Oxidative Polymerization Of Aniline Research Articles

Biocompatible PANI-Encapsulated Chemically Modified Nano-TiO2 Particles for Visible-Light Photocatalytic Applications.

Polyaniline (PANI) constitutes a very propitious conductive polymer utilized in several biomedical, as well as environmental applications, including tissue engineering, catalysis, and photocatalysis, due to its unique properties. In this study, nano-PANI/N-TiO2 and nano-PANI/Ag-TiO2 photocatalytic composites were fabricated via aniline's oxidative polymerization, while the Ag-and N-chemically modified TiO2 nanopowders were synthesized through the sol-gel approach. All produced materials were fully characterized. Through micro-Raman and FT-IR analysis, the co-existence of PANI and chemically modified TiO2 particles was confirmed, while via XRD analysis the composites' average crystallite size was determined as ≈20 nm. The semi-crystal structure of polyaniline exhibits higher photocatalytic efficiency compared to that of other less crystalline forms. The spherical-shaped developed materials are innovative, stable (zeta potential in the range from -26 to -37 mV), and cost-effective, characterized by enhanced photocatalytic efficiency under visible light (energy band gaps ≈ 2 eV), and synthesized with relatively simple methods, with the possibility of recycling and reusing them in potential future applications in industry, in wastewater treatment as well as in biomedicine. Thus, the PANI-encapsulated Ag and N chemically modified TiO2 nanocomposites exhibit high degradation efficiency towards Rhodamine B dye upon visible-light irradiation, presenting simultaneously high biocompatibility in different normal cell lines.

2‐Dimensional Magnesium Oxide/Polyaniline Nanocomposite Modified Glassy Carbon Electrode for Electrochemical Detection of Dopamine and 4‐Nitrophenol

AbstractIn this study, we have developed an electrochemical sensor based on a polyaniline (PANI) integrated magnesium oxide nanosheet (MgO‐NSs) modified glassy carbon electrode (GCE) for the rapid electrochemical detection of dopamine (DA) and 4‐nitrophenol (4‐NP). 2‐D MgO‐NSs were synthesized using a straightforward one‐step sugar‐blowing method, and PANI was synthesized by the oxidative polymerization of aniline. The nanocomposite (PANI‐MgO) was prepared by simple mechanical blending of MgO‐NSs with PANI. The as‐synthesized nanocomposites were characterized using several analytical techniques to determine their morphological and microstructural properties. The as‐synthesized PANI, MgO, and PANI‐MgO were further electrochemically characterized using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) techniques. The fabricated PANI‐MgO/GCE showed a considerable increase in the redox peak currents of DA and 4‐NP, suggesting that PANI‐MgO/GCE substantially enhances the electrocatalytic oxidation of DA and the reduction of 4‐NP. The analytical performance of PANI‐MgO/GCE for the detection of DA and 4‐NP was investigated using Differential Pulse Voltammetry (DPV). The developed sensor was successfully applied for the detection of DA and 4‐NP in real samples with good recovery results.

Epoxy coating reinforced with graphene-PANI nanocomposites for enhancement of corrosion-resistance performance of mild steel in saline water

Protective coatings enriched with different types of chemical additives, functional fillers, and nanostructured materials are gaining immense interest to minimize corrosion. The present work demonstrates the synthesis of chemically functionalized reduced graphene oxide (rmGO) and emeraldine salt form of polyaniline (PANI-ES)-based rmGO-PANI-ES nanocomposites as protective functional fillers for epoxy coating to inhibit mild steel corrosion. The oxidative polymerization of aniline into PANI-ES is initiated on nitrogen-rich active sites of rmGO, and it propagates along the basal plane of rmGO, eventually enwrapped the graphene sheets by interfacially grown PANI-ES. The synthesis of rmGO-PANI-ES nanocomposites and their chemical, morphological, crystalline, and structural characteristics are examined by the FTIR, 13C NMR, XPS, XRD, Raman, SEM, and HRTEM analyses. The multiple interactions between the highly polar nitrogen-rich rmGO-PANI-ES nanocomposites and the epoxy matrix strengthened the coating and increased the hardness and elastic modulus. The corrosion inhibition performance of epoxy coating enriched with the rmGO-PANI-ES nanocomposites is probed by electrochemical impedance spectroscopic (EIS) and salt spray tests using an accelerated corrosive environment (3.5 wt% NaCl). The rmGO-PANI-ES-15 nanocomposite having 0.15 wt% rGO in epoxy coating showed superior corrosion inhibition performance. The total electrochemical impedance of epoxy coating (8.7 ×103 Ω.cm2) increased to 4.7 ×1015 Ω.cm2 after incorporating 1 wt% rmGO-PANI-ES-15 nanocomposite. The enhancement of electrochemical impedance by ∼12 orders of magnitude demonstrates the effectiveness of the rmGO-PANI-ES nanocomposites for corrosion mitigation in a harsh corrosive environment. The high surface area and remarkable structural barrier of the 2D chemically functionalized graphene furnished excellent protective coverage. The PANI-ES of rmGO-PANI-ES nanocomposites formed a passive layer of fully reduced leucoemeraldine base of PANI (PANI-LEB) on the coating-mild steel interface by accepting the electrons, generated during the anodic oxidation of iron. These events collectively increase the impedance by multifolds and inhibit steel corrosion. The present findings revealed that graphene-enriched conductive polymeric nanocomposites-based coatings can be promising solution to mitigate corrosion of metal-based installations in a marine environment.

Fruit waste-derived cellulose-polyaniline composite for adsorption-coupled reduction of chromium oxyanions.

Hexavalent chromium oxyanions, known as potentially toxic micropollutants, exist in the effluents and discharges of metallurgical, electroplating, refractory, chemical, and tanning industries. The exposure of chromium-contaminated water causes severe health hazards. The present work outlines a facile approach to grow polyaniline (PANI) on fruit-waste-derived cellulose (CEL) via oxidative polymerization of aniline; followed by chemical processing with NH4OH to obtain CEL-PANI-EB composites for adsorptive separation-coupled reduction of highly toxic hexavalent chromium oxyanions. The spectroscopic analyses of the CEL-PANI-EB composite before and after adsorption of Cr(VI) oxyanions revealed hydrogen bonding, electrostatic, and complexation as major interactive pathways. The adsorbed hexavalent chromium oxyanions are reduced into Cr(III) species by oxidation of PANI-based benzenoid amine into quinoid imine in the CEL-PANI-EB composite. The adsorption of Cr(VI) oxyanions by the CEL-PANI-EB composite showed negligible effects of other anionic co-pollutants, like NO3- and SO42-. The CEL-PANI-EB composite adsorbed Cr(VI) oxyanions with a removal capacity of 469mgg-1, based on the Langmuir adsorption isothermmodel. The hydroxyl functionalities in cellulose and amine/imine functionalities in PANI facilitate the electrostatic attraction between the CEL-PANI-EB and Cr(VI) oxyanions in an acidic environment beside the hydrogen linkages. The adsorbed Cr(VI) oxyanions are reduced to Cr(III)-based species by the benzenoid amines of PANI, as revealed from the XPS analyses. The CEL-PANI-EB composite showed excellent recyclability and maintained 83.4% adsorption efficiency after seven runs of chromium adsorption-desorption. The current findings reveal the potential of CEL-PANI-EB composites for the adsorptive removal of Cr(VI) oxyanions and their conversion into a lesser toxic form, making them promising materials for wastewater treatment applications.

Investigation of ternary composites of polyaniline comprising benzalazine and nickel ions and its characterization

Recent research works are based on ternary polyaniline composite with nickel oxides, nickel ferrite, cobalt (II), copper (II) doped with graphene, manganese, PVA, carbon and more. Nickel itself being a magnetic material it is much suitable for super capacitive behaviour. Incorporating Nickel (II) chloride and Benzalazine in polyaniline composite will enhance its electromagnetic, electrochemical and mechanical properties. In the present work, ternary composites containing polyaniline, benzalazine and nickel (II) chloride were synthesized by the oxidative polymerization of aniline with different weight percentages of benzalazine and Nickel (II) chloride. Benzalazine gets physically adsorbed on the polymer chain and nickel ions get coordinated in the polymer chain. X-ray diffraction pattern was carried out to determine the crystalline nature of the synthesized samples. The synthesized polymer composites were subjected to the technique of Ultraviolet visible and Fourier transform infrared spectroscopic techniques to find out the optical properties. Surface morphology of the synthesized samples were analyzed using atomic force microscopy and Scanning electron microscopy. Redox behavior and capacitance studies were carried out by using cyclic voltammetry at different solution pH value and the synthesized composites at solution pH value pH 1.0 found to exhibit well defined capacitance behavior.

Bilayer Heterogeneous Cation Exchange Membrane with Polyaniline Modified Homogeneous Layer: Preparation and Electrotransport Properties.

A bilayer membrane based on a heterogenous cation exchange membrane with a homogeneous cation exchange layer and a polyaniline on its surface is prepared. The intercalation of polyaniline into the membrane with a homogeneous cation exchange layer is performed by oxidative polymerization of aniline. The influence of the homogeneous cation exchange layer and the polyaniline on the structure, conductivity, diffusion permeability, selectivity, and current-voltage curve of the heterogeneous cation exchange membrane is established. Membrane properties are studied in the HCl, NaCl, and CaCl2 solutions. The homogeneous cation exchange layer has a negligible effect on the transport properties of the initial heterogeneous membrane. The polyaniline synthesis leads to a decrease in the macropore volume in the membrane structure, conductivity, and diffusion permeability. The counterion transport number in the bilayer membrane is significantly reduced in a solution of calcium chloride and practically does not change in sodium chloride and hydrochloric acid. In addition, the asymmetry of the diffusion permeability and shape of current-voltage curve depending on the orientation of the membrane surface to the flux of electrolyte or counterion are found.

Revealing the causes of degradation of an asymmetric ionic liquid supercapacitor with a composite polyaniline/carbon electrode

The extended window of electrochemical stability of ionic liquids and the high specific capacitance values of activated carbon (AC)/conductive polymer (polyaniline, Pani) composite materials are promising approaches to improve the performance of supercapacitors (SC).In this work, we studied the stability of an asymmetric AC//Pani-C cell with 1 M solution of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) in acetonitrile as an electrolyte. Pani-C (56 wt% of Pani) composite was prepared by oxidative polymerization of aniline in the presence of high surface area AC (SBET = 2300 m2‧g−1). Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission and scanning electron microscopies data confirmed the formation of Pani-C composite. Combination of cyclic voltammetry, galvanostatic charge/discharge method, and electrochemical impedance spectroscopy in 2- and 3-electrode cell configurations gave information about anodic (1 V vs. Ti) and cathodic (−1.8 V vs. Ti) potential limits of electrochemical stability, and potential of zero charge of Pani-C and AC.From these data, optimal mass ratio of Pani-C and AC electrodes was obtained for asymmetric SC assembly. It was found that after 500 charge/discharge cycles, the capacitance of the asymmetric AC//Pani-C SC decreased by 15% from 46.8 to 39.9 F·g−1 as a result of Pani-C degradation. The specific capacitance of AC remained virtually unchanged (decreased from 144 to 141 F·g−1), while that of Pani-C decreased by 8.7% from 230 to 210 F·g−1. Electrochemical measurements showed that degradation is accompanied by an increase in the working potential window of Pani-C (from 0.85 V to 0.97 V) and a shift in Emin…Emax working potentials from 0.15 … 1 to 0.52 … 1.49 V vs. Ti in the beginning and in the end of stability test, respectively. The last region is related to the potential for non-conductive pernigraniline formation (1.3 V vs. Ti). It was shown that the main reason of AC//Pani-C SC capacitance decay is a gradual increase in the operating potential window with a constantly shifts towards anodic values of positive Pani-C electrode, which resulted in accumulation of nonconductive polymer form that does not participate in charge accumulation.

Pickering emulsions as an effective route for the preparation of bioactive composites: A study of nanocellulose/polyaniline particles with immunomodulatory effect

Several studies have reported on application of cellulose particles for stabilizing Pickering emulsions (PE). Here we employ an original approach that involves using these particles as a part of advanced composite colloids made of conducting polymer polyaniline (PANI) and cellulose nanocrystals (CNC) or nanofibrils (CNF). PANI/cellulose particles were prepared using oxidative polymerization of aniline in situ in the presence of CNC or CNF. The type and amount of celluloses (CNC vs CNF) and concentration of precursors (aniline monomer and oxidant) used in the reaction determined properties of the colloidal particles, such as size, morphology and content of PANI. The particles demonstrated intriguing biological characteristics, including no cytotoxicity, antibacterial activity against Staphylococcus aureus and Escherichia coli, antioxidant activity and related immunomodulatory activity. For the first time, such composites were used to successfully stabilize oil-in-water PE with undecane or capric/caprylic triglyceride oils. The properties of the emulsions were determined by the PANI/cellulose particles and oil used. The key finding of the study is the demonstrated ability of PANI/cellulose particles to stabilize PE, as well as the excellent antioxidant activity and ROS scavenging action originating from PANI presence, indicating potential of such systems for use in biomedicine, particularly for wound healing.

Optical, structural and conductivity properties of ferrous sulfate doped polyaniline

Conducting polyaniline -ferrous sulfate composite was prepared by the chemical oxidative polymerizing method by adding different weight % of finely powdered ferrous sulfate salt during polymerization of polyaniline. The oxidative polymerization of aniline is carried out by using ammonium persulfate as an oxidant. The synthesized PANI/FeSO4 composites were characterized with FTIR, XRD, SEM, DSC, UV–Vis., and discussed conducting properties. FTIR characterization is done in KBr medium, the results reveal the formation of polyaniline composite with ferrous sulfate. XRD characterization shows a decrease in the crystallinity of the PANI composite with an increase in dopant concentration and morphology also observed to change with dopant as revealed by the SEM images. Based on Differential Scanning Calorimetry (DSC) profiles one can see clear evidence for the insertion of the salt in the polymer matrix. The variation of band gaps with dopant concentration is studied using UV– Visible spectroscopy, which shows that both direct and indirect band gaps of the doped PANI decrease with increase in dopant concentration. The conductivity of PANI composite is found to increase with an increase in the concentration of the salt. These results show that doping with FeSO4 is a very effective technique for altering the electrical and optical properties of PANI.

Effect of a Zr-Based Metal–Organic Framework Structure on the Properties of Its Composite with Polyaniline

Composites of polyaniline (PANI) and Zr-based metal-organic frameworks (MOFs), UiO-66 and UiO-66-NH2, were synthesized by the oxidative polymerization of aniline in the presence of MOF templates with the MOF content in the resulting materials (78.2 and 86.7 wt %, respectively) close to the theoretical value (91.5 wt %). Scanning electron microscopy and transmission electron microscopy showed that the morphology of the composites was set by the morphology of the MOFs, whose structure was mostly preserved after the synthesis, based on the X-ray diffraction data. Vibrational and NMR spectroscopies pointed out that MOFs participate in the protonation of PANI and conducting polymer chains were grafted to amino groups of UiO-66-NH2. Unlike PANI-UiO-66, cyclic voltammograms of PANI-UiO-66-NH2 showed a well-resolved redox peak at around ≈0 V, pointing at the pseudocapacitive behavior. The gravimetric capacitance of PANI-UiO-66-NH2, normalized per mass of the active material, was also found to be higher compared to that of pristine PANI (79.8 and 50.5 F g-1, respectively, at 5 mV s-1). The introduction of MOFs into the composites with PANI significantly improved the cycling stability of the materials over 1000 cycles compared to the pristine conducting polymer, with the residual gravimetric capacitance being ≥100 and 77%, respectively. Thus, the electrochemical performance of the prepared PANI-MOF composites makes them attractive materials for application in energy storage.

Optimized formulation of polyaniline-pectin optical film sensor for pH measurement

Novel polyaniline-pectin (PAN-PEC) composite sensing films were prepared for optical pH measurement. Box–Behnken experiment design and the response surface method were used to optimize the PAN-PEC synthesis to produce films with a maximum color change response to pH change in the pH range of 2 to 12. The pH sensing PAN-PEC nanoparticles for incorporation in the sensing film were made by oxidative polymerization of aniline using ammonium persulfate as the oxidant and pectin as the stabilizer. The experimental factors were the quantity of aniline, the concentration of hydrochloric acid, and the mass of ammonium persulfate in the reaction mixture, for a fixed quantity of pectin. A relationship between spectrophotometric absorption at 420 nm and the pH was developed for estimating the pH of the samples.

Polyaniline/aramid composite for carbon dioxide capture

AbstractA novel composite based on conducting polymer, polyaniline/aramid, was prepared with the aim of capturing carbon dioxide. Polyaniline was synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate and subsequently used for modification of the aramid surface. The prepared polyaniline/aramid composite was characterized using electrokinetic analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption isotherms for determination of specific surface area and porosity and using carbon dioxide adsorption/desorption isotherms for determination of carbon dioxide capture. The capture capacity markedly increased from 22 cm3 g−1 for pristine aramid to 60 cm3 g−1 for the polyaniline/aramid composite. The results show that the new composite material could be used as an effective adsorbent of carbon dioxide and for applications based on its adsorption. The vision of advanced adsorbents with properties controlled by electric potential applied to conducting polymers is worth being considered. © 2023 Society of Industrial Chemistry.

SYNTHESIS AND CHARACTERIZATION NOVEL EMERALDINE-SALT@PORANGCOMPOSITES THIN FILM:CONDUCTIVITY STUDIES

A synthesis of the emeraldine salt@porangcomposite was synthesized using the in situ chemical polymerization method to form the ES@Porang composite. Polymerization using ammonium peroxodisulphate as an initiator in the aniline oxidative polymerization process and using H2SO4 doping. The composite films were prepared with variations in dopant concentration and variations in the amount of glucomannan. Characterization of the ES@Porang composite using FTIR and conductivity testing using an LCR-meter. The optimum conductivity values ​​of the ES@Porangcomposite thin film with variations in dopant concentration and amount of glucomannan were 24.3 x 10-3, 58.2 x 10-3, and 84,3 x 10-3 S/cm respectively.

Design and Characterization of Nanostructured Titanium Monoxide Films Decorated with Polyaniline Species

The fabrication of nanostructured composite materials is an active field of materials chemistry. However, the ensembles of nanostructured titanium monoxide and suboxide species decorated with polyaniline (PANI) species have not been deeply investigated up to now. In this study, such composites were formed on both hydrothermally oxidized and anodized Ti substrates via oxidative polymerization of aniline. In this way, highly porous nanotube-shaped titanium dioxide (TiO2) and nano leaflet-shaped titanium monoxide (TiOx) species films loaded with electrically conductive PANI in an emeraldine salt form were designed. Apart from compositional and structural characterization with Field Emission Scanning Electron Microscopy (FESEM) and Raman techniques, the electrochemical properties were identified for each layer using cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Based on the experimentally determined EIS parameters, it is envisaged that TiO-based nanomaterials decorated with PANI could find prospective applications in supercapacitors and biosensing.

Wearable Conductive Polymer Matrix Composites for Breath Monitoring with Ammonia Detection

Conductive polymers, such as polyaniline (PANI), Polythiophene (PTh), polypyrrole (PPy), etc., are widely used for gas sensors due to their excellent electrical conductivity and low cost to manufacture [1]. In particular, PANI has attracted more attention due to its ease of synthesis, high environmental stability, and high reactivity with ammonia gas. In addition, the selection of acid-base dopant during the preparation process of polyaniline can adjust carrier concentrations for the change in electrical conduction or resistance to improve sensing properties. There have been many reports on the fabrication of flexible gas sensors using PANI [2-4]. Bandgar et al. [5] synthesized a low-temperature flexible polyaniline gas sensor by in-situ chemical oxidation polymerization of aniline on a polyethylene terephthalate (PET) substrate, showing 99% reproducibility, rapid response and recovery. Still, the response value was only 26% in 100 ppm ammonia atmosphere. Qi et al. [6] prepared a gas sensor by in-situ polymerization of aniline on non-woven fabric. The high air permeability of the fabric effectively improved the performance of the polyaniline-based gas sensor. Due to the outbreak of the COVID-19 pandemic, the use of face masks in public has become essential to reduce the spread of the virus. Some reports claim that the increased carbon dioxide in the mask over time may cause medical issues related to the respiratory system. Therefore, monitoring breathing air quality can help detect the wearer's vital conditions.In this study, we used a disposable mask as a flexible substrate to prepare polypropylene/carbon nanotube/polyaniline composite film through a layer-by-layer method. The polypropylene/carbon nanotube composite films were prepared by applying the carbon nanotube aqueous solution with surfactants evenly on the surface of a mask filter layer by a drop-coating method. Then, the in-situ polyaniline polymerization was performed on the surface of the polypropylene/carbon nanotube composite film through ammonium sulfate. The polypropylene/carbon nanotube /polyaniline composite film exhibits high sensitivity, fast sensing response/recovery time, room temperature operation, reliable flexibility, and cycle stability. The synthesized and wearable masks have demonstrated real-time detection respiratory rate and other breathing conditions such as CO2 and humidity. The ammonia gas sensing can also be used as a potential biomarker for health screening. The design and integration of multiple gas sensing materials in masks will help wearers better understand their own body conditions.

DOPANT, IMMERSION TIME EFFECT, AND HYDROLYSIS ONTO POLYANILINE/BACTERIAL- COMPOSITES: CONDUCTIVITY STUDIES

The composite of conductive polyaniline was synthesized using the in situ chemical polymerization methods on cellulose to form PANI-cellulose composites. Polyaniline can be composited with a cellulose matrix (nata de coco) due to its abundance, low price, and environmental friendliness. Ammoniumperoxodisulfate (APS) was used as an initiator forthe oxidative polymerization of aniline. Characterization of PANI-Cellulose Bacterial composite was drawn using FT-IR and SEM, while the conductivity and electric quantities both using LCR-meter, FT-IR spectra, and SEM The PANI-cellulose bacterial composite with the various concentration dopant of H2SO4 methods has the highest conductivity than PANI-cellulose bacterial composite with the dopant of HCl methods.

Investigation of intelligent protection and corrosion detection of epoxy-coated St-12 by redox-responsive microcapsules containing dual-functional 8-hydroxyquinoline

Smart coatings with self-healing capabilities have frequently been made using microcapsules. Incorporating bifunctional materials as a self-healing agent into microcapsules allows for the early detection of corrosion before substantial damage to the metal surface occurs. In this study, the oxidative polymerization of aniline in the direct miniemulsion method was used to synthesize polyaniline (PANI) microcapsules. The corrosion inhibitor 8-hydroxyquinoline (8-HQ) was used in the core of microcapsules, which can also act as a fluorescent indicator of iron ions. The synthesized microcapsules were characterized by Optical Microscopic (OM), Field Emission Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared (FTIR), Ultraviolet-Visible (UV–Vis), and Dynamic Light Scattering (DLS) techniques. The corrosion resistance behavior and self-healing performance of 8-hydroxyquinoline loaded polyaniline microcapsules into epoxy coating were investigated by Electrochemical Impedance Spectroscopy (EIS), and standard salt spray test. It was found that the epoxy coating containing 5 wt% of the polyaniline microcapsules with 1000 ppm of encapsulated 8-hydroxyquinoline exhibited better corrosion protection performance with an impedance value of 1.54 × 108 Ω.cm2 at low frequency (0.01 Hz) out of all the samples after 10 weeks immersion in electrolyte with a concentration of 3.5 wt% NaCl. Additionally, the evaluation of the release of 8-hydroxyquinoline from microcapsules in a damaged area is characterized by Inductively Coupled Plasma (ICP) spectrometer and fluorescence microscope. The synergistic effects of polyaniline microcapsules and the 8-hydroxyquinoline healing agent are thus responsible for the coatings' self-healing abilities. The study's findings revealed that the dual-functional 8-hydroxyquinoline is successfully released from the microcapsules and acts as a fluorescent indicator and corrosion inhibitor by detecting corrosion at the early stages.

Fabrication of electrospun polyetherimide/polyaniline self-supporting microfiber membranes as electrodes for flexible supercapacitors via in-situ polymerization

The intrinsic properties and structural construction of active materials are crucial to improving the performance of electrodes. Herein, flexible and hydrophilic polyetherimide/polyaniline (PEI/PANI) conductive microfiber membranes with unique core-shell architecture were prepared via electrospinning followed by in-situ chemical oxidation polymerization of aniline doped with 2-acrylamido-2-methyl-1-propanesulfonic acid, and used to boost the properties through the combined action of the pseudocapacitive PANI and abundant porous PEI membranes. For achieving excellent PEI/PANI microfiber membranes as free-standing electrodes, the polymerization time was controlled to refrain from exceed PANI particles agglomeration and maintain the unique three-dimensional porous network structure. Optimized PEI/PANI microfiber membranes with the polymerization time of 7 h presented the best electrochemical properties with high specific capacitance of 249.5 F g−1 at 1 A g−1 and low charge-transfer resistance of 8.316 Ω. Ascribing to the combined effect between the unique pore structure of PEI microfiber membranes and pseudocapacitance of PANI, the flexible supercapacitor based on PEI/PANI-7 demonstrated exceptional capacitance (175.1 F g−1 at 1 A g−1), high energy density (43.4 Wh kg−1) and power density (34.0 kW kg−1), and outstanding flexibility while preserving the cyclic stability. Therefore, this free-standing PEI/PANI microfiber membranes could be deemed as a prospective electrode contender for flexible supercapacitor applications.

Polyaniline-Based Rose-like Chiral Nanostructures for Raman Enhancement

Metal-free materials for efficiently enhancing Raman spectrum represent a Frontier in the field of Raman enhancement. Herein, a metal-free Raman enhancement-active material, polyaniline (PANI)-based rose-like chiral nanostructures, which is fabricated by the oxidation polymerization of aniline occurred in a reaction droplet on a glass slide, is developed. The morphology of the as-prepared PANI nanostructures is well designed to rose-like chiral (left-handed or right-handed) nanostructures. Due to the suitable energy level and chiral nanostructure feature, the prepared PANI nanostructures exhibit excellent Raman enhancement performance compared with other metal-free materials. The enhancement factors of the chiral nanostructures are 10 times more than that of achiral nanostructures for dye molecules (e.g., 22.5 times for crystal violet), indicative of significance of the chiral nanostructure to the macroscopic performance. Moreover, the superior reproducibility and generality of the PANI-based rose-like chiral nanostructures illustrate its high potential in Raman enhancement applications. This work not only provides an efficient metal-free platform for Raman enhancement but also develops herein the idea, which is highly instructive for the rational design of advanced Raman enhancement-active materials for broader applications.

Hierarchical construction of reduced graphene oxide-polyaniline-NiMoS4 phases to enhance the asymmetric supercapacitor capacity

The ternary reduced graphene oxide (rGO)/polyaniline (PANI)@NiMoS4 composite with the three-dimensional hierarchical structure was constructed by the in-situ chemical oxidation polymerization of aniline on GO surface, followed by the hydrothermal treatment. The grafted PANI cannot only provide the additional Faradaic redox reaction, but also support the rGO and NiMoS4, alleviating the self-stacking phenomenon for many ion transfer channels. The optimized rGO/PANI@NiMoS4 exhibits the high specific capacity of 194 mAh/g at 0.75 A/g. Meanwhile, the corresponding rGO/PANI@NiMoS4//AC asymmetric supercapacitor also exhibits the high energy density of 30.75 Wh/kg at 1500 W/kg, and good cycle stability with capacity retention of 93 % after 6000 cycles. These satisfactorily electrochemical performances of rGO/PANI@NiMoS4 composites reveal the potential supercapacitor application. This work provides an efficient way to increase the capacity of NiMoS4 related electrode materials.