Polypyrrole Ppy Research Articles

Structural Morphology and Optical Properties of Nanocomposites based Conducting Polymer

A simple, inexpensive, pulsed laser deposition (PLD) technique excimer source Nd:YAG laser was used for the preparation of the all films irradiation targets and deposite of nickel oxide NiO, polypyrrole PPy, carboxylic functionalized multi-walled carbon nanotubes (f-MWCNT), [PPy:(f-MWCNT)] nanocomposite, [NiO/PPy:(f-MWCNT)] and [PPy:(f-MWCNT)/NiO] films on fluorine-doped tin oxide (FTO) substrates. Surface morphology of all films and nanocomposite was investigated by Scanning Electron microscopy (SEM) display various morphology on the surface of the all films and nanocomposites, but the predominant structure is granular morphology, x-ray diffraction (XRD) indicates that the peaks of all films are broadening expect for PPy are sharp peaks, the optical absorbance spectra for the studied all films showed the maximum values around (425, 333, 347, and 397) nm refer to type transitions (π*-π) and (polaron-π*) and the maximum value of NiO around 346 nm. The optical energy gap of all films was determined and values around (2.2, 2.6, 2.8, 3, 3.2) eV. It has been observed that the measurements for films [NiO/PPy:(f- MWCNT)] and [PPy:(f-MWCNT)/NiO] may be identical and NiO nanoparticles are a good adhesion to nanocomposite films and interconnected in structure.

Preparation of LiFePO4 added PPy as cathode materials for li-ion battery

LiFePO4 is an alternative cathode material for lithium-based battery cells. LiFePO4 demonstrates many advantages such as non-toxicity, low cost, and stable structure. One of the main problems of LiFePO4 is its low electronic conductivity, which results in its poor rate capability due to the poor kinetics of lithium intercalation/deintercalation process. The objective of this study is to increase the electrical conductivity of LiFePO4. An in-situ carbon source such as polypyrrole PPy was applied to prepare LiFePO4/C composites by heat treatment. The nature of polypyrole in the system can be considered not only as carbon source, but also as a structure director. The LiFePO4/C composites were prepared with the addition of PPy which were varied between 2.5, 5, 7.5, 10 and 15 % weight, and graphite also added in the amount of four times the PPy content. The crystal structure, surface morphology, elemental analysis, and conductivity of LiFePO4/C composites were characterized by X-ray diffraction and scanning electron microscopy combined with energy dispersive spectrometry and use of LCR meter, respectively. The XRD patterns of LiFePO4/C composites showed that the LiFePO4/C particles belong to a pure orthorhombic system of olivine-type structure (Pnma, JCPDS: 40-1499). Carbon phase was not found apparently from the XRD pattern, which indicated that it may be present in amorphous form. The particles morphology were composed of primary particles approximately 400 nm in diameter, with homogeneous pores and were agglomerated, while carbon deposition was observed on the surface. The addition of PPy increased the conductivity of materials. The highest conductivity of LiFePO4/C composite was 9.74 × 10−2 S cm−1 reached by the addition of 15% PPy.

Synthesis and spectroscopic characterization of polypyrrole PPy coating on flax fibers and its behaviour toward trimethylamine vapor

This work aims to elaborate PPy-flax composite via chemical in-situ polymerization of pyrrole on flax fiber in aqueous medium. The flax-PPy gas sensor was examined for trimethylamine gases. It was found that the electrical resistance of PPy coating increases in the presence of organic vapors while it decreases in clean air. The results of this study show the high efficiency of flax-PPy sensor toward toxic vapors. The influence of input parameters such as gas concentration has also been investigated. The synthesized sensor was characterized by different techniques such as X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM).

OXYGEN REDUCTION ON Cu1 ,Mn16O4 SPINEL PARTICLES COMPOSITE ELECTRODES EFFECT OF PARTICLES SIZE

ABSTRACT The oxygen reduction reaction (orr) was studied on CG/PPy/PPy(Ox)/PPy and CG/paint/CC(Ox)PPy composite electrodes, CG representing conducting glass, PPy polypyrrole, CC carbon cloth and Ox mixed valence spinel oxide particles of transition metals Cu 1.4 Mn 1.6 O 4 in 0.2 M KCl pH = 9.2, at room temperature. PPy is electrochemically polymerized and serves as a protective layer to dispersed oxide particles in the carbon cloth. Oxide particles size varied from 7.6 to 11.2 µm. The orr takes place on the oxide particles with formation of hydrogen peroxide which diffuses to electrolyte solution. The amount of peroxide ions produced was detected using the rotating ring-disk electrode technique and determined indirectly by iodine spectroscopy. The peroxide ions production depends strongly on the oxide particle size. Keywords: Copper manganites, Spinel oxide, Composite electrode, Polypyrrole, Oxygen electroreduction. INTRODUCTION The importance of the cathodic oxygen reduction reaction (orr) to water either directly or indirectly via hydrogen peroxide is widely recognized due to their applications such as oxygen electrode in fuel cells, lithium-air batteries, wastewater treatments and, organic and inorganic synthesis. In fuel cells the orr is the only employed reaction to accept electrons from chemicals such as methanol, ethanol or other molecules

Oxygen reduction on high-area carbon cloth-supported oxide nanoparticles/polypyrrole composite electrodes

Composite electrodes on glassy carbon (GC) having the structure GC/CC(Ox)/PPy, with CC representing carbon cloth, PPy polypyrrole and Ox mixed valence spinel oxide nanoparticles of transition metals Cu 1.4Mn 1.6O 4, exhibit high reactivity and stability towards the oxygen reduction reaction (ORR), when the ORR proceeds electrocatalytically on the oxide particles dispersed throughout the carbon cloth. PPy here is electrochemically polymerized and serves as a protective layer to make the oxide sandwiched between PPy and CC fiber backbone. In oxygen saturated 0.15 M KCl solution, the composite electrodes show a good performance with current density up to 10 mA cm − 2 under gentle stirring. The enhancements of the composite electrodes for ORR result from the oxide nanoparticles dispersed on high-area CC. Optimal oxide loadings were encountered at 3.5 mg cm − 2 .

Evidence for Metal-like Electronic Contribution in Low-Temperature Heat Capacity of Polypyrrole

Heat capacity measurements in the temperature range of 0.6 to 12 K have been conducted on doped polypyrrole films. At low temperature, a finite electronic contribution gamma prevails in all samples. The value of gamma for hexafluorophosphate doped polypyrrole PPy(PF6) is 6.31 mJ x K(-2) x mol(-1), but is 2.2 mJ x K(-2) x mol(-1) for p-toluene sulfonate doped polypyrrole PPy(TsO). With use of the free electron model, the corresponding densities of states at the Fermi level N(E(F)) are calculated and compared with those obtained from spin susceptibility data.

Modification of intrinsically conducting polymers by ion implantation

The ion beam modification of polymers has attracted many groups in the past. However, only little attention has been paid to the ion bombardment effects in intrinsically conducting polymers like polyacetylene or polypyrrole PPY. We studied PPY earlier and found that ion bombardment leads to a loss of conductivity because of structural changes of the polymer. The loss of conductivity causes interesting secondary effects investigated in the present paper. By implanting through masks or with focused ion beams it is possible to obtain lateral structured conducting polymers. The structures can be developed in 3-dimensional patterns by electrochemical treatment and by galvanic metal deposition. The resulting structures were vizualized using scanning force microscopy. In addition the catalytic effect of platinum deposition on the electrochemical dissolution of PPY was studied. The results bear interesting consequences for future applications.