Bowl-shaped poly(3,4-ethylenedioxythiophene)/γ-Fe2O3 composites with elecromagnetic function

In this paper, electromagnetic poly(3,4-ethylenedioxythiophene)/γ-Fe2O3 (PEDOT/γ-Fe2O3 ) micro-bowls, 1 2 μm in diameter, were prepared by a simple environment-friendly process. In this method, the aqueous solution of cetyltrimethylammonium bromide (CTAB) instead of any organic solvent was used. FeCl3 acted as a source of Fe Ⅲ for the formation of γ-Fe2O3 and as an oxidant for the polymerization of 3,4-ethylenedioxythiophene (EDOT). The bowl-shaped morphology of PEDOT/γ-Fe2O3 composites was strongly influenced by the concentration of CTAB, FeCl2 , ammonia solution and the reaction temperature. The saturation magnetization of PEDOT/γ-Fe2O3 micro-bowls increased with the increase of FeCl2 concentration and reached 6.20 Am2 /kg at the FeCl2 concentration of 0.30 mol/L. The conductivity of the PEDOT/γ-Fe2O3 composites was in the range of 101 S/cm. The electrical and magnetic sources of PEDOT/γ-Fe2O3 micro-bowls were confirmed by SEM-EDX, TEM, XRD and XPS spectra. And the possible formation mechanism of PEDOT//γ-Fe2O3 was proposed.     

Characterisation of the aluminium–electropolymerised poly(3,4-ethylenedioxythiophene) system

Poly(3,4-ethylenedioxythiophene) (PEDOT) was electropolymerised on aluminium substrates. The Al/Al oxide/PEDOT junction was studied by electrochemical impedance spectroscopy, comparing the impedance response of the polymer film in oxidised, neutral and reduced form. The p- and n-doping behaviour of the PEDOT films was studied by in situ external reflection Fourier transform infrared spectroscopy during stepwise potential cycling of the films. The Al surface underneath the polymer was analysed with X-ray photoelectron spectroscopy. The impedance spectra indicate that an insulating layer between the metal and the polymer grows thicker during doping of the polymer film. The other techniques used suggest that this interfacial layer consists mainly of Al oxides and fluorides. Neither the conductivity nor the dopability of the polymer is notably affected by the growing of this insulating interfacial layer, which makes the concept of PEDOT electropolymerised on Al promising from an organic electronics applications point of view.     

Sol–gel synthesis of Mn2O3/Al2O3/SiO2 hybrid nanocomposite and application for removal of organic dye

Journal of Sol-Gel Science and Technology - Nanocomposite of Mn2O3/Al2O3/SiO2 was prepared through an in situ sol–gel process, in which Mn2O3 nanocrystals were dispersed in the silica-alumina...     

Optimizing incorporation of nickel(II)–cyclam complex in poly(3,4-ethylenedioxythiophene) films for catalytic purposes

Poly(3,4-ethylenedioxythiopene) (PEDOT) films, due to their porous and open structure, as well as high stability, were chosen as a membrane for incorporation of Ni(II) ion complexes with 1,4,8,11-tetraazacyclotetradecane (cyclam) or deposition of electroactive films containing polymerized complex. Accumulation of the complex in PEDOT layers and its electrocatalytic activity was studied basing on voltammetric behavior of Ni(II)–cyclam and electroxidation of a model reactant-methanol in alkaline solutions. Several modes of complex incorporation were tested, based on open circuit conditioning or polarization in the presence of nickel ions and cyclam. It was found that the most effective method was incorporation of cyclam in the course of PEDOT electrosynthesis, followed by potentiostatic accumulation of Ni(II) ions. This procedure resulted in around 50 times higher slope of dependence of methanol oxidation current on alcohol concentration than in the absence of PEDOT.

     

Hybrid organic–inorganic nanocomposite materials for application in solid state electrochemical supercapacitors

Integration into a conducting polymer matrix to form a hybrid material is an effective way to harness the electrochemical activity of nanosized oxide clusters. By anchoring them into polyaniline, the reversible redox chemistry of the otherwise soluble polyoxometalate clusters can be combined with that of the conducting polymer and be put to work in energy storage applications. We present here preliminary results that show how the resulting hybrid polymer displays the combined activity of its organic and inorganic components to store and release charge in a solid state electrochemical capacitor device.     

Preparation and characterization of poly(2′-aminomethyl-3,4-ethylenedioxythiophene) by chemical oxidative polymerization

Poly(2′-aminomethyl-3,4-ethylenedioxythiophene) was synthesized by the chemical oxidative polymerization of 2′-aminomethyl-3,4-ethylenedioxythiophene in the presence of different oxidants, such as FeCl₃, Ce(SO₄)₂, (NH₄)₂Ce(NO₃)₆, and (NH₄)₂S₂O₈. The as-formed polymer was investigated by FTIR, UV–Vis, and Raman spectroscopy, fluorescence, thermogravimetry, and X-ray diffraction to determine the structure, photophysical properties, thermal stability, and polymer phase. FTIR and Raman spectra measurements indicated that the formation of macromolecules occurred exclusively via α,α-coupling of thiophene rings. Moreover, polymer obtained in polymerization using Ce(SO₄)₂ as the oxidant displayed superior thermal stability. All the characterizations indicated that FeCl₃ was the more suitable oxidant for oxidative polymerization of the monomer and provided formation of polymer with higher yield.     

Microwave-assisted sol-gel synthesis of CeO2–NiO nanocomposite based NO2 gas sensor for selective detection at lower operating temperature

The progress in the development of gas sensors has considerably grown using some novel nanomaterials of metal, metal oxide and composite. In the current study, we intended and evaluated the properties of nanomaterials like CeO₂, NiO, and CeO₂–NiO composite and its application as NO₂ gas sensor. Sensing of low concentration of NO₂ gas at optimum functional temperature was succeeded using CeO₂–NiO nanocomposites (NCs) film. The working temperature ranges in between 100 and 225 ?°C. Highly crystalline nanomaterials (CeO₂, NiO and CeO₂–NiO) have been prepared by applying microwave-assisted sol-gel route. The as-prepared nanomaterials are characterized for their structure, size, morphology and constitution by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis. XRD studies of nanoparticles reveal the formation of nanoscale CeO₂ and NiO with crystallite size 26, 23 ?nm, respectively. Both are having a face centered cubic structure. The nanocomposite (NC) Ce:Ni ?= ?60:40 has crystallite size of 13 ?nm. XRD study of NCs shows assimilation of Ni metal into the ceria and proves physical similarities of two phases. It can be observed from SEM that prepared NC has a porous surface which enables more surface active sites for adsorbing oxygen. The optical properties are measured with the help of UV–Vis. Spectroscopy. Optical band gaps of 3.19, 3.41 and 2.9 ?eV were observed for CeO_2, NiO nanoparticles (NPs) and CeO₂–NiO NC, respectively. Gas sensing properties state that the NC material shows a higher gas response % of 67.34% for NO₂ gas (25 ?ppm) at comparatively low operating temperature (125 ?°C). It gives response time as (～28 ?s) and the recovery (～54 ?s). NiO incorporation in CeO₂ results in a decline of operating temperature of NC and improves the sensing features.     

Thermodynamics of BaCa(1 + y)/3Nb(2 − y)/3O3 − δ·xH2O proton-conducting perovskites

Journal of Thermal Analysis and Calorimetry - Complex perovskites BaCa(1?+?y)/3Nb(2???y)/3O3???δ (y?=?0, 0.18 and 0.5) with...     

Optimizing incorporation of nickel(II)�Ccyclam complex in poly(3,4-ethylenedioxythiophene) films for catalytic purposes

Poly(3,4-ethylenedioxythiopene) (PEDOT) films, due to their porous and open structure, as well as high stability, were chosen as a membrane for incorporation of Ni(II) ion complexes with 1,4,8,11-tetraazacyclotetradecane (cyclam) or deposition of electroactive films containing polymerized complex. Accumulation of the complex in PEDOT layers and its electrocatalytic activity was studied basing on voltammetric behavior of Ni(II)?Ccyclam and electroxidation of a model reactant-methanol in alkaline solutions. Several modes of complex incorporation were tested, based on open circuit conditioning or polarization in the presence of nickel ions and cyclam. It was found that the most effective method was incorporation of cyclam in the course of PEDOT electrosynthesis, followed by potentiostatic accumulation of Ni(II) ions. This procedure resulted in around 50 times higher slope of dependence of methanol oxidation current on alcohol concentration than in the absence of PEDOT.     

Study on poly(3,4-ethylenedioxythiophene) behaviour in the I−/I2 solution

The properties of poly(3,4-ethylenedioxythiophene) (PEDT) film have been studied in iodide solutions by cyclic voltammetry and stripping voltammetry methods. It has been shown that formation of charge-transfer complexes between iodine species and polymeric rings promotes storage of iodine on an electrode covered by PEDT film. Due to this behaviour the PEDT layer can be employed for electroanalysis of dilute (10⁻⁴–10⁻³ M) solutions of iodide salts by stripping voltammetry methods. The possibility of PEDT film application for zinc-iodide rechargeable batteries was also examined.     

One-pot sonochemical synthesis of superhydrophobic organic–inorganic hybrid coatings on cotton cellulose

Inspired by the surface structure of lotus leaves, different types of superhydrophobic cellulosic materials with contact angle (CA) of higher than 150° are currently provided. However, fabrication of these surfaces in a facile one-step coating process is one of the challenging issues. This paper describes a facile method to sonochemically synthesize superhydrophobic organic–inorganic hybrid coatings on cotton fabric by an alkaline-catalyzed co-hydrolysis and co-condensation of tetraethylorthosilicate and alkyltrialkoxysilanes. The influence of alkyl chain length (methyl, octyl, hexadecyl) of silane and reaction time was investigated. Surface structure of the fabrics was investigated by SEM, EDS, FTIR spectroscopies, and reflectance spectrophotometry. Wettability properties were studied by measuring water CA, shedding angle (SHA) and resistance to wetting by a series of ethanol–water mixtures of different surface tensions. The results showed that the treated fabrics were coated with a homogeneous thin nano-scaled coating of hybrid silica nano-particles. The fabrics demonstrated CA of higher than 150°, SHA in the range of 6–24° and different stickiness to water droplets. The fabrics treated by silanes with longer alkyl chain length and at higher reaction time revealed better water repellency. The coatings were nearly transparent, could not affect the color of the fabrics and had high stability against repeated washing. In addition, mechanical properties of the fabrics were not substantially affected.     

Synthesis and characterization of new hybrid inorganic–organic polymer nanocomposite as efficient catalyst for oxidative desulfurization of real fuel

Sulfur-containing compounds are responsible for much air pollution, and therefore eliminating these compounds is of importance. Herein, a hybrid organic–inorganic recyclable nanocatalyst (TBA-PW₁₁Ni@PANI) was synthesized successfully to investigate its effects on the catalytic oxidative desulfurization (CODS) process of real gasoline/model fuel. To this end, the Keggin-based mono-lacunary polyoxometalate [PW₁₁NiO₃₉] was prepared and modified with quaternary cation tetrabutylammonium (TBA). Then, this was further immobilized on polyaniline (PANI) via the sol–gel method. The synthesized nanocomposite was characterized using various techniques. The high dispersion of polyoxometalate on PANI was confirmed. Also, it was found that the crystalline structure remained unaltered after immobilization. In addition, the effects of various parameters such as dosage and temperature on the CODS of model fuel in the presence of H₂O₂–acetic acid (1:2 v/v) were studied in detail. Moreover, the kinetics of the CODS process was also studied and a mechanism proposed. According to the results, TBA-PW₁₁Ni@PANI showed an efficiency of up to 97% with 0.1 g at 35°C (optimum values) which implies its good catalytic functionality in the CODS process. Finally, the TBA-PW₁₁Ni@PANI catalyst displayed long-term stability and good reusability after five runs.     

Hydrothermal synthesis and structural characterization of two inorganic–organic composite sandwich-type tungstogermanates

Two new inorganic–organic hybrid polyoxotungstates [enH₂][C₈N₄H₂₂]₃H₂[Co₄(enH)₂(GeW₉O₃₄)₂] · 6H₂O (1) and [Co(en)₃]₂H₆[Co₄(enH)₂(GeW₉O₃₄)₂] · 14H₂O (2) (en = ethylenediamine) have been synthesized by hydrothermal methods and characterized by IR, TG, XRD, XPS, elemental analysis, and single-crystal X-ray analysis. The polyoxoanion frameworks of the two compounds consist of two classical tetra-Co sandwiched polyoxoanions [Co₄(H₂O)₂(GeW₉O₃₄)₂] in which two organic ligands substitute two water molecules. The tetra-Co clusters in 1 and 2 exhibit the familiar structural type of a β-junction at the sites of metal incorporation. Compound 1 is of interest owing to its C₈N₄H₂₀ ligands resulting from the reaggregation of triethylenetetramine which occurs under 160°C.     

Electrocatalytic performance of poly(o-phenylenediamine)-Pt–Ru nanocomposite for methanol oxidation

The electrocatalytic properties of poly(o-phenylenediamine) (PoPD)-Pt–Ru nanocomposite electrode for methanol oxidation have been investigated by linear sweep and cyclic voltammetry. The Pt–Ru ion concentration ratio in the electrodeposition bath is varied in the ratios of 1:0.25, 1:0.5, 1:1, 1:2, and 1:4. The morphology and particle size of the nanocomposites are obtained from the scanning electron microscopy data. The onset potential for the oxidation of methanol is found to be effectively reduced by 220 mV for the (PoPD)-Pt–Ru (1:1) nanocomposite compared to PoPD-Pt electrode. Also, the PoPD-Pt–Ru (1:1) composite shows a value of 4.2 for the ratio of forward to reverse peak current which is relatively a high value that can be observed among the conducting polymer-based catalysts used for methanol oxidation. The results are substantiated by the polarization and stability data.     

Hydrothermal synthesis and structure characterization of a new organic–inorganic composite (4,4′-H2bipy)2(4,4′-hbipy)2(ZnW12O40)·6H2O

A new organic–inorganic composite (4,4′-H₂bipy)₂(4,4′-Hbipy)₂(ZnW₁₂O₄₀)·6H₂O has been prepared by hydrothermal reaction and characterized by elemental analysis, IR and UV spectra, thermal analysis and single-crystal X-ray structural analysis. It belongs to the monoclinic system, space group P2₁/c, with a?=?18.637(4), b?=?14.003(3), c?=?26.470(5)?Å, β?=?104.78(3)°, V?=?6680(2)?ų, Z?=?4. Structural analysis indicates that the title complex consists of a Keggin anion [ZnW₁₂O₄₀]^6?, 4,4′-bipyridine and water of crystallization, constructing a supramolecular system through hydrogen bonding interactions. Thermal analysis shows that the heteropolyanion [ZnW₁₂O₄₀]^6? starts to decompose at 587.0°C.     

UV-light and visible-light photochromism of inorganic–organic multilayer films based on polyoxometalate and poly(acrylamide)

Novel UV-light and visible-light photochromic inorganic–organic multilayers composed of polyoxometalates (phosphomolybdic acid (PMoA)) and poly(acrylamide) (PAM) were prepared by the layer-by-layer (LbL) self-assembly method. The grown process, composition, surface topography, and photochromic properties and mechanism of the multilayer films were investigated by ultraviolet–visible (UV–vis) spectra, Fourier transform infrared spectra (FT-IR), atomic force microscopy (AFM), electron resonance spectra (ESR), and X-ray photoelectron spectra (XPS). Irradiation with UV-light or visible-light, the transparent films changed from colorless to blue and showed reversible photochromism. PMoA/PAM LbL films had higher photochromic efficiency under UV-light irradiation than visible-light irradiation. The bleaching process occurred when the films were in contact with O₂ in the dark or heated in air. The photochromic process of PMoA/PAM LbL film was in accordance with radical mechanism.     

Synthesis and characterization of organic–inorganic macrocyclic molecular brushes with poly(ε-caprolactone) side chains

In this work, we reported the synthesis of a dodecahydroxyl-functionalized macrocyclic oligomeric silsesquioxane (MOSS). The novel 24-membered hydroxyl-functionalized MOSS was employed as a macroinitiator for the ring-opening polymerization of ε-caprolactone (CL) and the organic–inorganic macrocyclic molecular brushes with poly(ε-caprolactone) (PCL) side chains were successfully synthesized. The organic–inorganic macrocyclic molecular brushes were characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). The results of wide angle X-ray diffraction (XRD) indicate that the architecture of the organic–inorganic macrocyclic molecular brushes did not alter the structure of PCL crystals. Differential scanning calorimetry (DSC) shows that the architecture of organic–inorganic macrocyclic molecular brushes significantly affected the rearrangement of PCL crystals. Compared to linear PCL, the organic–inorganic macrocyclic molecular brushes possessed the improved thermal stability in terms of the temperatures at the maximum of degradation rate and the yields of degradation residues.     

Superparamagnetic Fe3O4@Alginate supported L-arginine as a powerful hybrid inorganic–organic nanocatalyst for the one-pot synthesis of pyrazole derivatives

Hybrid inorganic–organic material Fe₃O₄@Alg@CPTMS@Arg, was prepared by the layer-by-layer techniques through grafting l-arginine (l-arg) to Fe₃O₄@Alg using 3-chloropropyltrimethoxysilane (CPTMS) as a linker. Fe₃O₄@Alg was prepared by in situ co-precipitation of iron (iii) and iron (ii) chloride in the presence alginate (Alg). The hybrid inorganic–organic material was characterized employing various techniques such as Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). The as-prepared Fe₃O₄@Alg@CPTMS@Arg nanoparticles mediated the synthesis of pyrazole derivatives with via one-pot reaction between phenylhydrazine, malononitrile, and various aromatic aldehydes under reflux in ethanol. Recycled catalyst exhibited comparable efficacy after seven cycles. The high catalytic activity, excellent yields, as well as the recyclability of the hybrid nanomaterials with quantitative efficiency, are factors that render this environmentally benign procedure appealing.