Organically Soluble Bifunctional Polyaniline–Magnetite Composites for Sensing and Supercapacitor Applications

Abstract

Conducting polymers ͑CPs͒ now own a special status in the field of electroactive materials, especially after the pioneering and noble prize winning work by Shirakawa et al.1 A great deal of progress has been made on these synthetic metals in terms of their synthesis, processability, and device applications.2-4 Particular attention on polyaniline ͑PAni͒ has been given due to its environmental stability, thin-film-forming property with tunable conductivity and commercial viability. Polyanilines have been studied extensively due to their applications to practical devices for energy storage, electrochemical sensors, electrochromic devices, electromagnetic interference shielding, and corrosion protection.3-10 Application of the CPs in energy storage devices is also well known, 11 and recent studies 12 in this area gave impetus to fundamental and applied research on CPbased materials. Recent literature 13 identified the polyaniline composite materials as potential electrochemical sensors for various biomolecules.Applications of conducting polymers are broadened by compositing with other inorganic materials. For example, polyaniline-metal nanoparticle composites exhibit enhanced sensing and catalytic properties, compared to pure polyaniline. [14][15][16][17][18][19] Apart from the properties mentioned above, conducting polymers are useful as magneto/ electrorheological ͑ER͒ materials/fluids. 20-23 ER fluids is a class of materials whose rheological characteristics are controllable through the application of an electric field. ER fluids are usually made of particle suspensions with a large dielectric constant mismatch between the particles and the fluid. Because of the controllable rheological properties, ER fluids can potentially be used as a smart material for active devices, which transform electric energy to mechanical energy. Polyaniline can change its property from a conducting to an insulating state using simple protonic acid treatment. This allows for a change in dielectric constant and conductivity of particles while keeping all other particle properties the same.In the present communication, we report the synthesis of organically soluble bifunctional polyaniline-magnetite composites, which can sense dopamine and also act as supercapacitor electrode material. The results are presented and discussed. ExperimentalMaterials and methods.-Analytical grade aniline monomer was purchased from Merck, India. Dodecylbenzene sulfonicacid ͑70 wt % solution in 2-propanol͒ ͑DBSA͒ was purchased from Aldrich Chemical Company. Other characterization methods are similar to our earlier report. 12Synthesis of PAni-DBSA-Fe 3 O 4 nanocomposites.-Fe 3 O 4 magnetic particles were prepared by precipitation-oxidation method according to a known procedure, 24 according to which the size of the magnetite particles are in the range of 20-30 nm. PAni-magnetite composites were prepared by an in situ polymerization of aniline ͑1 mL͒ in DBSA ͑5 mL in 100 mL water͒ solution containing a specific amount of Fe 3 O 4 magnetic particles according to...

Effect of Ni, Cr, V, and Zn Substitution on the Electrochemical Properties of Spinel Ferrites

“…The crystal structure of spinel ferrites includes metal ion sites in the gaps of a cubic close‐packed oxygen lattice, namely, 8a oxygen tetrahedral sites and 16d oxygen hexahedral sites. When these sites are occupied by transition metal ions, the occupancy ratio does not agree with the composition ratio: instead, the occupancy ratio is known to be determined by the crystal field stabilization energy with regard to crystal field splitting of the 3d orbital . Therefore, in spinel ferrites, Zn 2 + and V 5 + have a strong preference for oxygen tetrahedral 8a sites, while Ni 2 + and Cr 3 + have a strong preference for 16d sites.…”

“…As regards the latter, there are reports of high pseudocapacitance achieved by using RuO 2 electrodes [1,2]. However, ruthenium is very expensive, and new alternative materials are being considered [3][4][5][6][7][8][9][10][11][12][13]. In particular, inexpensive iron oxides are attracting much attention.…”

Significantly enhanced energy density of magnetite/polypyrrole nanocomposite capacitors at high rates by low magnetic fields

“…As shown in Fig. 2a, at the case of 200 mV/s without the magnetic field, the pure PPy exhibits Faradic currents without obvious redox peaks in the potential range from − 0.2 to 0.8 V, whereas a pair of redox peaks (oxidation peak BI^at around 0.5 V in the positive scan and the reduction peak BI′^at around 0.3 V in the negative scan) associated with the magnetite nanoparticles [45] is observed in the nanocomposites; the peak current density becomes much higher with increasing the nanoparticle loading. A positive shift from 0.46 to 0.52 V in the oxidation peak and a negative shift from 0.36 to 0.31 V in the corresponding reduction peak are also noted with increasing the nanoparticle loading from 20.0 to 40.0 wt%.…”

An Industry Friendly Approach for the Preparation of Magnetic and Electro-Conductive Polyaniline Composite Particles

“…X-ray diffraction (XRD) studies on the composites reveal the inclusion of Fe 3 O 4 particles in the composites [17]. Fig.…”