Porous Polyaniline Research Articles

Anti-scaling properties of a SLIPS material prepared by silicon oil infusion in porous polyaniline obtained by electropolymerization

Surfaces termed SLIPS (Slippery Liquid-Infused Porous Surface) present quite singular properties, for instance, self-healing and self-cleaning, which make them very promising for a broad range of applications in so diverse fields such as medical, avionic, oil and gas industries, among others. Considering that scaling is a crucial problem in many industrial facilities in this work the anti-scaling ability of one SLIPS was evaluated. This SLIPS was prepared by infusion of silicon oil into porous electropolymerized and silanized polyaniline. Aniline electropolymerization produced a coating with a textured morphology that was then modified by silanization to allow a complete wetting by the silicon oil used to impregnate the textured surface and avoid its leakage during the scaling and cleaning stages. This material, termed E-PANI3-S, was submitted to scaling test by immersion into a brine with a composition similar to the formation water found in some oil wells and was assessed by scanning electronic microscopy (SEM), showing clear anti-scaling properties.

Sn-Cu nanotubes enveloped in three-dimensional interconnected polyaniline hydrogel framework as binder-free anode for lithium-ion battery

The novel Sn-Cu nanotubes enveloped in three-dimensional (3D) hierarchical polyaniline (PANI) hydrogel (Sn-Cu/PANI) were successfully prepared as a high performance anode for lithium-ion battery. The binder-free electrode exhibits reversible capacity of 548mA h g−1 after 500 cycles and admirable rate capacity even up to 5000mAg−1. The exceptional electrochemical performance of Sn-Cu/PANI hydrogel could be attributed to the unique structure: (1) The inactive Cu matrix in binary Sn-Cu compounds and the tubular construction conduce to relieve the volume swing; The high porosity originated from galvanic replacement reaction accelerates ions transmission, which contributes to rapid charging and discharging. (2) The 3D porous PANI framework offers a continuous electron and lithium ions transport network among the whole electrode; the hierarchical PANI serves as mechanical support to accommodate the stress related to the large volume change of Sn-Cu nanotubes, thus reducing the risk of electrode pulverization.

Influence of oCVD Polyaniline Film Chemistry in Carbon-Based Supercapacitors

Polyaniline (PANI) is integrated into Mo2C carbide-derived-carbon (CDC) electrodes using the single-step, solvent-free process of oxidative chemical vapor deposition (oCVD). By optimizing the oCVD processing conditions, CDC electrodes integrated with oCVD PANI exhibit more than double the gravimetric capacitance (115 F/g) vs bare CDC electrodes (52 F/g) and a 79% capacity retention after over 10 000 cycles. The oxidant flow rate, substrate temperature, and reactor pressure were varied, and their influence on film chemistry and supercapacitor performance was explored electrochemically and with FTIR and XPS. The study reveals that a higher substrate temperature, pressure, and oxidant flow rate are critical for depositing emeraldine PANI for optimal electrochemical performance. Interestingly, the optimally performing PANI-CDC devices have a porous PANI morphology as determined by SEM, which may facilitate ion transport, improve scan rate performance, and impart electric double layer capacitance in addition t...

Fabrication of porous polyaniline modified MWNTs core-shell structure for high performance supercapacitors with high rate capability

Novel porous polyaniline (PANI) modified MWNTs core-shell structure materials (porous CNTs-PANI) were fabricated by in situ polymerization using the “worm-like” MnO2 modified MWNTs (CNTs-MnO2) as the reactive template. The MnO2 layer on surface of MWNTs can act as the reactive template in the polymerization process. Meanwhile, the reactive etching of the MnO2 can form porous structure of PANI for fabrication of porous CNTs-PANI core-shell structure, which exhibits outstanding electrochemical performance among the CNTs-PANI and pure PANI materials. The porous CNTs-PANI materials possess an excellent specific capacitance of 406.5F/g at 0.5A/g, exhibit good rate capability of 84.7% even up to 50A/g, and keep 72% of its original value up to 1000 charge-discharge cycles at the current density of 10A/g, also maintain 55% capacitance retention at 2200 charge-discharge cycles. Furthermore, the porous CNTs-PANI materials exhibit an extremely high energy density of 55.6Wh/kg at the power density of 0.25kW/kg. The novel porous CNTs-PANI core-shell structure materials reveal promising applications in high performance supercapacitors.

Fabrications of Polyaniline Films by Pulse Electrodeposition in Acidic Solutions with Different Anions and Their Thermoelectric Performances

Polymerization of aniline was prepared by the pulse potentiostatic method in H3PO4, HClO4 and H2SO4 acidic solutions. The morphologies and thermoelectric performances were analyzed by scanning electron microscopy, Seebeck coefficient (S) and resistivity (R) measurements. The results show that flake polyaniline (PANI) films can be obtained in H3PO4 and HClO4 acidic solutions, and porous PANI films with nanofiber-overlapped structures can be prepared in H2SO4 solution under the same pulse parameters. PANI films prepared in the three solutions are all p-type thermoelectric materials. PANI films polymerized in H2SO4 solution possess the highest S (30.2 μV K−1) and lowest R (1.6 × 10−3 Ω m) compared with those prepared in H3PO4 and HClO4 solutions, indicating that nanofiber-overlapped structures formed in H2SO4 solution contribute better thermoelectric performance. In addition, the effects of pulse parameters (anodic potential φa, anodic pulse duration ta and cathodic pulse duration tc) on the surface morphologies and thermoelectric performances of PANI films were systematically investigated.

Synthesis and enhanced electrochemical performance of Pt-Ag/porous polyaniline composites for glycerol oxidation

Porous polyaniline (PANI) with enhanced surface area was obtained using attapulgite (ATP) as a template and then etched with HF acid. Pt-Ag/porous PANI nanocomposites were fabricated successfully via step-by-step electrodeposition method, and then characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR), and UV-visible spectrophotometer (UV-visible). The influence of deposition order and deposition laps of Pt, Ag towards glycerol oxidation was also studied. The results showed that when Pt was deposited first then Ag, and the deposition laps of both Pt and Ag were 300 laps, Pt-Ag/porous PANI (300/300) exhibited the best effect. The catalytic activity of Pt-Ag/porous PANI (300/300) was 3.14 times higher than that of the commercial 20wt.% Pt/C. In addition, the Electrochemical Impedance Spectroscopy (EIS), chronoamperometry and stability testing proved that the Pt-Ag/porous PANI (300/300) modified electrode showed not only excellent electrocatalytic activity but also better poison resistance and good stability towards glycerol oxidation in contrast to other as-prepared composites as well as commercial 20wt.% Pt/C catalysts, which may be ascribed to high utilization of Pt resulted from porous structure of support and the synergic effect between Pt and Ag.

Effect of charge carrier transport on sulfur dioxide monitoring performance of highly porous polyaniline nanofibres

Polyaniline nanofibres (NFs) with controlled diameters were synthesized using a template-free method, with ammonium peroxidisulfate (APS) or ferric chloride (FeCl3) as oxidants. Porosity studies reveal that NFs prepared with FeCl3 possess higher effective surface area and larger pore volume compared to NFs prepared with APS. The FeCl3-assisted NFs show around twofold enhanced sensing response (ca 4.5%) towards 5 ppm of SO2 at room temperature compared to APS-assisted NFs (ca 2%). The enhancement can be attributed to the lower diameter, higher effective surface area and larger porosity of FeCl3-assisted NFs. To further explain this enhanced sensing response, the conduction mechanism was studied. NFs possessing a smaller diameter (ca 10 nm) are found to follow the one-dimensional variable range hopping (VRH) model, whereas NFs with larger diameter (ca 100 nm) follow the conventional three-dimensional VRH model. This can be due to the restriction of charge carrier transport into only one direction due to quantum size effects. Furthermore, the calculated Mott parameters suggest that the NFs prepared using FeCl3 provide a better pathway for charge transport of charge carriers as compared to NFs prepared using APS in terms of shorter hopping distance, lower activation energy and lower hopping energy, and weaker localization of charge carriers.

Polymer Encapsulated Sulfur Nano-Composite for Long Cycle-Life Lithium Sulfur Battery

The lithium-sulfur (LiS) battery is of great interest owing to its remarkable theoretical capacity of 1672 mAh g-1 and specific energy of 2600 Wh kg-1. The low operating voltage of the LiS battery (~2.0 V) provides safety advantages over high-voltage cathode materials, and elemental sulfur is environmentally friendly and inexpensive. However, well-known issues in Li-S batteries include the loss of electrical contact, low electronic conductivity of sulfur, and shuttling of polysulfides during cycling. The shuttle effect is known to cause the low utilization of the sulfur, degradation of cycle-life and, low Coulombic efficiency in LiS batteries. Using conductive materials to encapsulate sulfur nano-particles to improve the electronic conductivity of sulfur and limit the polysulfide dissolution is one of the striking strategies for the development of LiS batteries of long cycle-life and high Coulombic efficiency (above 95%). Most polymer-encapsulated nanocomposites reported thus far require low-temperature treatment as well as long synthesis time, and have short cycle life barely exceeding 100 charge/discharge cycles. Here, we demonstrate that by controlling the pore size of the encapsulating polymer membrane, we can achieve significant improvement in the cyclability and Coulombic efficiency of an Li-S battery. Polyaniline is used as the encapsulating polymer membrane since it reacts with sulfur at high temperature to form a cross-linked structure, which is known to significantly improve the cycling performance. Morphology of the polymer may be controlled by intercalation of metal oxide nano-particles (e.g., MnO2, ZrO2, TiO2) into the pores of the porous polyaniline (PAN) as the encapsulating polymer. To accommodate the large volumetric expansion of sulfur during lithiation, sufficient empty space can be provided by heat treatment of the sulfur/PAN nano-composite. Up until now, the sulfur/PAN nano-composites production has required low- temperature treatment of reactants for 24-48 hours under nitrogen or argon atmosphere. As a unique advantage, we provide a simplified short-time (3 hours) synthesis method at room temperature under air atmosphere. Acknowledgment: This work is supported as part of the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences.

Brine solution-driven synthesis of porous polyaniline for supercapacitor electrode application

Increasing environmental and economic impacts has driven the need for development of inexpensive methodology for polymer nanostructure synthesis using non-toxic reagents. Herein, we report synthesis of porous polyaniline (PANI) by polymerization of aniline in brine (saturated sodium chloride) solution. The resulting polyaniline is highly porous, thus providing large surface area, which is a vital parameter for the significant improvement of supercapacitor performance. Brine solution acted as a pseudo-template for the formation of porous PANI, eliminating the need of organic solvents/acids and hard/soft templates. The porous PANI electrodes showed a high specific capacitance of 662 F/g, which is 2.5 times greater than that of conventional PANI. X-ray diffraction studies revealed an ordered nature of porous PANI chains as compared to conventional one, whereas their chemical nature is similar as confirmed by FTIR, and UV–visible spectroscopy. Polymerization reaction carried out at various concentration of NaCl solution helped to understand the evolution of porous morphology, based on which a plausible mechanism is proposed for formation of the porous polymer. Polymerization was also carried out in brine in the presence of other commercial acids like sulphuric and nitric acids, to demonstrate the versatility of using brine in polymerization. Effect of other saturated ionic medium such as KCl, Na2SO4 and non-ionic medium like glucose, on the polymerization reaction was also studied.

Polyaniline-Supported Bacterial Biofilms as Active Matrices for Platinum Nanoparticles: Enhancement of Electroreduction of Carbon Dioxide

A hybrid matrix composed of a porous polyaniline underlayer, a robust bacterial biofilm and a multiwalled carbon nanotube overlayer has been demonstrated to function as highly active support for dispersed Pt catalytic nanoparticles during the electroreduction of carbon dioxide in neutral medium (phosphate buffer at pH 6.1). In contrast with bare Pt nanoparticles (deposited at a glassy carbon substrate), application of the hybrid system produces sizeable CO2-reduction currents in comparison to those originating from hydrogen evolution. The result is consistent with an enhancement in the reduction of carbon dioxide. However, the biofilm-based matrix tends to inhibit the catalytic properties of platinum towards proton discharge (competitive reaction) or even oxygen reduction. The hydrated structure permits easy unimpeded flow of aqueous electrolyte at the electrocatalytic interface. Although application of the polyaniline underlayer can be interpreted in terms of stabilization and improvement of the biofilm adherence, the use of carbon nanotubes facilitates electron transfer to Pt catalytic sites. It is apparent from the voltammetric stripping-type analytical experiments that, although formation of some methanol and methanoic acid cannot be excluded, carbon monoxide seems to be the main CO2-reduction product.

Durable porous polyaniline supported ionic liquid coating for the highly effective solid phase microextraction of trace fatty alcohols in drinks

A polyaniline (PANI)-ionic liquid (IL) based solid phase microextraction (SPME) coating is presented.

Inkjet-printed porous polyaniline gel as an efficient anode for microbial fuel cells

An inkjet-printed polyaniline gel on carbon substrate was employed as an efficient anode to remarkably improve the performance of microbial fuel cells.

3D polyaniline porous layer anchored pillared graphene sheets: enhanced interface joined with high conductivity for better charge storage applications.

Here, we report synthesis of a 3-dimensional (3D) porous polyaniline (PANI) anchored on pillared graphene (G-PANI-PA) as an efficient charge storage material for supercapacitor applications. Benzoic acid (BA) anchored graphene, having spatially separated graphene layers (G-Bz-COOH), was used as a structure controlling support whereas 3D PANI growth has been achieved by a simple chemical oxidation of aniline in the presence of phytic acid (PA). The BA groups on G-Bz-COOH play a critical role in preventing the restacking of graphene to achieve a high surface area of 472 m(2)/g compared to reduced graphene oxide (RGO, 290 m(2)/g). The carboxylic acid (-COOH) group controls the rate of polymerization to achieve a compact polymer structure with micropores whereas the chelating nature of PA plays a crucial role to achieve the 3D growth pattern of PANI. This type of controlled interplay helps G-PANI-PA to achieve a high conductivity of 3.74 S/cm all the while maintaining a high surface area of 330 m(2)/g compared to PANI-PA (0.4 S/cm and 60 m(2)/g). G-PANI-PA thus conceives the characteristics required for facile charge mobility during fast charge-discharge cycles, which results in a high specific capacitance of 652 F/g for the composite. Owing to the high surface area along with high conductivity, G-PANI-PA displays a stable specific capacitance of 547 F/g even with a high mass loading of 3 mg/cm(2), an enhanced areal capacitance of 1.52 F/cm(2), and a volumetric capacitance of 122 F/cm(3). The reduced charge-transfer resistance (RCT) of 0.67 Ω displayed by G-PANI-PA compared to pure PANI (0.79 Ω) stands out as valid evidence of the improved charge mobility achieved by the system by growing the 3D PANI layer along the spatially separated layers of the graphene sheets. The low RCT helps the system to display capacitance retention as high as 65% even under a high current dragging condition of 10 A/g. High charge/discharge rates and good cycling stability are the other highlights of the supercapacitor system derived from this composite material.

Scalable synthesis of freestanding sandwich-structured graphene/polyaniline/graphene nanocomposite paper for flexible all-solid-state supercapacitor.

We reported a scalable and modular method to prepare a new type of sandwich-structured graphene-based nanohybrid paper and explore its practical application as high-performance electrode in flexible supercapacitor. The freestanding and flexible graphene paper was firstly fabricated by highly reproducible printing technique and bubbling delamination method, by which the area and thickness of the graphene paper can be freely adjusted in a wide range. The as-prepared graphene paper possesses a collection of unique properties of highly electrical conductivity (340 S cm−1), light weight (1 mg cm−2) and excellent mechanical properties. In order to improve its supercapacitive properties, we have prepared a unique sandwich-structured graphene/polyaniline/graphene paper by in situ electropolymerization of porous polyaniline nanomaterials on graphene paper, followed by wrapping an ultrathin graphene layer on its surface. This unique design strategy not only circumvents the low energy storage capacity resulting from the double-layer capacitor of graphene paper, but also enhances the rate performance and cycling stability of porous polyaniline. The as-obtained all-solid-state symmetric supercapacitor exhibits high energy density, high power density, excellent cycling stability and exceptional mechanical flexibility, demonstrative of its extensive potential applications for flexible energy-related devices and wearable electronics.

Highly porous nanostructured polyaniline/carbon nanodots as efficient counter electrodes for Pt-free dye-sensitized solar cells

A novel method to synthesize highly porous polyaniline (PANI) using carbon nanodots (CNDs) is reported. PANI-CND nanocomposite films exhibited high electrical conductivity (774 S cm−1) and excellent performance as counter electrodes in dye-sensitized solar cells (η = 7.45%).

Electrodeposition of Porous Polyaniline Coating on an Etching Stainless Steel Wire as a Fiber for Solid-Phase Microextraction of Triclosan and Chlorophenols in Water Samples

A novel polyaniline (PANI) coating doped with perchlorate ions was prepared on a stainless steel (SS) wire by a three-electrode system. Before electrodeposition, the SS wire was etched by hydrofluoric acid to enhance its surface roughness. The prepared PANI-coated fiber was used for solid-phase microextraction (SPME) of 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP) and triclosan (TCS) in water samples followed by high-performance chromatography with UV detection (HPLC-UV). The extraction procedure was optimized. The proposed SPME-HPLC-UV method provided a wide linear range. The limits of detection were 0.006 ng/mL for 2-CP, 0.005 ng/mL for 2,4-DCP and 0.04 ng/mL for TCS, respectively. It was successfully applied to the analysis of spiked surface water samples with the recoveries from 99.6% to 109%.

High performance dye-sensitized solar cell by using porous polyaniline nanotubes as counter electrode

High efficiency and low cost dye-sensitized solar cells (DSSCs) have attracted much attention very recently in the context of our need for an affordable renewable energy source. Inexpensive porous polyaniline nanotubes (PPNT-1) have been synthesized through a simple method via controlled polymerization of aniline with ammonium persulfate in the presence of concentrated orthophosphoric acid. PPNT-1 has been used as a substitute for platinum to construct the counter electrode (CE) in a DSSC, which showed lower charge transfer resistance and higher electrocatalytic activity for reduction of I3- into I− than that of Pt electrode. PPNT-1-10T CE achieved a high conversion efficiency of 5.57%, matching the performance of otherwise identical DSSCs with Pt CE (5.20%).

Polyaniline Hybrid with Inverse Opal Structure for Fabrication of Thermoelectric Materials

The colloidal crystal template or opal with a closed-packed face centered cubic (fcc) lattice was prepared from monodisperse polystyrene (PS) microspheres by gravity sedimentation, and it was used for the fabrication of polyaniline hybrid with inverse opal structure. The template provided void space for the infiltration of Bi2Te3 and monomer that was then in situ polymerized to polyaniline. The opal composite was then soaked in toluene for completely removing PS microspheres to form porous polyaniline hybrid with inverse opal structure. The PS microspheres were replaced by air microspheres, which interconnected each other through the windows on the polyaniline hybrid wall. Both the wall and the air void constitute continuous phases. The polyaniline hybrid with inverse opal structure was observed with scanning electronic microscopy.

Three-Dimensional Macroporous Graphene Foam Filled with Mesoporous Polyaniline Network for High Areal Capacitance

Bicontinuous macroporous graphene foam composed of few-layered graphene sheets provides a highly conductive platform on which to deposit mesoporous polyaniline via incorporation of electrodeposition and inkjet techniques. The experimental results exhibit that the coating polyaniline thin layer on the surface of three-dimensional graphene foam via electrodeposition is of importance for changing the hydrophobic surface to a hydrophilic one and for the subsequent filling of the mesoporous polyaniline network into the macroporous graphene foam. The porous polyaniline network with high pseudocapacitance is highly efficient for adjusting the pore structure and capacitive properties of graphene foam. When used as electrode materials for supercapacitors, the resulted graphene foam–polyaniline network with high porosity renders a large areal capacitance of over 1700 mF cm–2, which is over two times the enhancement in comparison with the pure graphene foam and polyaniline thin layer coated one. The ultrahigh areal capacitance benefits from the synergistic effect of the good conductive graphene backbone and high pseudocapacitive polyaniline.

Evaluation of the Counter Ions in Doped Porous Polyaniline Coatings on Stainless Steel Wires for Solid Phase Microextraction of Chlorophenolics in Water Combined with High-Performance Liquid Chromatography

Porous polyaniline coatings doped with different counter ions were electrodeposited on the surface of stainless steel wires using controlled potentiostatic coulometry. Prior to electropolymerization, the stainless steel wires were chemically etched to improve subsequent immobilization of the polyaniline coatings on the substrate and to increase the effective surface area. Porous polyaniline coatings doped with sulfate, nitrate, and perchlorate counter ions were employed for solid-phase microextraction (SPME) of 2-chlorophenol, 2,4-dichlorophenol, triclosan, and 2,4-dichlorophenoxyacetic acid coupled to high-performance liquid chromatography. The results demonstrated that the perchlorate doped polyaniline coating exhibited the highest extraction efficiency for 2-chlorophenol, 2,4-dichlorophenol, and triclosan at pH 5.0, indicating that the extraction capability was modified by introducing different counter ions into the coatings. As a result, the perchlorate doped polyaniline coated fiber was further used for the optimization of extraction condition s . The method provided linear dynamic ranges over 2 to 4 orders of magnitude. The limits of detection were 0.006 µg · L−1, 0.005 µg · L−1, and 0.040 µg · L−1 for 2-chlorophenol, 2,4-dichlorophenol, and triclosan, respectively. The precision expressed as the relative standard deviation ranged from 2.20% to 5.04% for spiked water at 10 µg · L −1 (n = 5) and the fiber to fiber reproducibility was between 3.27% and 5.91% (n = 5). The method was successfully applied to the determination of chlorophenolics in real water samples. The recoveries of chlorophenolics in spiked water at 5.0 µg · L−1 were between 99.60% and 108.7% with relative standard deviations between 3.24% and 5.47%.