Thermal stability of several polyaniline/rare earth oxide composites III

Polyaniline/Nd₂O₃ (PANI/Nd₂O₃) composites were synthesized by in situ polymerization at the presence of sulfosalicylic acid (as dopant). The composites obtained were characterized by Fourier transform infrared spectra (FTIR) and X-ray diffraction (XRD). The thermal stability of the composites was investigated by thermogravimetry (TG) and derivative thermogravimetry (DTG). The electrochemical performance of the composites was investigated by cyclic voltammetry (CV). The results of FTIR, XRD, and CV show that the structure of composite has changed greatly when Nd₂O₃ content is ≥0.7 g and the PANI in the composite has transformed into pernigraniline base (non-conducting state) from emeraldine base (conducting state). TG–DTG analysis indicates that the thermal stability of PANI/Nd₂O₃ composites was higher than the pure PANI.     

Effect Nd2O3 content on electrochemical performance of polyaniline/Nd2O3 composites

Polyaniline/neodymium(III) oxide (PANI/Nd₂O₃) composites were synthesized by in situ chemical oxidative polymerization method, and the new electrode materials were used for supercapacitor. The composites were characterized physically by scanning electron microscope (SEM), Fourier transform infrared spectra (FTIR) and X‐ray diffraction (XRD). SEM, IR and XRD results showed the existence of interactions between PANI and Nd₂O₃. The electrochemical capacitance performance of the composites was investigated by cyclic voltammetry, galvanostatic charge–discharge tests and ac impedance spectroscopy with a three‐electrode system in 6 M KOH solution. Cyclic voltammetry and galvanostatic charge/discharge tests proved that the addition of Nd₂O₃ enhanced the capacitance of the composites. However, the conductivity of the composites decreases with increasing the amount of Nd₂O₃. Electrochemical impedance tests manifest that the charge‐transfer resistance of the composites is smaller than that of the pure PANI, which indicates the addition of Nd₂O₃ could lower resistance and facilitate the charge transfer of the active materials. All results support that Nd₂O₃ has a significant contribution to the performance of PANI and makes the composites have more active sites for faradiac reaction and larger specific capacitance than pure PANI. Copyright © 2014 John Wiley & Sons, Ltd.     

Thermal stability of several polyaniline/rare earth oxide composites

Polyaniline/rare earth oxide composites (PANI/La₂O₃ and PANI/Sm₂O₃) were synthesized by in situ polymerization at the presence of sulfosalicylic acid (as dopant). The composites obtained were characterized by Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thermal stability of the composites was investigated by thermogravimetry (TG) and derivative thermogravimetry (DTG). The electrochemical performance of the composites was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results of FTIR, XRD, SEM, CV, and EIS show that the structure of composite has changed greatly when rare earth oxide content is >0.7 g (PANI/La₂O₃[w/w(92.7/7.3)] and PANI/Sm₂O₃[w/w(96.2/3.8)]) and the PANI in the composite has transformed into pernigraniline base (non-conducting state) from emeraldine base (conducting state). TG-DTG analysis indicates that the thermal stability of composite was higher than pure PANI, which is attributed to the interaction between PANI and rare earth oxide.     

Synthesis,characterization, thermal,electrical and magnetic properties of polyaniline composites with rare earth gadolinium coordination complex

Novel polyaniline/gadolinium (PANI/Gd) composites were successfully synthesized by “in‐situ” polymerization at the presence of rare earth Gd coordination complex and D‐tartaric acid (an a dopant). It is rarely to find the studies on related field to add rare earth Gd coordination complex as fillers. Fourier transform infrared (FTIR) spectra, X‐ray diffraction (XRD) and scanning electron microscope (SEM) were used to examine the structure and surface appearance characterization of materials. The thermal stability performance of composites was investigated by thermogravimetry and derivative thermogravimetry (TG‐DTG). Electrochemical performance was measured by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge test. The magnetic property was investigated by physical property measurement system (PPMS). The structure and surface appearance characterization and the magnetic properties jointly demonstrate the polymerization of rare earth Gd coordination complex and PANI–D‐tartrate (DTA) not only simple physical mixing but also chemical mixing. TG‐DTG analysis suggests that thermal stability of PANI/Gd composites is higher than that of PANI–DTA. Electrochemical performance tests and SEM indicate that the composite (PANI/Gd = 3.3:1,mass ratio) has the most regular morphology and best specific capacitance. The magnetization of the composite (PANI/Gd = 3.3:1,mass ratio)is evidently smaller compared with PANI–DTA and rare earth Gd coordination complex. Copyright © 2016 John Wiley & Sons, Ltd.     

Thermal stability and glass transition behavior of PANI/γ-Al2O3 composites

Polyaniline/γ-Al₂O₃ (PANI/γ-Al₂O₃) composites were synthesized by in-situ polymerization at the presence of HCl as dopant by adding γ-Al₂O₃ nanoparticles into aniline solution. The composites were characterized by FTIR and XRD. The thermogravimetry (TG) and modulated differential scanning calorimetry (MDSC) were used to study the thermal stability and glass transition temperature (T _g) of the composites, respectively. The results of FTIR showed that γ-Al₂O₃ nanoparticles connected with the PANI chains and affected the absorption characteristics of the composite through the interaction between PANI and nano-sized γ-Al₂O₃. And the results of XRD indicated that the peaks intensity of the PANI/γ-Al₂O₃ composite were weaker than that of the pure PANI. From TG and derivative thermogravimetry (DTG) curves, it was found that the pure PANI and the PANI/γ-Al₂O₃ composites were all one step degradation. And the PANI/γ-Al₂O₃ composites were more thermal stable than the pure PANI. The MDSC curves showed that the nano-sized γ-Al₂O₃ heightened the glass transition temperature (T _g) of PANI.     

Thermal stability and glass transition behavior of PANI/MWNT composites

Polyaniline/multi-walled carbon nanotube (PANI/MWNT) composites were prepared by in situ polymerization. Transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) were used to characterize the PANI/MWNT composites. Thermal stability and glass transition temperature (T _g) were measured by thermogravimetry (TG) and temperature modulated differential scanning calorimetry (TMDSC), respectively. The TG and derivative thermogravimetry (DTG) curves indicated that with augment of MWNTs content, the thermal stability of PANI/MWNT composites increased continuously. While, T _g increased and then decreased with the MWNTs content increasing from 0 to 20 mass%.     

Thermal behaviour of fumaric acid, sodium fumarate and its compounds with light trivalent lanthanides in air atmosphere

Characterization, thermal stability and thermal decomposition of light trivalent lanthanide fumarates, as well as, the thermal behaviour of fumaric acid and its sodium salt were investigated employing simultaneous thermogravimetry and differential thermal analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR), TG?CFTIR techniques, elemental analysis and complexometry. On heating, sublimation of fumaric acid is observed, while the thermal decomposition of the sodium fumarate occurs with the formation of a mixture of sodium carbonate and carbonaceous residue. The thermal decomposition of light trivalent lanthanide fumarates occurs in consecutive and/or overlapping steps with the formation of the respective oxides: CeO₂, Pr₆O₁₁, and Ln₂O₃ (Ln?=?La, Nd, Sm, Eu, Gd).     

Preparation,characterization and thermal decomposition of phenylenediammonium sulfate salts Part. XVI

Polyaniline/α-Al₂O₃ (PANI/α-Al₂O₃) composites were synthesized by in situ polymerization through ammonium persulfate ((NH₄)₂S₂O₈, APS) oxidized aniline using HCl as dopant. XRD and FTIR were used to characterize the PANI/α-Al₂O₃ composites. The thermal stabilities and glass transition temperature (T _g) of PANI/α-Al₂O₃ composites were tested using thermogravimetric (TG) method and modulated differential scanning calorimetry (MDSC) technique. The results of TG showed that the thermal stability of PANI/α-Al₂O₃ composite increased and then decreased with the increase in α-Al₂O₃ content. The derivative thermogravimetry (DTG) curves showed one step degradation of PANI when the α-Al₂O₃ content was lower than 52.5 mass%, and exhibited two steps degradation when the α-Al₂O₃ content was higher than 63.6 mass%. The MDSC curves showed that the T _g of PANI/α-Al₂O₃ composites increased and then decreased with the augment of α-Al₂O₃ for the interaction between PANI chains and the surface of α-Al₂O₃.     

Thermal stability of several polyaniline/rare earth oxide composites (I): polyaniline/CeO<Subscript>2</Subscript> composites

Polyaniline (PANI)/CeO₂ composites were prepared by adding CeO₂ powder into the polymerization reaction mixture of aniline. Fourier transform infrared spectra (FTIR) and X-ray diffraction (XRD) were used to characterize the composites. Thermogravimetry (TG) and derivative thermogravimetry (DTG) were used to study the thermal stability of the composites. IR and XRD results show that interaction exists between PANI and CeO₂. This interaction maybe is hydrogen bonding action between the hydroxyl groups on the surface of the CeO₂ and the imine groups in the PANI molecular chains. TG–DTG analysis indicates that the thermal stability of the composites is higher than that of the pure PANI. The improvement in the thermal stability of the composites is attributed to the interaction between PANI and CeO₂, which restricts the thermal motion of PANI chains and shields the degradation of PANI in the composites.     

One-step synthesis of PANI/Mn3O4 nanocomposites and evaluation of their electrochemical properties

In this paper, we have developed a simple, facile, and efficient approach to synthesize polyaniline/Mn₃O₄ (PANI/Mn₃O₄) nanocomposites using aniline as a reducer in the presence of KMnO₄ without any additives or templates. The morphology of the composites is characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results demonstrate that the tetrahedral Mn₃O₄ nanoparticles have uniform sizes and are finely dispersed in the PANI matrix. The crystallinity and chemical constituents of the composites are characterized by powder X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR) and UV-vis spectrophotometry. Moreover, cyclic voltammetry (CV) measurements are used to characterize the electrochemical properties of PANI/Mn₃O₄ nanocomposites. The developed materials give a pair of redox peaks and have better operation stability, which indicates that the composites show distinct electrochemical performance. So the PANI/Mn₃O₄ nanocomposites would have potential applications in bioanalysis, biodetection and so on.     

Synthesis,characterization and thermal analysis of polyaniline (PANI)/Co<Subscript>3</Subscript>O<Subscript>4</Subscript> composites

Conducting polyaniline/Cobaltosic oxide (PANI/Co₃O₄) composites were synthesized for the first time, by in situ deposition technique in the presence of hydrochloric acid (HCl) as a dopant by adding the fine grade powder (an average particle size of approximately 80 nm) of Co₃O₄ into the polymerization reaction mixture of aniline. The composites obtained were characterized by infrared spectra (IR) and X-ray diffraction (XRD). The composition and the thermal stability of the composites were investigated by TG-DTG. The results suggest that the thermal stability of the composites is higher than that of the pure PANI. The improvement in the thermal stability for the composites is attributed to the interaction between PANI and nano-Co₃O₄.     

Characterization and electrical transport properties of polyaniline and multiwall carbon nanotube composites

Polyaniline/multiwalled carbon nanotube (PANI/MWNT) composites were prepared by in situ polymerization. Scanning electron microscope, X‐ray diffraction, Fourier transform infrared, Uv‐Visible spectroscopy, Fluorescence spectrophotometry were done to characterize the PANI/MWNT composites. Thermal stability was measured by thermogravimetry analysis. The thermal stability of PANI/MWNT composites becomes higher than PANI. Electrical transport properties of different PANI/MWNT composites were investigated in the temperature range 77 ≤ T ≤ 300 K with and without magnetic field up to 1 T. The dc resistivity of PANI/MWNT composites shows different behavior compared to the sample without MWNT. The room temperature dc magnetoconductivity of the samples is negative; however, its sign changes to positive by lowering the temperature, which has been explained by hopping type charge transport. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1767–1775, 2010     

Thermal and spectroscopic studies of solid oxamate of light trivalent lanthanides

Solid-state LnL₃·1.25H₂O compounds, where L is oxamate and Ln is light trivalent lanthanides, have been synthesized. Simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC), experimental and theoretical infrared spectroscopy, TG–DSC coupled to FTIR, elemental analysis, complexometry, and X-ray powder diffractometry were used to characterize and to study the thermal behavior of these compounds. The results led to information about the composition, dehydration, thermal stability, thermal decomposition, and gaseous products evolved during the thermal decomposition of these compounds in dynamic air atmosphere. The dehydration occurs in a single step and through a slow process. The thermal decomposition of the anhydrous compounds occur in a single (Ce), two (Pr), and three (La, Nd to Gd) steps with the formation of the respective oxides, CeO₂, Pr₆O₁₁, and Ln₂O₃ (Ln = La, Nd to Gd). The theoretical and experimental spectroscopic study suggests that the carboxylate group and amide carbonyl group of oxamate are coordinate to the metals in a bidentate chelating mode.     

Nanostructured ferrite/graphene/polyaniline using for supercapacitor to enhance the capacitive behavior

Graphene nanosheets, polyaniline (PANI), and nanocrystallites of transition metal ferrite {Fe₃O₄ (Mag), NiFe₂O₄ (NiF), and CoFe₂O₄ (CoF)} have been prepared and characterized via XRD, FTIR, SEM, TEM, UV–vis spectroscopy, cyclic voltammetry, galvanostatic charge discharges, and impedance spectroscopy. Electrochemical measurements showed that supercapacitances of hybrid electrodes made of the ternary materials are higher than that of hybrid electrode made of binary or single material. The ternary hybrid CoF/graphene (G)/PANI electrode exhibits a highest specific capacitance reaching 1123 Fg^?1, an energy density of 240 Wh kg^?1 at 1 A g^?1, and a power density of 2680 Wkg^?1 at 1 A g^?1 and outstanding cycling performance, with 98.2% capacitance retained over 2000 cycles. The extraordinary electrochemical performance of the ternary CoF/G/PANI hybrid can be attributed to the synergistic effects of the individual components. The PANI conducting polymer enhances an electron transport. The Ferrite nanoparticles prevent the restocking of the carbon sheets and provide Faradaic processes to increase the total capacitance.     

One-step synthesis of polyaniline fibers with double-soft templates and evaluation of their doping process

In this paper, we have developed a simple, facile, and efficient approach to synthesize polyaniline fibers (PANI fibers) from aniline in the presence of (NH₄)₂S₂O₈ with sodium dodecyl benzene sulfonate (SDBS) and L-camphorsulfonic acid (L-CSA) as double templates. The chemical constituents of the composites are characterized by Fourier transformation infrared spectroscopy (FTIR). The results demonstrate that the PANI fibers were synthesized successfully. The morphology of the composites was characterized by scanning electron microscopy (SEM). The SEM and UV-Vis images show an interesting growth and doping process. Moreover, cyclic voltammetry (CV) was used to characterize the electrochemical properties of PANI microfibers. They also give a pair of redox peaks and have better operation stability, which indicates that the composites show distinct electrochemical performance. So the PANI microfibers would have potential applications in the fields of analytical chemistry, bioanalysis, etc.     

Preparation and electrochemical performance of the layered cobalt oxide (Co3O4) as supercapacitor electrode material

Layered Co₃O₄ composed of oriented self-assembled micrometer-length rectangular 2D flakes has been successfully synthesized by a hydrothermal method in combination with subsequent calcination process. Structural and morphological characterizations were performed using powder X-ray diffraction and field emission scanning electron microscopy. The component and thermal stability of the sample were measured by FT-IR and thermal analyses, including thermogravimetry and differential thermal analysis. The electrochemical performances of the as-prepared Co₃O₄ product were investigated by cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and constant current charge/discharge techniques. The electrochemical results demonstrate that the layered Co₃O₄ product displays good capacitive behavior with a specific capacitance of 263 F?g^?1 within a potential range of ?0.4–0.55 V at a current density of 1 A?g^?1 and a large capacity retention with 89.4 % of the initial capacitance over 1,000 consecutive cycles at 3 A?g^?1, indicating that the as-prepared Co₃O₄ product can be a promising electroactive material for supercapacitor.     

Tungsten oxide nanowires and polyaniline hybrid film-based electrochromic device with multicolor display and enhanced capacitance

Electrochromic devices (ECDs) have exhibited promising applications in the fields of energy-saving intelligent buildings and next-generation displays because of their simple structure, low power consumption, and multicolor displays. W₁₈O₄₉/polyaniline (PANI) hybrid films are prepared and assembled to ECDs. Compared with pure PANI and W₁₈O₄₉ films, the hybrid film exhibits superior electrochemical and electrochromic performance, including high optical modulation (70.2%), large areal capacity (79.6 mF/cm²), and good capacitance retention. The excellent electrochemical and electrochromic performance is ascribed to the formation of the donor (PANI)-acceptor (W₁₈O₄₉) pair, the porous structure in the nanowires, and the large surface area, which enhance electron delocalization of the W₁₈O₄₉/PANI, improve the ion diffusion rate, and increase the charge storage sites. Furthermore, benefitting from the outstanding optical, electrical, and multifunctional properties, the W₁₈O₄₉/PANI hybrid film-based ECD platform is expected to play an important role in electrochromism and energy storage.     

Preparation and electrochemical analysis of graphene/polyaniline composites prepared by aniline polymerization

Polyaniline (PANI)/graphene nanosheet (GNS) composites were prepared by a chemical oxidation polymerization. The morphology, structure, and crystallinity of the composites were examined by scanning electron microscopy, transition electron microscopy, and X-ray diffraction. Electrochemical properties were characterized by cyclic voltammetry in 1 M H₂SO₄ electrolyte. GNS are considered as supporting materials which can provide a large number of active sites. The PANI nanofibers with diameter of 50 nm were homogeneously coated on the surface of GNS. The PANI/GNS composites exhibited a better electrochemical performance than the pure individual components. The PANI/GNS composites showed the highest specific capacitance 923 Fg^?1 at 10 mVs^?1 compared to 465 Fg^?1 for pure PANI and 99 Fg^?1 for GNS.     

Electrical properties and EMI shielding behavior of highly thermally stable polyaniline/colloidal graphite composites

A hybrid approach has been adopted by using a combination of colloidal graphite (CG) as a conducting filler, 5‐lithium sulfoisophthalic (LiSIPA) acid as a dopant, and polyaniline (PANI) as a matrix to prepare LiSIPA doped PANI–CG composites. The thermal stability (～300°C) and electrical conductivity (67.4 S/cm at 17.4% CG content) have been improved significantly as compared to PANI doped with conventional inorganic dopants like HCl or H₂SO₄ (130–150°C). The maximum shielding effectiveness value was found to be ?39.7 dB. X‐ray diffraction and infrared spectroscopy showed a systematic shifting of the characteristic peaks and bands with increase in the amount of CG, which indicates significant interaction exists between CG and PANI. The UV–Vis spectra showed the characteristic bands of PANI, with a shift to shorter wavelength with increase in the CG content. The interaction mechanism between doped PANI and CG in the resultant composites has been proposed. Copyright © 2009 John Wiley & Sons, Ltd.     

Hydrothermal Self-assembly Synthesis of Mn3O4Reduced Graphene Oxide Hydrogel and Its High Electrochemical Performance for Supercapacitors

In the present work Mn3O4/reduced graphene oxide hydrogel （Mn3O4-rGOH） with three dimensional （3D） networks was fabricated by a hydrothermal self-assembly route. The morphology, composition, and microstructure of the as-obtained samples were characterized using powder X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, thermogravimetry analysis （TG）, atomic absorption spectrometry （AAS）, field emission scanning electron microscopy （FESEM） and transmission electron microscope （TEM）. Moreover, the electrochemical behaviors were evaluated by cyclic voltammogram （CV）, galvanostatic charge-discharge and electrochemical impedance spectroscopy （EIS）. The test results indicated that the hydrogel with 6.9% Mn3O4 achieved specific capacitance of 148 F.g^-1 at a specific current of 1 A.g^-1, and showed excellent cycling stabilily with no decay after 1200 cycles. In addition, its specific capacitance could retain 70% even at 20 A.g^- 1 in comparison with that at 1 A.g ^-1 and the operating window was up to 1.8 V in a neutral electrolyte.