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: Composite film of polyaniline (PANI) and tungsten oxide (WO3) was electrodeposited by cyclic voltammetric technique from a solution of aniline and tungstic acid. The obtained WO3/PANI film displayed a significant enhancement of electrocatalytic activity for iodate reduction and a better stability than that of pure WO3 and PANI films. Result of amperometric experiment revealed a good linear relationship with concentration of IO3 − from 20 to 500μM, with a high sensitivity of 0.54μA/μM and a detection limit of 2.7μM for the determination of iodate. This composite film was also successfully applied in determination of iodate in commercial table salt. [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]

Polyaniline-tungsten oxide composite films (PANI-WO x ) were prepared through concurrent electropolymerization of aniline and electrochemical deposition of tungsten oxide on partial exfoliated graphite (Ex-GF) for pseudocapacitive materials. The influence of aniline to WO x precursor ratio on pseudocapacitive properties of the afforded PANI-WO x /Ex-GF composite was investigated. PW-2:1/Ex-GF made from the solution containing aniline and WO x precursor in 2:1 ratio displayed a high specific capacitance (408 F g −1 /408 mF cm −2 at 1 A g −1 /1 mA cm −2 ) in a wide charge storage potential window of −0.6–0.7 V vs. SCE, leading to a high energy density of 95.8 Wh kg −1 at 650 W kg −1 . Due to the synergistic effect between WO x and PANI, the composite showed much improved cyclic stability (91.6% capacitance retention after 5000 galvanostatic charge–discharge cycles) compared to similarly prepared PANI/Ex-GF (69.1% capacitance after 5000 charge–discharge cycles). The assembled symmetric model supercapacitor, by using PW-2:1/Ex-GF as both of the electrodes, also displayed good stability and high energy density, demonstrating that the PANI-WO x composite is promising electrode material for high-performance supercapacitor. [ABSTRACT FROM AUTHOR]

[Display omitted] • A zinc-iodine battery with high coulombic efficiency and stability is proposed. • The polyiodide is confined at cathode by doping on polyaniline chains. • The complex in electrolyte is regulated to eliminate free iodide anions. • It delivers 99.2% coulombic efficiency with 2 mAh cm−2 capacity at 6 mA cm−2. • A stable capacity retention of 99.9% is achieved after 1000 cycles. Aqueous zinc-iodine batteries are promising electrochemical energy storage systems due to the high safety and low cost. The application of zinc halide solution as the electrolyte allows the dual-plating mechanism on both electrodes, i.e. the redox reactions of Zn2+/Zn and I 2 /I- at the anode and cathode, respectively. These solid–liquid conversion processes guarantee excellent reaction kinetics. However, soluble polyiodide (I 3 -, I 5 -, etc.) are formed at the cathode either during the oxidation of I- or from the reaction between I- and I 2. The dissolution of polyiodide in electrolytes causes rapid loss of charged products, leading to poor coulombic efficiency and fast self-discharge. Herein, we apply the synergistic regulation of electrode and electrolyte to confine the charged products. The conducting polymer polyaniline (PANI) is used as the polyiodide binder. It contains positively charged nitrogen sites, allowing the doping and effective binding of polyiodide anions through electrostatic attraction. At the same time, the complex in zinc halide electrolytes is regulated to eliminate free iodide anions and prevent the reaction with I 2 to form more polyiodide. The optimized zinc-iodine aqueous battery delivers excellent rate capability thanks to the facile solid–liquid reactions as well as the high electrical conductivity of PANI. More importantly, it achieves a high coulombic efficiency of 99.2% with the capacity of 2 mAh cm−2 at 6 mA cm−2, and an excellent capacity retention of 99.9% after 1000 cycles is realized upon long-term cycling. The work proposes a potential pathway to realize stable energy storage in aqueous zinc-halogen batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • The leucoemeraldine-emeraldine-pernigraniline reactions of PANI are realized by Nernst shift. • The pernigraniline hydrolysis is inhibited with low water activity in electrolyte. • The PANI cathode delivers 221 mAh g−1 capacity at 0.2 A g−1 in aqueous Zn batteries. • A stable capacity retention of 96.6% is achieved after 1000 cycles at 3 A g−1. Polyaniline (PANI) is a promising cathode material for aqueous zinc batteries. However, only half available capacity based on the leucoemeraldine-emeraldine redox reaction can be used. Further oxidation to pernigraniline requires potential exceeding the top voltage limit of aqueous solutions, and the hydrolysis of pernigraniline leads to PANI degradation. Herein, we show that the redox potential of emeraldine-pernigraniline reaction is effectively shifted within electrolyte voltage window by tuning ion activities in electrolyte based on Nernst shift, so that both redox processes of PANI are realized for energy storage in aqueous zinc cells. Meanwhile, the pernigraniline hydrolysis is inhibited with limited water activity in the concentrated electrolyte, and the long-term stability in ensured. The PANI electrode delivers a high capacity of 221 mAh g−1 at 0.2 A g−1 and maintains 118 mAh g−1 at 5 A g−1 in aqueous zinc batteries. An excellent capacity retention of 96.6% is achieved after 1000 cycles with 99.7% coulombic efficiency. The energy storage processes as well as the active dopants on PANI are identified by a series of characterizations. The work demonstrates an effective strategy to realize energy storage with redox couples outside the voltage window of conventional electrolytes. [ABSTRACT FROM AUTHOR]

Abstract: Geometry optimization was conducted on a series of emeraldine salt (ES) oligoanilines (2x +2)-ES+ (x =0, 1, 2, 3), alcohols and complexes composed of oligoanilines and alcohols by density functional theory (DFT) method at UB3LYP/6-31g (d) level. Electronic properties of complexes composed by (2x +2)-ES+ oligoanilines with methanol, ethanol, propanol and isopropanol were investigated at higher level UB3LYP/6-311++g (d, p) to model the response of polyaniline (PANI) to alcohols. Influences of oligoaniline chain length and alcohols on the binding properties of the complexes were discussed based on the calculated results. [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: Polyaniline and molybdenum oxide composite modified electrode (PANI–MoO3) was prepared through immobilization of the oxide in the polymer matrix. The obtained composite was characterized by XPS and FTIR. Stability and electrocatalytic properties of the composite for the reduction of chlorate were investigated by using cyclic voltammetry and chronoamerometry. It was found that the electrocatalytic activity of MoO3 towards the reduction of chlorate is improved by immobilization in PANI. The composite modified electrode showed a quick response time of 10s to chlorate. Results of amperometric measurements at a working potential of 0.0V vs. SCE showed that the composite modified electrode displayed linear amperometric responds to chlorate in a concentration range of 5μM–10.0mM with a lower detection limit (LOD) of 1.3μM. The stability of MoO3 was also improved through immobilization in PANI. [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]

[Display omitted] • Quinone sites are introduced to PANI by a facile electrochemical method. • Polymer chains transform into expanded coil conformation at the same time. • Quinone provides extra redox sites, and expanded polymer enhances conductivity. • The electrode delivers 186 mAh g−1 capacity with quinone at 1.4 V and PANI at 1.1 V. • A stable capacity retention of 88.0% is achieved after 1500 cycles. Rechargeable aqueous batteries with zinc metal anodes are promising energy storage systems owing to their high safety and low lost. A suitable cathode material is in urgent demand. Organic materials offer adjustable electrochemical activity, and conducting polymers provide good electrical conductivity. Herein, we combine those advantages in one cathode material by the controlled introduction of quinone-type active sites onto polyaniline (PANI) nanorod-arrays through a facile electrochemical treatment. The process simultaneously transforms the polymer with a compact coil conformation into an expanded coil structure, resulting in facilitated electron transportations and charge transfer processes. In comparison to the original PANI, the electrochemically treated Q-PANI electrode exhibits extra electrochemical activity from quinone sites as well as enhanced capacity from PANI itself. Q-PANI delivers a high capacity of 186 mAh g−1 at 0.2 A g−1. Upon long-term cycling, 88.0% capacity retention is achieved after 1500 cycles at 2 A g−1. Detailed mechanism studies demonstrate the redox reaction on quinone sites at 1.4 V and nitrogen centers in PANI at 1.1 V. The work proposes a potential pathway towards high performance electrode materials for zinc batteries. [ABSTRACT FROM AUTHOR]