Self-doped Polyaniline Research Articles

Amperometric Signal Generation by Self-Doped Polyanilines for Ion-Selective Electrodes

Amperometric Signal Generation by Self-Doped Polyanilines for Ion-Selective Electrodes

Proton Self-Doped Polyaniline with High Electrochemical Activity for Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries are promising energy storage devices due to their low cost, good ionic conductivity, and high safety. Conductive polyaniline is a promising cathode because of its redox activity, but because the neutral electrolyte protonates only weakly, it displays limited electrochemical activity. A polyaniline cathode is developed with proton self-doping from manganese metal-organic frameworks (Mn-MOFs) that alleviates the deprotonation and electrochemical activity concerns arising during the charge/discharge process. The MOFs carboxyl group provides protons to prevent deprotonation and allows the polyaniline to reach a high zinc storage redox activity. The proton self-doped polyaniline cathode has a superior specific capacity (273mAhg-1 at 0.5Ag-1 ), a high rate property (154mAhg-1 at 20Ag-1 ), and excellent cyclability retention (87% over 4000cycles at 15Ag-1 ). This research provides fresh insight into the development of innovative polymers as cathode materials for high-performance AZIBs.

Highly conductive and mechanically strong metal-free carbon nanotube composite fibers with self-doped polyaniline

Individual carbon nanotubes (CNTs) have gained popularity as lightweight wire materials due to their high electrical conductivity and low density than that of copper wires. Despite intensive research on light-weight and highly conductive CNT fibers, the bulk properties of CNT assemblies are inferior to those of metal wires in terms of electrical conductivity. Herein, we propose a method to increase the specific electrical conductivity of CNT fibers with polyaniline (PANI). The structure and physical properties of the CNT fibers are precisely controlled by optimizing the PANI content through a simple and effective solution process. PANI is considered to enhance CNT orientation, decrease voids, and dope the CNT fibers, resulting in a better electron flow in the fibers. The developed composite fiber with 5 wt% PANI demonstrated remarkable specific electrical conductivity of 6,200 ± 160 S m2/kg (11.9 MS/m) (max: 6,360 S m2/kg), an improvement of 16% above as-spun CNT fiber. Simultaneously, the mechanical properties increased by 27%, yielding a high specific tensile strength of 2.63 ± 0.10 N/tex (5.05 GPa). Furthermore, the toughness improved to 79.5 J/g, approximately a 1.8 times improvement over that of the CNT fiber. The addition of a small amount of PANI to CNT fibers has led to significant improvements in electrical and mechanical properties, which can provide insights into research on the CNT fiber field.

Efficient removal of safranin from aqueous solution using a new type of metalated highly self-doped polyaniline nanocomposite

We report the chemical synthesis of poly(aniline-co-aniline-2,5-disulfonic acid)) and its composite containing L-hexuronic acid and metallic Ag/SiO2 nanoparticles as a new thermally stable anionic polyelectrolyte for removing safranin dye. The composite was characterized by IR, UV, cyclic voltammetry, SEM, TEM, TGA, DSC, EDXS and elemental analyses. Microscopic images exhibited intensified spherical particles dispersed over almost the entire surface. The XRD exhibited peaks of the partially crystalline material at many 2θ values, and their interatomic spacing and sizes were calculated. The cyclic voltammograms exhibited characteristic redox peaks relative to the quinoid ring transition states. The uptake rates up to 82.5% adsorption were completed within 75 min and the equilibrium time was 45 min. The isotherm of dye adsorption interprets the interaction with the adsorbent and explain the relationship between the dye removal capacity and the initial dye concentration. In the current, the Langmuir isotherm model was the optimum to interpret both the dye/copolymer and the dye/composite interactions. The uptake of safranin by copolymer/SiO2@Ag nanocomposite was well defined by pseudo second order model with rate constant K2 = 0.03 g− 1 mg− 1 min− 1 for 19 mg safranin. A comparison of safranin adsorption efficiency of the synthesized material with other reported material in the same domain suggested that the present composite has a higher adsorption rate and capacity. The ongoing research is devoted to improving the removal percentage of the dye by using 1,3,5-triazine based sulfonated polyaniline/Ag@ SiO2 nanocomposite.

A thixotropic molecular hydrogel composite composed of polymer hydrogelator and self-doping polyaniline copolymer for electrochromic and glucose sensing applications

An electrochemically active, paintable, thixotropic molecular hydrogel was created by mixing a polymer hydrogelator and polyaniline copolymer, and the gels were used to create electrochromic and glucose-sensing properties.

High performance of chemically-modified graphene-based supercapacitor using an effective redox active binder

A robust combination of two redox-active materials consisting of self-doped polyaniline (SPAN)–based covalently bonded 4-aminobenzoic acid-bonded graphene (ABG) and a polyamide binder is proposed to promote supercapacitor performance. This strategy for improving the electrode capacity involves bonding SPAN onto a ABG with a high specific surface area. A SPAN-ABG material is formed and polycondensation is applied to 1,5-diaminoanthraquinone (DAQ) and 4,4′-oxydibenzoic acid (DBA), producing a DAQ-DBA polyamide binder with a Faraday effect on charge storage. SPAN-ABG and DAQ-DBA are combined to fabricate supercapacitor electrodes. At a charging-discharging current density of 1 A/g, the supercapacitor capacitance value (550 F/g) of SPAN-ABG (DAQ-DBA) electrode is higher than that (350 F/g) of SPAN-ABG (PVDF) electrode. After testing for 5000 cycles at a current density of 1 A/g, this supercapacitor has charging–discharging capacitance retention of 98.2 %, which is higher than that of supercapacitors with a PVDF binder (97.8 %). The results confirm that these electrode materials fabricated using both redox-active materials of SPAN-ABG and polyamide binder can synergistically enhance supercapacitor performance.

A New Composite of O-aminobenzene Sulfonic Acid Self-Doped Polyaniline and Multi-Walled Carbon Nanotubes as a Fiber Coating for Solid-Phase Microextraction Gas Chromatography

A New Composite of O-aminobenzene Sulfonic Acid Self-Doped Polyaniline and Multi-Walled Carbon Nanotubes as a Fiber Coating for Solid-Phase Microextraction Gas Chromatography

Shape-Dependent Conduction Regime in Self-Doped Polyaniline

Shape-Dependent Conduction Regime in Self-Doped Polyaniline

High performance in-situ tuned self-doped polyaniline (PANI) membranes for organic solvent (nano)filtration

Cross-linked polyaniline (PANI) membranes are attractive for organic solvent nanofiltration (OSN). However, inadequate tuneability to cover the full nanofiltration (NF) separation range, prolonged post-treatment cross-linking using hazardous organic chemicals and poor permeance limit their widespread application. This work introduces a new strategy to tune the transport properties of PANI membranes to suit the rejection spectrum of NF membranes without compromising permeance. Incorporating different molecular weight organic acids, metanilic acid (MA) and poly (2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA), facilitated cross-linking during polymer precipitation at different aqueous coagulation bath acidic strength using non-solvent induced phase separation (NIPS). Static ageing tests for PANI membranes immersed in tetrahydrofuran (THF) for 30 days showed no physical or chemical deterioration. All membranes were stable during long-term dynamic crossflow filtration tests over 250 h with sequential feed of methanol, acetonitrile and THF. THF permeance was 2.1–16.4 L m−2 h−1 bar−1 with apparent molecular weight cut off (MWCO) between 250 and 1000 g mol−1. PAMPSA doped membranes were successfully cross-linked but required wet annealing post-treatment to obtain membranes in NF range. The MA doped membranes surpassed the performance of cross-linked PANI membranes with glutaraldehyde (organic cross-linker) showing a 2.5 times higher permeance with better rejection. In comparison to commercial polyimide membranes, PANI membranes prepared in coagulation bath ≥0.5 M HCl(aq) were stable in N,N-dimethylformamide (DMF) whereas the former suffered complete damage. This work represents a simplified technique to in-situ optimise permselective properties of OSN self-doped PANI membranes for various applications in food, pharmaceutical and petrochemical industries.

A high-performance covalently bonded self-doped polyaniline–graphene assembly film with superior stability for supercapacitors

In this study, a robust high-performance polyaniline-modified graphene electrode is successfully used to assemble a supercapacitor. Graphene is covalently bonded to self-doped polyaniline (SPANI) and used in supercapacitors, and 4-aminobenzoic acid-modified graphene (ABF-G) sheet materials are first bonded to an aniline functional group at graphene edges. Then, aniline, o-aminobenzene sulfonic acid monomers, and an oxidising agent are added into the ABF-G aqueous dispersion to achieve polymerisation on the surface of ABF-G. This covalently bonded SPANI-modified ABF-G (SPANI-ABF-G) thin-film electrode material is then used for fabricating supercapacitors. A Raman spectrometer, a scanning electron microscope, a secondary ion mass spectrometer, an X-ray electron photon spectrometer, and a specific surface area analyser are used to characterise this film. The supercapacitor with the proposed SPANI-ABF-G electrodes exhibits a high specific capacitance value of 642.6 F/g for charging and discharging at a current density of 1 A/g. After 5000 cycle-life testing, this supercapacitor exhibits a charging and discharging capacitance retention of 100% and 98.13% at a current density of 1 and 2 A/g, respectively. These capacitance retentions are higher than those of supercapacitors with conductive polymers electrodes. The results prove that electrode materials prepared using covalently bonded graphene and PANI can considerably improve supercapacitor performance.

Homogeneous chemical state of self-doped polyaniline sub-micrometer thickness lines fabricated by fountain-pen lithography

The fabrication of molecular films by coating a conductive polymer solution on a substrate is an active topic in molecular electronics research. Since the inhomogeneity of polymer thin films modulates the chemical states and electrical properties of these films, the construction of integrated polymer devices requires methods to fabricate controllable, homogeneous molecular films as small patterns. Herein, we report the reproducible fabrication of sub-micrometer thickness self-doped polyaniline lines with high homogeneity by fountain-pen lithography (FPL). Compared with commonly used drop-casting and spin-coating methods, the fabrication of line patterns by FPL allows good control of line size, chemical/micro structures, and electronic properties, as demonstrated here by microscope Raman spectroscopy and conductance measurements. Supplying an identical amount of solution from a nanopipette and rapid solvent evaporation are likely crucial for fabricating homogeneous line patterns. This method is promising for the development of molecular electronic devices and the characterization of polymeric materials.

Comparative study on anticorrosion enhancement of carboxylated and sulfonated self-doped polyaniline on waterborne epoxy coating

Water-dispersed self-doped sulfonated polyaniline (SPANi) and self-doped carboxylated polyaniline (CPANi) were prepared by the copolymerization of aniline with m-aminobenzenesulfonic acid and m-aminobenzoic acid, respectively, and were identified by UV-vis spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and scanning electron microscopy. The resultant SPANi and CPANi nanofibers were used as anticorrosion pigments for water epoxy coatings (EP). The corrosion resistance was compared using anticorrosive studies in 3.5 wt% NaCl solution using electrochemical impedance spectroscopy (EIS), polarization curves (Tafel), and a neutral salt spray (NSS) test. Polarization tests showed that the corrosion potential of SPANi/EP coating increased compared with CPANi/EP. EIS tests after 40-day immersion. This behavior further confirmed that the impedance modulus and coating resistance of SPANi/EP increased by three orders of magnitude compared with EP, which were two orders of magnitude higher than that of polyaniline (PANi)/EP and one order of magnitude higher than that of CPANi/EP.

Local-field-induced current noise in shape-limited self-doped polyaniline

Electronic noise generators are an essential component of molecular neuromorphic devices. To realize molecular noise generators with a high degree of freedom for design and integration into molecular devices, the utilization of the local electric field for the modulation of electrical conduction via a shape-limited conductive polymer is one promising strategy. Herein, a molecular noise generator composed of thin self-doped polyaniline (SPAN) lines is reported. SPAN lines fabricated via fountain pen lithography on SiO2/Si substrates were found to generate current noise upon laser irradiation. This current noise exhibited white-noise-like power spectral density in the frequency range of 1–25 Hz and was independent of temperature. Multiple independent noise generation on the same substrate was also successfully demonstrated. The present results indicate that the noise generation mechanism involves the local modulation of hopping conduction via SPAN lines owing to the spatial proximity of the conduction path in the SPAN line to the surface photovoltage region of the SiO2/Si interface. This on-site random noise generation in shape-limited conductive polymers is expected to be beneficial for the realization of molecular neuromorphic devices.

Electrochemically imprinted self-doped polyaniline as highly sensitive voltammetric sensor for determination of bismuth in water, wastewater, and pharmaceutical samples

A novel electrochemically imprinted self-doped polyaniline (SDPAn) film-modified glassy carbon electrode (GCE) for bismuth ion (Bi3+) determination was prepared here based on copolymerization of polyaniline with metanilic acid, GCE/P(An-co-MA). Firstly, prepared SDPAn was characterized by using solid-state UV–visible, SEM, and EDXA techniques. Then, the GCE/P(An-co-MA) electrode was templated by several consecutive reduction/oxidation potential steps in Bi3+ solution for improving its selectivity to Bi3+ ions. Affecting parameters on detection signal like MA concentration, pH, and time in polymerization step and preconcentration potential and incubation pH in preconcentration step have been optimized by means of experimental design. The differential pulse anodic striping voltammetric signal of the GCE/P(An-co-MA) in optimized conditions was recorded and a linear relation ship from 1.0 × 10−9 to 1.0 × 10−4 M of Bi3+, R2 as 0.9960, with detection limit as 0.48 nM Bi3+, and RSD as 1.49% was obtained. This sensor was successfully applied for voltammetric determination of Bi3+ ions in water, wastewater, and pharmaceutical samples.

A flexible, electrochromic, rechargeable Zn-ion battery based on actiniae-like self-doped polyaniline cathode

A flexible, electrochromic, rechargeable Zn-ion battery, with a monitoring function of the energy storage according to color variation, has been prepared and characterized.

Multimodal cellular redox nanosensors based on self-doped polyaniline nanocomposites.

We have successfully fabricated a nanocomposite, which is composed of polyaniline (PAni) and pyrene butyric acid (Pyba) via a solvent shift method, which was self-doped at a neutral pH value. This PAni nanocomposite can act as a fine nanoagent expressing absorbance, fluorescence, and Raman properties according to the surrounding pH values.

Electrochemical Sensor Based on Self-doped Polyaniline with Guest-induced Binding Sites for Detection of Lead(II) Ion

Electrochemical Sensor Based on Self-doped Polyaniline with Guest-induced Binding Sites for Detection of Lead(II) Ion

Conjugated System of PEDOT:PSS-Induced Self-Doped PANI for Flexible Zinc-Ion Batteries with Enhanced Capacity and Cyclability.

Owing to its electronic conductivity and electrochemical reactivity, polyaniline (PANI) can serve as the cathode for rechargeable zinc-ion batteries (ZIBs). However, it suffers from fast deactivation and thus performance deterioration because of spontaneous deprotonation during charge/discharge. Here, we report an effective strategy to improve the electrochemical reactivity and stability of the PANI-based cathode by constructing a π-electron conjugated system between PANI and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) on carbon nanotubes (CNTs). The impressive performance of the post-treated CNTs-PANI-PEDOT:PSS (t-CNTs-PA-PE) cathode is largely attributed to the -SO3-H+ groups in PSS, which acts as an internal proton reservoir and provides enough H+ for PANI's protonation, thus promoting its electrochemical activity and reversibility. Besides, the strong interactions between PANI and PEDOT:PSS assist the stretching of π-π conjugation chains, bringing about enhanced electronic conductivity. Consequently, the t-CNTs-PA-PE cathode achieves a high capacity of 238 mA h g-1, together with good rate capability and long-term stability (over 1500 cycles with 100% Coulombic efficiency). Through exerting the freestanding t-CNTs-PA-PE, a flexible ZIB was further constructed with both outstanding electrochemical properties and superior high safety. This work demonstrates the availability of conducting polymer cathodes for high-performance ZIBs, fulfilling the need of flexible electronics.

A Self-Doped Polyaniline Cathode for Rechargeable Aqueous Zinc Batteries

Rechargeable batteries offer promising solutions to the energy shortage issue.[1] In comparison to non-aqueous Li-ion batteries, aqueous rechargeable batteries possess the merits of using low-cost and high-safety water-based electrolytes. Aqueous electrolytes also provide higher ionic conductivities than non-aqueous ones, which promotes better rate performance of the cell.[2] These superiorities make the system suitable for stationary grid-level energy storages. The zinc metal is a convenient anode for aqueous batteries due to its low redox potential (-0.76 V vs. standard hydrogen electrode), high theoretical capacity (5845 mAh cm-3, 819 mAh g-1) and good compatibility with water.[3]-[5] Its abundant earth storage, non-toxicity and stability in air furthermore benefits large-scale productions. Using neutral or slightly acidic solutions to replace the alkaline electrolytes can suppress the dendritic growth of Zn anode.[4] One urgent requirement of zinc battery research is to find a suitable cathode. Benefiting from the long π-electron conjugated systems, conducting polymers hold higher conductivities compared to metal oxides and organic materials.[6] The highly conductive polyaniline (PANI) is a potential cathode, but it tends to deactivate in low acidic electrolytes (i.e. pH > 1) due to the de-protonation of the polymer. Herein, we synthesized a sulfo self-doped PANI electrode by a facile electrochemical copolymerization process. The -SO3 - self-dopant functions as an internal proton reservoir to ensure locally high acidic environment and facilitate the redox process in the weak acidic ZnSO4 electrolyte. In a full zinc cell, the self-doped PANI cathode delivers a high capacity of 180 mAh g-1, excellent rate performance of 70% capacity retention at 50 times current density increase, and long cycle life of over 2000 cycles with coulombic efficiency close to 100%. The detailed charge storage processes were investigated by X-ray photoelectron spectroscopy and X-ray diffraction. They suggest partial proton insertion into self-doped PANI during discharge, which leads to the internal protonation of -N= units and facilitates further reduction. This helps the polymer to maintain high electrochemical activity and stable capacity retention over cycling, in direct contrast to the fast capacity decay with the non-self-doped PANI cathode. Overall, our work utilizes the smart pH adjustment ability of self-dopants to overcome the discrepancy of active conditions between PANI cathode and Zn anode. More importantly, it demonstrates the potential applications of conducting polymers as cathode materials for rechargeable zinc batteries, with the specific energy storage behavior tunable thanks to the rich chemistry of their family.

Core-Shell Self-Doped Polyaniline Coated Metal-Organic-Framework (SPAN@UIO-66-NH2) Screen Printed Electrochemical Sensor for Cd2+ Ions

Cadmium ions have variable degrees of toxicity on the environment and organisms. An electrochemical sensor based on self-doped polyaniline (SPAN) modified Metal-organic Framework (SPAN@UIO-66-NH2) with high electron mobility was developed. Cyclic voltammetry and electrochemical impedance spectroscopy indicated that doping of SPAN enhanced the electron transfer rate of UIO-66-NH2 in SPAN@UIO-66-NH2. The optimized Cd2+ sensor exhibited good linear response from 0.5 μg L−1 to 100 μg L−1, low detection limit of 0.17 μg L−1 (based on S/N = 3), good stability, and fast response time. It showed decent reliability for detection of trace Cd2+ in natural lake and urine samples.