr对可见光的吸收以及电子-空穴对的分离效率，进而提高BiOBr的可见光催化活性。     

Synthesis, characterization and photocatalytic property of AgBr/BiPO4 heterojunction photocatalyst

A novel heterojunction AgBr/BiPO(4) photocatalyst was synthesized with the hydrothermal method. The photocatalyst was characterized by X-Ray powder Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectrometry (EDS), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectrscopy (XPS) and Diffuse Reflectance Spectroscopy (DRS). The XRD, SEM-EDS, TEM and XPS analyses indicated that the heterojunction structure formed during the process of hydrothermal treatment. The photocatalytic activity of the photocatalysts was evaluated by degradation of methylene blue dye (MB). The results indicated that the AgBr/BiPO(4) heterojunction exhibited a much higher photocatalytic activity than the pure BiPO(4). The mechanism of the enhancing AgBr/BiPO(4) heterojunction's photocatalytic activity was discussed. It was also found that the photocatalytic degradation of MB over AgBr/BiPO(4) heterojunction photocatalysts followed the pseudo-first-order reaction model.     

Synthesis,characterization and photocatalytic activity of a new type of high-efficiency polyacid composite

In order to achieve the degradation of Congo red dye in wastewater, a new type of three-dimensional porous composite catalyst PW₇Mo₃Cu₂/PANI/MnO₂ was prepared by using heteropoly acid [TBA]₄H₃[PW₇Mo₃Cu₂O₃₈(H₂O)₂] doped intermediate PANI/MnO₂. Using IR, UV, SEM, XPS and other characterization techniques, it was confirmed that the heteropoly acid [TBA]₄H₃[PW₇Mo₃Cu₂O₃₈(H₂O)₂] was successfully doped into the intermediate PANI/MnO₂ to form a three-dimensional porous structure. The results of N₂ adsorption–desorption experiment indicated that the composite catalyst belongs to the type IV (a) mesoporous structure material and has a large pore size and specific surface area. Then, the composite catalyst PW₇Mo₃Cu₂/PANI/MnO₂ was used to photocatalyze the degradation of Congo red dye. Under the best photocatalytic conditions, the decolorization rate of Congo red dye reached 93.84%. After recovering and repeating the photocatalysis experiment three times, the decolorization rate of Congo red dye was 73.18%. The experimental results proved that the novel composite catalyst has a strong ability to degrade Congo red dye and reusability, and has potential application value.

     

Preparation and characterization of RuO2/polyaniline composite electrodes

RuO₂–polyaniline (PANI) composites have been prepared by a novel method resulting in a composite material at the electrode surface. The method is based on the utilization of the chemical oxidation of aniline by the RuO₂ attached to the gold substrate in acid media. Electrochemical quartz crystal nanobalance combined with cyclic voltammetric and chronoamperometric measurements was used to study the oxidative deposition process as well as the exchange of ions and solvent molecules during cycling. The chemical reaction between RuO₂ and aniline results in a surface mass increase at the open circuit, and it also manifests itself in the substantial decrease of the open-circuit potential after addition of aniline into the supporting electrolyte. The potential range, the nature of the electrolyte, and the pH have been varied. The results of the piezoelectric nanogravimetric studies obtained for the redox transformation of RuO₂ and the composites are elucidated by the transport of ions and water molecules. It has been shown that the behavior of RuO₂ as well as of the composites strongly depends on the spontaneous and potential-dependent solvent sorption, the nature of the electrolyte, and the potential range. It has been found that the value of the specific capacitance was substantially increased by the polyaniline present without any significant deterioration of stability of the capacitor.     

Synthesis and characterization of polyaniline filled PU/PMMA interpenetrating polymer networks

A series of conducting interpenetrating polymer networks (IPNs), are prepared by sequential polymerization of castor oil based polyurethane (PU) with poly(methyl methacrylate) (PMMA) and polyaniline doped with camphor sulphonic acid (PAni)_CSA. The effect of different amount of PAni (varies from 2.5-12.5%) on the properties of PU/PMMA (50/50) IPNs such as electrical properties like conductivity, dielectric constant and dissipation factor; mechanical properties like tensile strength and percentage elongation at break have been reported. (PAni)_CSA filled IPNs shows improved tensile strength than the unfilled IPN system. The thermal stability and surface morphology of unfilled and (PAni)_CSA filled PU/PMMA (50/50) IPN sheets were investigated using a thermogravimetric analyzer (TGA) and a scanning electron microscope (SEM). TGA thermograms of (PAni)_CSA filled PU/PMMA (50/50) IPNs show a three-step thermal degradation process. SEM micrograms of filled PU/PMMA IPN system shows spherulitic structure at higher concentration of (PAni)_CSA.     

Synthesis and structure of Bi2Ce2O7: a new compound exhibiting high solar photocatalytic activity

A facile method of solution combustion was used to synthesize a new solid solution Bi(2)Ce(2)O(7). The structure was determined from powder X-ray diffraction (PXRD) and found to crystallize in the space group Fm3m with cell parameter a = 5.46936(9) ?. The particle sizes varied from 5 to 6 nm. The degradation of cationic dye malachite green (MG) was investigated under solar radiation as the band gap of the material is 2.34 eV.     

Synthesis and characterization of TiO2/C Janus composite particles and its photocatalytic activity for the degradation of rhodamine B

Janus materials with anisotropic chemical structures and physical properties have attracted increasing attention due to their diversified potential applications. In this paper, titanium dioxide/3-(trimethoxysilyl) propylmethacrylate (TiO₂/MPS) was obtained by swelling assisted with extrusion of PS@TiO₂. Then, the phenolic resin (PF) was coated on the surface of MPS lobe. Finally, TiO₂/C Janus composite particles were obtained by sintering at the atmosphere of nitrogen. The middle objects during reactive process and the final product were systematically characterized. Results showed that the Janus porous particles of TiO₂/C were snowman-like structure, in which the average diameter of the carbon lobe was 178 nm and that of TiO₂ lobe was 226 nm. When used as photocatalysts for Rhodamine B degradation in aqueous solution under UV irradiation, the resulted Janus product exhibited more efficient photocatalytic activity than TiO₂ hollow microspheres. Graphical abstract

Schematic illustration of swelling polymerization approach to synthesize TiO₂/C Janus composite particles and its photocatalytic activity for the degradation of rhodamine B     

棒状结构Pt/PbWO4微米晶的合成、表征及其高光催化性能

PbWO4是一类重要的半导体,广泛运用于高能物理领域无机闪烁晶体.它具有许多独特的物理性能,如衰减时间短(10 ns)、能量密度高(8.28 cm3)、低光产率(300 photons/MeV)、短辐射长度(0.9 cm)和高抗辐照损伤等. PbWO4纳米晶体的激子荧光、热荧光和其它光学性能主要取决PbWO4晶体的形貌和微观结构.目前已经合成了不同结构的PbWO4纳米/微米晶体,如四角双锥微米晶、微米球、纳米棒、纳米纺垂体等.近年来, PbWO4的光催化性能也引起人们的重视.研究发现, PbWO4晶体的光催化性能和其形貌、微观结构密切相关.如在不同形貌的十四面体、三维多尺度微米球和纳米颗粒中, PbWO4微米球表现了极高的光催化活性.此外, PbWO4微米球由于密度大,非常容易分离,从而有利于其回收利用,在循环使用时具有很高的稳定性.因此,合成具有特殊形貌的PbWO4纳米/微米晶体具有重要的理论和现实意义.此外,合成贵金属/半导体复合纳米结构是提高光催化性能的另一有效策略.在贵金属/半导体复合纳米结构中,光生电子(e–)和(h+)的复合可以在很大程度上得到抑制,因为光生e–可以快速地迁移至贵金属颗粒中心,从而加速e–和h+的分离.本文利用水热结合焙烧法首先合成了长度大于1μm的棒状PbWO4微米晶.然后利用光化学沉积法,在PbWO4微米晶表面沉积不同含量(0.5 wt%,1 wt%,和2 wt%)的Pt纳米粒子.利用X射线衍射(XRD)、N2物理吸附、扫描电镜(SEM)、透射电镜(TEM)、光电子能谱(XPS)、光致发光谱(PL)和紫外-可见漫反射吸收光谱(UV-Vis DRS)等手段对所制PbWO4和Pt/PbWO4进行了表征.表征结果表明,合成的PbWO4和Pt/PbWO4的比表面积很小(1.5–1.9 m2/g),沉积的Pt纳米粒子为金属态. UV-Vis DRS测试表明,沉积的Pt纳米粒子在光照下可以产生表面等离子共振,促进可见光的吸收.另外, PL的结果则证实Pt纳米粒子的存在还可抑制PbWO4晶体在光照下产生的光生e–和h+的分离.而XRD和高分辨TEM分析表明PbWO4微米棒的晶体生长方向为(–102)晶体方向.电子选区衍射表明,棒状PbWO4微米晶具有极高的结晶度.以氙灯为光源进行了光催化降解染料酸性橙II的光催化性能测试.结果表明,当沉积1–2 wt%Pt纳米粒子时,可使光催化活性提高2倍左右.另外, Pt/PbWO4微米棒的密度较大,非常容易进行离心分离催化剂及其循环使用.在第一次使用时酸性橙II的降解率为93%,而在第四次使用时酸性橙II的降解率仍维持在88%,表现出很好的光催化稳定性. Pt/PbWO4具有很高的光催化活性的原因,一方面是由于其具有很高的结晶度和独特的棒状结构,另一方面是由于沉积的Pt纳米粒子在光照下可以产生表面等离子共振,促进了可见光的吸收和光生e–与h+的分离.     

Magnetically retrievable Bi2WO6/Fe3O4/Na-MMT composite: fabrication and photocatalytic activity

Research on Chemical Intermediates - Magnetically retrievable bismuth tungstate/iron oxide/sodium montmorillonite composite (Bi2WO6/Fe3O4/Na-MMT) was synthesized via a simple solvothermal process....     

Sn/Cu-TiO2 nanoparticles produced via sol-gel method: Synthesis,characterization, and photocatalytic activity

TiO₂ and Sn/Cu-TiO₂ nanoparticles with different Sn/Cu contents have been synthesized and characterized by different analysis methods such as XRD, TEM, and BET. Sn/Cu-TiO₂ was preferential to TiO₂ with 2,5-fold increase in photodegradation rate of different types of dyes such as methyl orange, methylene blue and methyl red. This activity was relevant to the influences of co-doping on the physicochemical properties and surface interfacial charge transfer mechanisms. An optimum synergetic effect was found for a mass ratio of Sn/TiO₂ equal to 0.75% and Cu/TiO₂ equal to 0.5%. The degradation reaction fit well to a Langmuir-Hinshelwood kinetic model indicating the reaction rate is depended on initial adsorption step.     

异质结构AgCl/Bi2WO6微米球制备、表征及其光催化性能

首先利用水热法制备了由纳米片组装的粒径为1.5–2μm的Bi2WO6微球,然后在微球表面沉积了不同含量的AgCl (5 wt%,10wt%,20wt%,30wt%),制备了异质结构AgCl/Bi2WO6微球光催化剂.利用X射线粉末衍射、扫描电镜、透射电镜、红外光谱、紫外-可见漫反射吸收等手段对所制的光催化剂进行表征,并以紫外光和可见光分别为光源,罗丹明B为降解对象测试了其光催化活性,考察复合不同含量的AgCl对Bi2WO6光催化剂的性能影响.结果表明,沉积AgCl对Bi2WO6的晶体结构、表面性能和光吸收性能没有产生明显影响,但大幅度提高了Bi2WO6的紫外和可见光催化活性.当复合20wt%AgCl时, AgCl/Bi2WO6光催化活性最佳,紫外光下比纯Bi2WO6提高了2.2倍,可见光下提高了1倍.这主要是由于形成的AgCl/Bi2WO6异质结能有效抑制光生电子和空穴的复合,从而提了其光催化性能.     

具有可见光催化活性的Ag_3PO_4/NaNbO_3复合材料的合成与表征

采用共沉淀法制备了Ag_3PO_4/NaNbO_3复合半导体光催化剂,利用X-射线衍射、X射线光电子能谱、紫外漫反射和扫描电镜等方法对合成样品进行表征.测试了样品对亚甲基蓝溶液的光催化降解活性,复合材料的催化活性远高于单体的Ag_3PO_4和NaNbO_3.     

Preparation and characterization of conducting polyaniline layered magnetic nano composite polymer particles

Considering the application potentials of organic materials possessing both conducting and ferromagnetic functions in various electronic devices, an attempt was made to prepare conducting polyaniline (PANI) layered magnetic nano composite polymer particles. Two routes were used to modify magnetic Fe₃O₄ core particles. In one route, seeded emulsion polymerization of methyl methacrylate (MMA) was carried out in presence of nano‐sized Fe₃O₄ core particles. In another route, cross‐linker ethyleneglycol dimethacrylate (EGDM) was used in addition to MMA. The modified composite particles were named as Fe₃O₄/PMMA and Fe₃O₄/P(MMA‐EGDM), respectively. Finally, seeded chemical oxidative polymerization of aniline was carried out in the presence of Fe₃O₄/PMMA and Fe₃O₄/P(MMA‐EGDM) composite seed particles to obtain Fe₃O₄/PMMA/PANI and Fe₃O₄/P(MMA‐EGDM)/PANI composite polymer particles. The modification of Fe₃O₄ core particles was confirmed by electron micrographs, FTIR, UV–visible spectra, X‐ray photoelectron spectra, X‐ray diffraction pattern and thermogravimetric analyses. A comparative study showed that crosslinking of intermediate shell improved the magnetic susceptibility and electrical conductivity of PANI layered magnetic nano composite particles. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis, structure, negative thermal expansion, and photocatalytic property of Mo doped ZrV2O7

A new series of compounds identified in the phase diagram of ZrO(2)-V(2)O(5)-MoO(3) have been synthesized via the solution combustion method. Single crystals of one of the compounds in the series, ZrV(1.50)Mo(0.50)O(7.25), were grown by the melt-cool technique from the starting materials with double the MoO(3) quantity. The room temperature average crystal structure of the grown crystals was solved using the single crystal X-ray diffraction technique. The crystals belong to the cubic crystal system, space group Pa3 (No. 205) with a = 8.8969 (4) ?, V = 704.24 (6) ?(3), and Z = 4. The final R(1) value of 0.0213 was achieved for 288 independent reflections during the structure refinement. The Zr(4+) occupies the special position (4a) whereas V(5+) and Mo(6+) occupy two unique (8c) Wyckoff positions. Two fully occupied O atoms, (24d) and (4b), one partially occupied O atom (8c) have been identified for this molybdovanadate, which is a unique feature for these crystals. The structure is related to both ZrV(2)O(7) and cubic ZrMo(2)O(8). The temperature dependent single crystal studies show negative thermal expansion above 370 K. The compounds have been characterized by powder X-ray diffraction, solid-state UV-vis diffuse reflectance spectra, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The photocatalytic activity of these compounds has been investigated for the degradation of various dyes, and these compounds show specificity toward the degradation of non-azoic dyes.     

Preparation, characterization and photocatalytic activity of Co3O4/LiNbO3 composite

The Co₃O₄/LiNbO₃ composites were synthesized by impregnation of LiNbO₃ in an aqueous solution of cobalt nitrate and next by calcination at 400°C. The activity of produced samples has been investigated in the reaction of photocatalytic hydrogen generation. The crystallographic phases, optical and vibronic properties were studied using X-ray diffraction (XRD), diffuse reflectance (DR) UV-vis and resonance Raman spectroscopic techniques, respectively. The influence of cobalt content (range from 0.5 wt.% to 4 wt.%) on the photocatalytic activity of Co₃O₄/LiNbO₃ composites for photocatalytic hydrogen generation has been investigated. Co₃O₄/LiNbO₃ composites exhibited higher than LiNbO₃ photocatalytic activity for hydrogen generation. The highest H₂ evolution efficiency was observed for Co₃O₄/LiNbO₃ composite with 3 wt.% cobalt content. The amount of H₂ obtained in the presence of LiNbO₃ and Co₃O₄/LiNbO₃ (3 wt.% of cobalt content) was 1.38 µmol/min and 2.59 µmol min^?1, respectively.