Characterization and enhancement in conductivity and conductivity stability of electropolymerized polypyrrole/Al2O3 nanocomposites

Co nanoparticles induced resistive switching and magnetism for the electrochemically deposited polypyrrole composite films

The resistive switching behavior of Co-nanoparticle-dispersed polypyrrole (PPy) composite films is studied. A novel design method for resistive random access memory (ReRAM) is proposed. The conducting polymer films with metal nanocrystal (NC)-dispersed carbon chains induce the spontaneous oxidization of the conducting polymer at the surface. The resistive switching behavior is achieved by an electric field controlling the oxygen ion mobility between the metal electrode and the conducting polymer film to realize the mutual transition between intrinsic conduction (low resistive state) and oxidized layer conduction (high resistive state). Furthermore, the formation process of intrinsic conductive paths can be effectively controlled in the conducting polymer ReRAM using metal NCs in films because the inner metal NCs induce electric field lines converging around them and the intensity of the electric field at the tip of NCs can greatly exceed that of the other region. Metal NCs can also bring new characteristics for ReRAM, such as magnetism by dispersing magnetic metal NCs in polymer, to obtain multifunctional electronic devices or meet some special purpose in future applications. Our works will enrich the application fields of the electromagnetic PPy composite films and present a novel material for ReRAM devices.

In situ Raman and UV-vis spectroscopic studies of polypyrrole and poly(pyrrole-2,6-dimethyl-β-cyclodextrin)

Polypyrrole (PPy) and poly(pyrrole-2,6-dimethyl-β-cyclodextrin) [P(Py-β-DMCD)] films prepared by potential cycling in aqueous acidic solutions on indium tin oxide (ITO)-coated glass and gold electrodes were studied by in situ UV-vis and Raman spectroscopy. Characteristic UV-vis and Raman bands were identified and their dependencies on the electrode potential have been discussed. Spectroelectrochemical results reveal differences both in the position of the spectral bands and their potential dependence for PPy and P(Py-β-DMCD) films indicating interactions between polymer chains and CDs during electropolymerization process. The films were also characterized by cyclic voltammetry and FT-IR spectroscopy.

Electrochemical quartz crystal impedance study on the overoxidation of polypyrrole–carbon nanotubes composite film for amperometric detection of dopamine

The electrochemical quartz crystal impedance (EQCI) method was used to study the overoxidation of polypyrrole (PPy)-multiwalled carbon nanotubes (MWCNT) nanocomposite film in neutral and alkaline solutions. The values of molar mass per electron transferred (M/n) obtained during the overoxidation of PPy in 0.10 mol L(-1) Na(2)SO(4) and 0.20 mol L(-1) NaOH aqueous solutions were estimated to be ca. 17 and 22 g mol(-1), respectively, suggesting the nucleophilic attack of solution OH(-) to the pyrrole units during the overoxidation, and the possible partial formation of carboxylic groups after the overoxidation in the NaOH solution. Also, the overoxidized PPy-MWCNT composite film prepared in the NaOH solution showed a notably larger affinity to dopamine (DA) dissolved in a neutral phosphate buffer than that prepared in the Na(2)SO(4) solution. The modification of the overoxidized nanocomposite film improved substantially the sensitivity for DA assay in a neutral phosphate buffer, as compared with the modification of overoxidized PPy or MWCNT alone. At a -6 kHz (201-nm thickness) nanocomposite film prepared in a polymerization bath containing 1.0 mg mL(-1) MWCNT and overoxidized in 0.20 mol L(-1) aqueous NaOH, the peak current response from differential pulse voltammetric assay of DA was linear with DA concentration from 4.0 x 10(-8) to 1.4 x 10(-6) mol L(-1), with a lower limit of detection of 1.7 nmol L(-1), good anti-interferent ability, as well as good stability and reproducibility.