Incorporating Polyoxometalates into a Porous MOF Greatly Improves Its Selective Adsorption of Cationic Dyes

Various polyoxometalates (POMs) were successfully immobilized to the mesoporous coordination polymer MIL‐101 resulting in a series of POM–MOF composite materials POM@MIL‐101 (POM=K₄PW₁₁VO₄₀, H₃PW₁₂O₄₀, K₄SiW₁₂O₄₀). These materials were synthesized by a simple one‐pot reaction of Keggin POMs, tetramethylammonium hydroxide (TMAH), terephthalic acid (H₂bdc), and Cr³⁺ ions. XRD, FTIR, thermogravimetric analyses (TG), inductively coupled plasma (ICP) spectrometry, and energy‐dispersive X‐ray spectroscopy (EDX) collectively confirmed the successful combination of POMs and the porous framework. Further, these composites POM@MIL‐101 with different loading of POMs were achieved by variation of the POM dosage. Notably, the uptake capacity of MIL‐101 towards organic pollutants in aqueous solution was significantly improved by immobilization of hydrophilic POMs into cages of MIL‐101. An uptake capacity of 371 mg g^?1, comparable to that of the graphene oxide sponges, and much higher than that of the commercial activated carbon, was achieved at room temperature in 5 min when dipping 20 mg PW₁₁V@MIL‐101 in the methylene blue (MB) solution (100 mL of 100 mg L^?1 MB solution). Further study revealed that the POM@MIL‐101 composite materials not only exhibited a fast adsorption rate towards dye molecules, but also possessed of selective adsorption ability of the cationic dyes in wastewater. For example, the adsorption efficiency of PW₁₁V@MIL‐101 (10 mg) towards MB (100 mL of 10 mg L^?1) could reach 98 % in the initial 5 min, and it could capture MB dye molecules from the binary mixture of the MB and MO with similar size. Also, the POM@MIL‐101 materials could be readily recycled and reused, and no POM leached in the dye adsorption process.     

Preparation of photocrosslinked sol‐gel composites based on urethane‐acrylic matrix,silsesquioxane sequences,TiO2, and Ag/Au Nanoparticles for use in photocatalytic applications

An acid urethane oligodimethacrylate based on poly(ethylene glycol) was synthesized and used in the preparation of hybrid composites containing silsesquioxane sequences and titania domains formed through sol‐gel reactions along with silver/gold nanoparticles (Ag/Au NPs) in situ photogenerated during the UV‐curing process. The photopolymerization kinetics studied by Fourier transform infrared spectroscopy and photoDSC showed that the photoreactivity of the investigated formulations depends on the amount of titanium butoxide (5–20 wt %) added in the system subjected to UV irradiation. The introduction of 1 wt % AgNO₃/AuBr₃ in formulations slightly improved the degree of conversion but diminished the polymerization rates. The formation of hybrid materials comprising predominantly amorphous TiO₂/SiO₂ NPs, with or without Ag/Au NPs, was confirmed through specific analyses. The evaluation of photocatalytic activity demonstrated that the synthesized hybrid films are suitable for the complete removal of organic pollutants (phenolic compounds) from water under UV irradiation (200–350 min) at low intensity (found in the solar radiation). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1189–1204     

Highly Dispersed Polyoxometalate‐Doped Porous Co3O4 Water Oxidation Photocatalysts Derived from POM@MOF Crystalline Materials

Rational design of earth‐abundant photocatalysts is an important issue for solar energy conversion and storage. Polyoxometalate (POM)@Co₃O₄ composites doped with highly dispersive molecular metal–oxo clusters, synthesized by loading a single Keggin‐type POM cluster into each confined space of a metal–organic framework (MOF), exhibit significantly improved photocatalytic activity in water oxidation compared to the pure MOF‐derived nanostructure. The systematic synthesis of these composite nanocrystals allows the conditions to be tuned, and their respective water oxidation catalytic performance can be efficiently adjusted by varying the thermal treatment temperature and the feeding amount of the POM. This work not only provides a modular and tunable synthetic strategy for preparing molecular cluster@TM oxide (TM=transition metal) nanostructures, but also showcases a universal strategy that is applicable to design and construct multifunctional nanoporous metal oxide composite materials.     

Preparation for Magnetic Nanoparticles Fe3O4 and Fe3O4@SiO2 and Heterogeneous Fenton Catalytic Degradation of Methylene Blue

Dyestuff textile wastewater treatment has become a research hotspot due to its high chroma, poor biodegradability, and low toxicity characteristics. In this paper, we have synthesized magnetic Fe₃O₄ and core‐shell Fe₃O₄@SiO₂ materials by hydrothermal methods. These materials were characterized by XRD, TEM, N₂ adsorption‐desorption and so on. These materials’ heterogeneous Fenton has been applied to dye wastewater treatment. Methylene blue was used as a typical target of dye wastewater. Decolorization ratios of methylene blue were determined by different nanostructure composites catalysts. A serious of results of study showed that decolorization ratios of magnetic nanoparticles and core‐shell composites arrived at above 90 % under the weakly acidic or neutral conditions and room temperature. When these catalysts were reused, the results show that Fe₃O₄@SiO₂ materials were possessed with good cycle performance.     

Enhanced Photocatalytic Degradation of Synthetic Dyes and Industrial Dye Wastewater by Hydrothermally Synthesized G–CuO–Co<Subscript>3</Subscript>O<Subscript>4</Subscript> Hybrid Nanocomposites Under Visible Light Irradiation

To enhance the degradation of colour and chemical oxygen demand using photocatalytic activity, Graphene–CuO–Co₃O₄ hybrid nanocomposites were synthesized using an in situ surfactant free facile hydrothermal method. The photocatalytic degradation of synthetic anionic dyes, methyl orange (MO) and Congo red (CR), and industrial textile wastewater dyes under visible light irradiation was evaluated. The synthesized nanocomposite was characterized structurally and morphologically using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, high-resolution transmission electron microscope, and Fourier transform infrared spectroscopy. Evaluation of the colour indicated complete removal at 15 min of irradiation for the MO and CR dyes, with 99% degradation efficiency. The reaction time for the primary effluent wastewater dye was 60 min for 81% dye removal. In contrast, a longer reaction time was required to meet the national discharge regulation for the raw wastewater dye, 300 min for 60% dye removal. The mechanism for dye degradation using the Graphene–CuO–Co₃O₄ hybrid nanocomposite was elucidated using the Langmuir–Hinshelwood model, and the rate constant and half-life of the degradation process were calculated. The results demonstrate that photocatalytic degradation using a hybrid nanocomposite and visible light irradiation is a sustainable alternative technology for removing colour from wastewater dye.     

Enhanced dielectric performance and energy storage of PVDF‐HFP‐based composites induced by surface charged Al2O3

In order to enhance dielectric properties and energy storage density of poly(vinylidene fluoride‐hexafluoro propylene) (PVDF‐HFP), surface charged gas‐phase Al₂O₃ nanoparticles (GP‐Al₂O₃, with positive surface charges, ε’ ≈ 10) are selected as fillers to fabricate PVDF‐HFP‐based composites via simple physical blending and hot‐molding techniques. The results show that GP‐Al₂O₃ are dispersed homogeneously in the PVDF‐HFP matrix and the existence of nanoscale interface layer (matrix‐filler) is investigated by SAXS. The dielectric constant of the composites filled with 10 wt % GP‐Al₂O₃ is 100.5 at 1 Hz, which is 5.6 times higher than that of pure PVDF‐HFP. The maximum energy storage density of the composite is 4.06 J cm^?3 at an electrical field of 900 kV mm^?1 with GP‐Al₂O₃ content of 1 wt %. Experimental results show that GP‐Al₂O₃ could induce uniform fillers’ distribution and increase the concentration of electroactive β‐phase as well as enhance interfacial polarization in the matrix, which resulted in enhancements of dielectric constant and energy storage density of the PVDF‐HFP composites. This work demonstrates that surface charged inorganic‐oxide nanoparticles exhibit promising potential in fabricating ferroelectric polymer composites with relatively high dielectric constant and energy storage. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 574–583     

Photocatalytic activity of polyaniline/Fe-doped TiO2 composites by in situ polymerization method

This study was focused on the photocatalytic activity of polyaniline (Pani)/iron doped titanium dioxide (Fe–TiO₂) composites for the degradation of methylene blue as a model dye. TiO₂ nanoparticles were doped with iron ions (Fe) using the wet impregnation method and the doped nanoparticles were further combined with Pani via an in situ polymerization method. For comparison purposes, Pani composites were also synthesized in the presence undoped TiO₂. The photocatalyst and the composites were characterized by standard analytical techniques such as FTIR, XRD, SEM, EDX and UV–Vis spectroscopies. Fe–TiO₂ and its composites exhibited enhanced photocatalytic activity under ultraviolet light irradiation. Improved photocatalytic activity of Fe–TiO₂ was attributed to the dopant Fe ions hindering the recombination of the photoinduced charge carriers. Pani/Fe–TiO₂ composite with 30?wt.% of TiO₂ nanoparticles achieved 28% dye removal and the discoloration rate of methylene blue for the sample was 0.0025?min^?1. FTIR, XRD, SEM, EDX and UV–Vis spectroscopies supported the idea that Fe ions integrated into TiO₂ crystal structure and Pani composites were successfully synthesized in the presence of the photocatalyst nanoparticles. The novelty of this study was to investigate the photocatalytic activity of Pani composites, containing iron doped TiO₂ and to compare their results with that of Pani/TiO₂.     

Perylene polyphenylmethylsiloxanes for optoelectronic applications

The incorporation of fluorescent organic dyes in an encapsulating matrix represents a route to generate stable and processable materials for optoelectronic devices. Here, we present a method to embed perylene dyes into a high refractive index (HRI) polysiloxane matrix applying an allyl functionalized perylene dye and hydrosilylation chemistry. In a first approach, the dye molecules were covalently integrated into the backbone of linear polyphenylmethylsiloxane chains. The fluorescent and liquid polymers were synthesized with molecular weights from 5660 up to 8400 g mol^?1. In a second approach, the dye itself was used as a cross‐linking agent between linear polyphenylmethylsiloxane chains. These preformed fluorescent batch polymers are liquids with dye concentrations between 0.025 and 8 wt %. The applied synthetic methods incorporated the dye covalently into the polymer structure and avoided the crystallization of the dye molecules and thus the formation of excimers, which would reduce the optical emission. The resulting products can be easily incorporated into curable commercially available HRI polyphenylmethylsiloxane resins. The formed materials are ideal LED encapsulants with a solid and flexible consistency, a uniform dispersion of the dyes, and adjustable mechanical properties, realized by changing the amount of perylene polymers. Further properties of the obtained materials are thermal stabilities up to 478 °C, quantum yields larger than 0.97, and high photostabilities. Thus, the covalent integration of dyes into polyphenylsiloxane structures represents a possible route for the stabilization of the organic dyes against the extreme irradiance and thermal conditions in LED applications. © 2019 The Authors. Journal of Polymer Science Part B: Polymer Physics published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1062–1073     

Preparation of polymer electrolyte membranes based on poly(phenylene oxide) with different side chain lengths of phosphonic acid

A series of poly(phenylene oxide) (PPO) polymers bearing phosphonic acid groups on the methyl group and on the phenyl ring are synthesized as membrane materials for fuel cell applications. These phosphonic acid‐based PPO membranes exhibited high chemical resistance, dimensional stability, and good proton conductivity even under low humidity condition. Among the membranes, the one in which the phosphonic acid moiety is attached to the polymer main chain with ? CO(CH₂)₅? shows highest proton conductivity under overall conditions even though it has the lowest water uptake and IEC value. A well‐defined separation of the hydrophilic and hydrophobic phases suggests the phosphonic acid groups to form proton conduction channels via interchain hydrogen bonding. A high storage modulus of the membranes in various temperature ranges indicates that the membranes are suitable for use under a high temperature and low humidity conditions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019     

Dynamic mechanical and dielectric properties of ORMOCER® incorporating functionalized poly(styrene) latexes

Organically modified aluminosilicate hybrid materials incorporating polystyrene and poly(styrene‐co‐hydroxypropyl acrylate) latexes, (3‐glycidyloxypropyl) trimethoxysilane, and aluminum sec‐butoxide [Al(O^sBu)₃] were synthesized by a sol–gel process. The bulk materials obtained were macroscopically homogeneous dispersions with good mechanical properties. Dynamic mechanical and dielectric analyses of these new hybrid materials as a function of the Al(O^sBu)₃ concentration and copolymer composition revealed a series of transitions that represented relaxation processes of the incorporated polymer (glass transition), ?Al? O? Si?, the ?Si? O? Si? part of the network, and segmental motion of unreacted ?Si? (CH₂)₃OCH₂CHCH₂O chains. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 860–867, 2001     

Design and synthesis of optically transparent calcium‐incorporated polymer complexes

Transparent thin films of calcium‐ion‐incorporated polymer composites were synthesized with calcium carbonate (CaCO₃) and polymers such as poly(acrylic acid) (PAA), poly(ethylene glycol) (PEG), and methylcellulose. The homogeneous distribution of Ca²⁺ in the composite films was observed because of the high concentration of COO^? groups along the PAA backbone for the complexation of Ca²⁺ ions. The optical transparency of the composites depends on the weight percentages of the three polymers and the molar concentration of CaCO₃ in the composites. Maximum transparency was obtained for a composite film with a PAA/CaCO₃ ratio of 9:1. The results indicated that methylcellulose improved the film‐forming capabilities and that PEG improved the transparency of the composites. All polymer complexes were characterized with X‐ray diffraction, fourier transfer infrared spectroscopy, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, dynamic mechanical analysis, and optical transparency measurements. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4459–4465, 2004     

Preparation,characterization, and electrical properties of dual‐emissive Langmuir‐Blodgett films of some europium‐substituted polyoxometalates and a platinum polyyne polymer

A new series of organometallic/inorganic composite Langmuir‐Blodgett (LB) films consisting of a rigid‐rod polyplatinyne polymer coordinated with 2,7‐bis(buta‐1,3‐diynyl)‐9,9‐dihexylfluorene (denoted as PtP) as the π‐conjugated organometallic molecule, an europium‐substituted polyoxometalate (POM; POM = Na₉EuW₁₀O₃₆, K₁₃[Eu(SiW₁₁O₃₉)₂] and K₅[Eu(SiW₁₁O₃₉)(H₂O)₂]) as the inorganic component, and an amphiphilic behenic acid (BA) as the auxiliary film‐forming agent were prepared. Structural and photophysical characterization of these LB films were achieved by π–A isotherms, absorption and photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and low‐angle X‐ray diffraction. Our experimental results indicate that stable, well‐defined, and well‐organized Langmuir and LB films are formed in pure water and POM subphases, and the presence of Eu‐based POM in the subphase causes an area expansion. It is proposed that a lamellar layered structure exists for the PtP/BA/POM LB film in which the POM and PtP molecules can lay down with the interfacial planes. Luminescence spectra of the prepared hybrid LB films show that near‐white emission spectra can be obtained due to the dual‐emissive nature of the mixed PtP/POM blends. These Pt‐polyyne‐based LB films displayed interesting electric conductivity behavior. Among them, PtP/BA/POM 13‐layer films showed a good electrical response, with the tunneling current up to ±100 nA when the voltage was monitored between ?1 and 7 V. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 879–888, 2010     

The Hazardous Origin of Photocatalytic Activity of ZnCr2O4

The ZnCr₂O₄ catalysts are synthesized by thermal decomposition of (NH₄)₂[Zn(NH₃)₂(CrO₄)₂] and materials with high surface areas and particle sizes in the nano regime are obtained. A special structural feature of the materials are stacking faults with densities strongly depending on the synthesis temperature, i.e. the lower the temperature the larger the number of stacking faults. The catalyst prepared at the lowest decomposition temperature exhibiting the smallest particle size shows the highest catalytic activity in the photocatalytic degradation of y‐Eosin in a photo‐Fenton process. The results of different analytic methods demonstrate that the high catalytic activity is directly correlated with CrO₄^2– anions generated via photo‐oxidation of the catalyst. Therefore, ZnCr₂O₄ cannot be regarded as an environmental friendly catalyst for advanced photocatalytic oxidation processes.     

A mussel‐inspired method to fabricate a novel reduced graphene oxide/Bi12O17Cl2 composites membrane for catalytic degradation and oil/water separation

In this study, a novel dopamine modified graphene‐based photocatalytic membrane with Bi₁₂O₁₇Cl₂ inserted was fabricated to modify the commercial cellulose acetate membrane via vacuum filtration method. Results showed the reduced graphene oxide (RGO)/poly(dopamine) (PDA)/Bi₁₂O₁₇Cl₂‐CA photocatalytic composite membrane exhibited 98% removal efficiency for methylene blue (MB) within 100 minutes and 96% removal efficiency for 4‐CP within 160 minutes. Importantly, the photocatalytic composite membrane can simultaneously achieve dye degradation and oil‐water separation in only one device within a short time. And the as‐prepared membrane displayed great antifouling performance and recyclability after 10 cycles. Meanwhile, the membrane showed excellent stability in the agitated water bath or different pH conditions. In summary, the photocatalytic membrane investigated in this study opens new avenue for treatment of wastewater.     

Synthesis,characterization and photocatalytic application of TiO2/magnetic graphene for efficient photodegradation of crystal violet

A magnetized nano‐photocatalyst based on TiO₂/magnetic graphene was developed for efficient photodegradation of crystal violet (CV). Scanning electron microscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy and elemental mapping were used to characterize the prepared magnetic nano‐photocatalyst. The photocatalytic activity of the synthesized magnetic nano‐photocatalyst was evaluated using the decomposition of CV as a model organic pollutant under UV light irradiation. The obtained results showed that TiO₂/magnetic graphene exhibited much higher photocatalytic performance than bare TiO₂. Incorporation of graphene enhanced the activity of the prepared magnetic nano‐photocatalyst. TiO₂/magnetic graphene can be easily separated from an aqueous solution by applying an external magnetic field. Effects of pH, magnetized nano‐photocatalyst dosage, UV light irradiation time, H₂O₂ amount and initial concentration of dye on the photodegradation efficiency were evaluated and optimized. Efficient photodegradation (>98%) of the selected dye under optimized conditions using the synthesized nano‐photocatalyst under UV light irradiation was achieved in 25 min. The prepared magnetic nano‐photocatalyst can be used in a wide pH range (4–10) for degradation of CV. The effects of scavengers, namely methanol (OH^? scavenger), p‐benzoquinone (O₂^?? scavenger) and disodium ethylenediaminetetraacetate (hole scavenger), on CV photodegradation were investigated.     

Preparation of polymer optical fibers doped with nonlinear optical active organic chromophores

We synthesized two novel organic nonlinear optical chromophores—chiral S(+)‐N‐[p‐(4‐nitrostyryl) phenyl] prolinol and non‐chiral [p‐(4‐nitrostyryl) phenyl] piperdine—as potential laser‐active dyes for photonic applications. Both materials show good optical transmittance in the telecommunication frequency region, desirable solubility in acrylic polymer optical fiber matrices, and attractive fluorescence properties that are advantageous for laser‐gain materials and devices. Subsequently, these two chromophores were incorporated into poly(methyl methacrylate) and poly(ethyl methacrylate) and drawn into polymer optical fibers. The relevant properties of these organic dye‐doped fibers have been studied, revealing essential attributes of laser‐active characteristics. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1794–1801, 2001     

Photocatalytic and magnetic titanium dioxide/polystyrene/magnetite composite hybrid polymer particles

Novel multifunctional titanium dioxide (TiO₂)/polystyrene/magnetite composite hybrid polymer particle dispersions with TiO₂ nanoparticles in the surface and magnetite nanoparticles encapsulated inside the polymer matrix were produced by Pickering miniemulsion polymerization in one single step. Whereas TiO₂ nanoparticles were used to impart photocatalytic functionality and colloidal stability, magnetite nanoparticles were incorporated to allow an easy extraction for recovery and reuse of the composite multifunctional particles. The morphology of the composite particles was assessed by scanning transition electron microscopy (STEM) and energy‐dispersive X‐ray spectroscopy (EDX). The paramagnetism of the particles was analyzed using a SQUID magnetometer and their photocatalytic activity was assessed by degrading methylene blue (MB) solutions under UV light and by recovering and reusing of the particles in five consecutive cycles. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3350–3356     

BiOI负载MIL-101(Fe)@BiOI衍生BiFeO3@Fe2O3的增强光催化性能

采用溶剂热法合成了MIL-101(Fe)@BiOI复合材料,然后将其煅烧制备光催化性能增强的BiFeO₃@Fe₂O₃@BiOI三元复合材料。采用X射线衍射、扫描电镜、紫外可见漫反射吸收光谱等测试手段表征复合材料的组成、结构、形貌。将复合材料用于可见光照射下光催化降解四环素,研究复合比例(质量比)、pH和浓度对光催化性能的影响。电化学阻抗谱、光电流响应和莫特-肖特基曲线测试分析表明三元复合材料 BiFeO₃@Fe₂O₃@BiOI 表现出更强的光电流响应和更低的电荷转移电阻。当BiFeO₃、Fe₂O₃和BiOI三者理论质量比为1:1:1时,中性条件下降解活性最高,四环素去除率为81%。     

Eosin Y‐Functionalized Conjugated Organic Polymers for Visible‐Light‐Driven CO2 Reduction with H2O to CO with High Efficiency

Visible‐light‐driven photoreduction of CO₂ to energy‐rich chemicals in the presence of H₂O without any sacrifice reagent is of significance, but challenging. Herein, Eosin Y‐functionalized porous polymers (PEosinY‐N, N=1–3), with high surface areas up to 610 m² g^?1, are reported. They exhibit high activity for the photocatalytic reduction of CO₂ to CO in the presence of gaseous H₂O, without any photosensitizer or sacrifice reagent, and under visible‐light irradiation. Especially, PEosinY‐1 derived from coupling of Eosin Y with 1,4‐diethynylbenzene shows the best performance for the CO₂ photoreduction, affording CO as the sole carbonaceous product with a production rate of 33 μmol g^?1 h^?1 and a selectivity of 92 %. This work provides new insight for designing and fabricating photocatalytically active polymers with high efficiency for solar‐energy conversion.     

POM‐Catalyzed In Situ Ligand Synthesis for the Construction of Metal Complexes and Their Use in the Formation of Coordination Polymers

Six organic–inorganic hybrid materials were synthesized by the in situ oxidation of neocuproine by using MoO₃/Na₂MoO₄ as the catalyst in the presence of Cu(NO₃)₂. The crystal structures of Mo8‐Cu4‐PHEN and Mo8‐Cu2‐5(2PIC) are composed of [Mo₈O₂₆]^4? polyoxometalate (POM) units, whereas the crystal structure of Mo6‐Cu‐COPHEN is composed of a [Mo₆O₁₉]^2? POM unit; both POM units could be considered as the active form of the catalyst. Reaction of the hybrid materials with 1,3,5‐benzenetricarboxylic acid (BTC) resulted in the formation of two different coordination polymers (CPs) under different reaction conditions. These CPs, depending on their structural attributes, exhibit distinct differences in the adsorption of H₂, CO₂, and water. The use of 2‐methylpyridine instead of neocuproine does not give any oxidation products under the same reaction conditions due to the incorrect positioning of the methyl group with respect to the Cu^II center.