Search

Abstract: One-dimensional growth of polyaniline (PANI) was conducted on carbon cloth through a pulse potentiostatic method. Hydrolysis of PANI was depressed, and the generated PANI film (PPM) displayed improved electroactivities. The specific capacitance of PPM was increased by 39% when compared to that of PANI film made by the conventional potentiostatic method (PM). The influences of the upper limit potential of the pulse potentiometry and the acidity of the polymerization solution on surface morphologies, electroactivities and conformation of the PANI films were studied by SEM, cyclic voltammetry, chronopotentiometry and UV–Vis spectrometry. [Copyright &y& Elsevier]

Abstract: Humidity sensor based on polyaniline nanofibres was fabricated and its response to humidity was investigated. It was found that the sensor behaved differently compared to commonly known conducting polymer based sensors. The sensor responded to low relative humidity (<50% RH) normally by decreasing electrical resistance with increasing humidity. However, at higher RH the sensor reversed its responses by increasing the electrical resistance with humidity. It is believed that the unique structure of nanofibres, which is more susceptible to distortion during polymer swelling, is responsible for the ‘reversed behaviour’. IR data confirmed that excess water absorption occurred and that a change in polymer oxidation state might also have taken place. [Copyright &y& Elsevier]

Abstract: Chemical anchoring of silica nanoparticles onto polyaniline (PANI) chains was conducted through electro-co-polymerization of aniline and N-substituted aniline grafted on surfaces of silica nanoparticles. The grafting of N-substituted aniline on surfaces of silica nanoparticles were realized through hydrolysis of triethoxysilylmethyl N-substituted aniline (ND42) and the following condensation reaction with silanol groups on surfaces of SiO2. Organic–inorganic interactions between PANI and SiO2 involved in electro-co-polymerization process pushed the polymer chains apart and so facilitated the 1D growth of the polymer. Hence, the obtained hybrid film PANI/ND42–SiO2 displayed nano-fibrous morphologies (ca. 50nm in diameter). Consequently, PANI/ND42–SiO2 exhibited an average specific capacitance of 380Fg−1, ca. 40% higher than that of PANI/SiO2 (276Fg−1). The hybrid film also showed improved cyclic stability. [Copyright &y& Elsevier]

Abstract: Hybrid films of polyaniline (PANI) and manganese oxide (MnO x ) were obtained through potentiodynamic deposition from solutions of aniline and MnSO4 at pH 5.6. The hybrid films demonstrated characteristic redox behaviors of PANI in acidic aqueous solution. Characterization of the hybrid films by XRD indicated the amorphous nature of MnO x in the films in which manganese existed in oxidation states of +2, +3 and +4, based on XPS measurement. Hybrid film of PANI and MnO x , PM120 obtained from the solution of 0.1M aniline and 120mM Mn2+ displayed a well opened nanofibrous structure which showed an 44% increase in specific capacitance from that of PANI (408Fg−1) to 588Fg−1, measured at 1.0mAcm−2 in 1M NaNO3 (pH 1). The hybrid film kept more than 90% of its capacitance after 1000 charging-discharging cycles, with a coulombic efficiency of 98%. The specific capacitance of a symmetric capacitor using PM120 as the electrodes is 112Fg−1. [Copyright &y& Elsevier]

Abstract: Electrocodepositions were conducted in solutions of aniline and MnSO4 through potential cycling to afford hybrid films of polyaniline (PANI) and manganese dioxide (PANI/MnO2). The films obtained displayed characteristic redox peaks of PANI on cyclic voltammograms in acidic aqueous solution. While in 1.0M NaNO3 at pH 1, the films showed pseudocapacitive behaviors from 0 to 0.65V vs. SCE. MnO2 was detected through XRD and XPS measurements on the films. The codeposition of PANI with MnO2 had dramatic effects on morphologies of the obtained hybrid films that displayed fibrous morphologies instead of granular one of PANI. Hybrid film PM50 obtained in the presence of 50mM Mn2+ displayed a specific capacitance of 532Fg−1 at 2.4mAcm−2 discharging current, 26% higher than that of similarly prepared PANI. It showed a coulombic efficiency (η) of 97.5% over 1200 cycles with 76% specific capacitance maintained. [Copyright &y& Elsevier]

Abstract: Composite films of tungsten oxide (WO3) and polyaniline (PANI) have been electrodeposited by cyclic voltammetry in a mixed solution of aniline and precursor of tungsten oxide. Surface morphology and chemical composition of WO3/PANI composite are characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The influence of H2O2 on the electrodeposition of WO3/PANI composite film is also investigated. Cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS) results show that WO3/PANI composite film exhibit good pseudocapacitive performance over a wide potential range of −0.5 to 0.7V vs. SCE with the specific capacitance of 168Fg−1 at current density of 1.28mAcm−2 and energy density of 33.6Whkg−1, which is 91% higher than that of similarly prepared PANI (17.6Whkg−1). An asymmetric model capacitor using WO3/PANI as negative and PANI as positive electrodes over voltage range of 1.2V displays a specific capacitance of 48.6Fg−1 and energy density of 9.72Whkg−1 at the power density of 53Wkg−1, which is two times higher than that of a symmetric capacitor modeled by using two PANI films as both positive and negative electrodes. [Copyright &y& Elsevier]

Abstract: Electrodeposition of polyaniline (PAni) was performed across a broad pH range from pH 0.0 to 14.0. PAni films were found to grow from strong acidic environments at much faster rate and appeared to adopt different growth patterns from those grown from higher pH media, thus producing PAni films with very different morphologies ranging from nanofibres to microsized tubules to flakes like structures. The various morphologies of the PAni films were results of homogeneous and heterogeneous nucleation during electrochemical polymerization. These phenomena occurred under specific conditions which could be induced by varying the pH of the reaction media. Characteristic IR absorptions of the films deposited from increasing pH environment indicated little differences in chemical structure of the polymers except for the film grown from pH 14.0. Cyclic voltammetry data also indicated different electron transfer efficiency as a result of different morphology adopted. All except for PAni films obtained from pH 2.0 to 4.0 gave high specific capacitance at around 450Fg−1 in 0.5M H2SO4 and in 1.0M NaNO3 (pH 1.0) solution using 1.0mAcm−2 charging and discharging current density. [Copyright &y& Elsevier]

Direct electrochemical growth of polyaniline nanowire arrays (PANI NWAs) on surfaces of graphene sheets in partially exfoliated graphite foil (Ex-GF) was achieved through electropolymerization of aniline to fabricate hierarchical nanostructured pseudocapacitive electrodes. The PANI NWAs were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Due to the combined merits of PANI NWA and graphene sheets, the hierarchical nanostructured electrodes demonstrated high pseudocapacitive performances. More importantly, fast capacitance fading of pseudocapacitive materials upon mass loading increase can be suppressed by the novel structure, making it a good candidate for supercapacitor electrode with high areal capacitance. The PANI NWA with a high mass loading of 5.89 mg cm −2 showed an exceptionally high areal capacitance of 3.57 F cm −2 and a quite high specific capacitance 607 F g −1 . 72.4% of the capacitance can be retained when the discharge current increase 10 times, demonstrating its high rate capability. [ABSTRACT FROM AUTHOR]

Abstract: Carbon cloth was functionalized through cyclic voltammetric scans in 2M H2SO4 to afford functionalized carbon cloth (FC). The FC was characterized by Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). Self-doped polyaniline (SPAN) was deposited on FC through electro-co-polymerization of aniline and metanilic acid to get SPAN/FC which showed a specific capacitance of 408Fg−1 in 0.5M Na2SO4, based on a constant charge–discharge experiment at a current density of 1Ag−1. A symmetric model capacitor, SPAN/FC-SPAN/FC was assembled by using SPAN/FC as both of the electrodes and 0.5M Na2SO4 as the electrolyte. The charge storage property and charge–discharge cycling stability of SPAN/FC-SPAN/FC were investigated by galvanostatic experiment. [Copyright &y& Elsevier]

Abstract: Composites of polyaniline (PANI) and a unique ordered mesoporous carbon MPC which possesses small pores inside the carbon walls have been prepared. The monomer (aniline) of PANI is firstly soaked in the small pores inside the carbon walls and then confined in the primary mesochannels as well with increasing the concentration of aniline in the soaking solution. After the following in situ polymerization, composites of PANI and MPC with bicontinuous interpenetrating framework are formed. The composites show significant redox activities at potentials negative to 0V vs. Hg/HgO in a strong alkaline solution, which is unusual for PANI and PANI based composites as PANI usually loses its electrochemical activity at pH>4. The specific capacitance of the composites is as high as 400Fg−1 at a high current density of 1Ag−1 in the potential range of −0.7 to 0V, which is twice higher than that of the host MPC. The capacitance only decreases about 9% when the discharge current density increases from 1 to 20Ag−1, indicative of excellent rate capability. Therefore, the composites are very promising for the application as electrode materials in supercapacitors, especially as materials for negative electrode in hybrid supercapacitors. [ABSTRACT FROM AUTHOR]

Abstract: We report the synthesis and pseudocapacitive studies of a composite film (PANI-ND-MnO2) of polyaniline (PANI) and manganese oxide (MnO2) nanoparticles. To enhance the interaction of MnO2 and PANI, the surfaces of MnO2 nanoparticles were modified by a silane coupling reagent, triethoxysilylmethyl N-substituted aniline (ND42). The composite film was obtained via controlled electro-co-polymerization of aniline and N-substituted aniline grafted on surfaces of MnO2 nanoparticles (ND-MnO2) on a carbon cloth in a electrolyte of 0.5M H2SO4 and 0.6M (NaPO3)6. In comparison to similarly prepared PANI film, the incorporation of MnO2 nanoparticles substantially increases the effective surface area of the film by reducing the size of rod-like PANI aggregates and avoiding the entanglement of these PANI nanorods. Significantly, we observed significant enhancement of specific capacitance in PANI-ND-MnO2 film compared to PANI–MnO2 film prepared in a similar condition, indicating that the presence of the coupling reagent can improve the electrochemical performance of PANI composite film. A symmetric model capacitor has been fabricated by using two PANI-ND-MnO2 nanocomposite films as electrodes. The PANI-ND-MnO2 capacitor showed an average specific capacitance of ∼80Fg−1 and a stable coulombic efficiency of ∼98% over 1000 cycles. The results demonstrated that PANI-ND-MnO2 nanocomposites are promising materials for supercapacitor electrode and the importance of designing and manipulating the interaction between PANI and MnO2 for fundamentally improving capacitive properties. [Copyright &y& Elsevier]

Abstract: Composite material PANI/KIT-6, with polyaniline (PANI) chains encapsulated in the 3-D interconnected pore channels of mesoporous silica, KIT-6, has been synthesized via a gas-phase method. The composite formation and the presence of PANI inside the pore channels of KIT-6 were evidenced by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), small-angle X-ray scatter (SAXS), transmission electron microscopy (TEM), and N2 adsorption–desorption isotherms. The PANI/KIT-6 composite showed good electrical conductivity (2.4×10−3 S/cm) due to the formation of 3-D networks of PANI inside the 3-D interconnected channels of KIT-6. The resistance of PANI/KIT-6 composite at different relative humidities (RH) was investigated. An essentially linear relationship between the relative resistance of the composite and the relative humidity of the environment was found from 11.3% to 97.3% RH. [Copyright &y& Elsevier]