Polyaniline Electrode Research Articles

Polyaniline/fullerene derivative nanocomposite for highly efficient supercapacitor electrode

The effect of intercalation of fullerene derivative Phenyl-C60-butyric acid methyl ester (PCBM) into polyaniline (PANI) matrix with different ratio is reported. The PANI/PCBMx (where x = 0, 2.5, 5 and 10) nanocomposites are characterized by UV-VIS spectroscopy, Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray diffraction spectroscopy (XRD). The results confirm that the PANI/PCBM nanocomposites are synthesized successfully. The prepared nanocomposites are cast onto Nickel foam as a current collector and tested as a supercapacitor electrode in 2 M KOH electrolyte using cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD). The effect of different current collector substrates including stainless steel, nickel metal and graphite sheet on the supercapacitor performance is compared. The electrochemical measurements show an improvement by more than two times in the specific capacitance of PANI/PCBM5 electrode compared to pure PANI electrode. It is found that, the specific capacitance is 2201 F/g at a current density of 2 A/g with a good rate capability of about 73% at 10 A/g. The energy and power densities of PANI/PCBM5 electrode are 61.9 W h/Kg and 2250 W/Kg, respectively. Furthermore, the PANI/PCBM5 electrode shows an excellent cycling stability with 96% of the capacity retention after 1000 cycles.

Boosting the electrochemical properties of polyaniline by one-step co-doped electrodeposition for high performance flexible supercapacitor applications

A facile one-step co-doped electrodeposition method is proposed to prepare polyaniline (PANI) electrodes with improved supercapacitive properties. During electrodeposition of PANI films, sulfuric acid and perchloric acid simultaneously act as dopants to obtain sulfuric acid and perchloric acid co-doped PANI (SP-PANI) electrode. For comparison, single-doped PANI (i.e., sulfuric acid-doped PANI (S-PANI) and perchloric acid-doped PANI (P-PANI)) electrodes are prepared with the same electrodeposition parameters. Electrochemical measurements indicate that the SP-PANI electrodes exhibit substantially improved electrochemical capacitive properties with respect to single-doped PANI electrodes. This improvement can be attributed to the fact that the co-doping changes the morphology, electrical conductivity, and roughness of the PANI films electrodeposited, thus leading to easy pathway for electron transport and increased electroactive surface area. Moreover, we have demonstrated the feasibility of SP-PANI electrodes for use in high performance flexible solid-state supercapacitors. The assembled supercapacitor with SP-PANI electrodes shows high areal capacitance of 149.3 mF cm−2 at 0.5 mA cm−2. It also features high mechanical flexibility, good electrochemical capacitive properties, and superior deformation and electrochemical stability, making it have high application potential in flexible electrochemical energy storage.

Facile fabrication of polyaniline films with hierarchical porous networks for enhanced electrochemical activity

This paper describes a facile method for fabricating polyaniline (PANI) films with well-defined three-dimensional (3D) porous networks and improved electrochemical activity. The PANI hydrogel pastes with different compositions are directly cast into thin films by the doctor blade technique. After a dehydration step, the conductivity of the PANI drastically increases, while the porous structure with hierarchical macro- and meso-porosity is formed in the PANI film. The electrical conductivity tends to increase with the thickness of the porous PANI film until it fails to form a mechanically stable film not exhibiting cracking problems. We found that the amount of the initiator, the aniline monomer, and the crosslinker significantly affect not only the micro-morphology of PANI films, but also their electrical and electrochemical characteristics. Importantly, when the amounts of the crosslinker and the initiator increase, the polymer film forms with a dense internal morphology with smaller pores. Based on the engineered synthesis composition, we demonstrate a supercapacitor with porous PANI electrodes. Due to the hierarchical porous structure, large surface area and the improved conductivity, the resulting devices show excellent volumetric capacitances, which are comparable to or much higher than those previously reported.

A Low-Cost Paper Glucose Sensor with Molecularly Imprinted Polyaniline Electrode.

For the hundreds of millions of worldwide diabetic patients, glucose test strips are the most important and commonly used tool for monitoring blood glucose levels. Commercial test strips use glucose oxidases as recognition agents, which increases the cost and reduces the durability of test strips. To lower the cost of glucose sensors, we developed a paper-based electrical sensor with molecularly imprinted glucose recognition sites and demonstrated the determination of various glucose concentrations in bovine blood solutions. The sensing electrode is integrated with molecular recognition sites in the conductive polymer. A calibration graph as a function of glucose concentration in aqueous solution was acquired and matched with a correlation coefficient of 0.989. We also demonstrated the determination of the added glucose concentrations ranging from 2.2 to 11.1 mM in bovine blood samples with a linear correlation coefficient of 0.984. This non-enzymatic glucose sensor has the potential to reduce the health care cost of test strips as well as make glucose sensor test strips more accessible to underserved communities.

Smart Electrochromic Supercapacitors Made of Metal Mesh Electrodes with Polyaniline as Charge Storage Indicator

Herein, the design and fabrication of a smart electrochromic supercapacitor using Au mesh and polyaniline (PANI) electrodes is reported. The Au mesh is obtained through the crackle templating method, whereas PANI is brought in by electrodeposition. The device exhibits a high capacitance of ≈15 mF cm−2 with good charge–discharge cycling stability. What is attractive about this device is that it can switch its color rapidly to yellow, green, or blue, depending on the operable voltage window that should serve to indicate the level of energy stored in the supercapacitor, visually.

Rational-design of polyaniline cathode using proton doping strategy by graphene oxide for enhanced aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) have been of excellent interest in the latest years due to their environmental benignity and easy preparation. One vital barrier to the production of high-performance ZIBs is the development of appropriate cathode materials. Polyaniline (PANI) is very promising, particularly due to its excellent conductivity and easy preparation, among varied cathode materials. However, deprotonation of PANI is a key problem greatly deteriorating capacity and cycling stability of PANI cathode. In this study, we discover that graphene oxide (GO) can fix the problem effectively as the wealthy functional GO oxygen groups can provide a local proton reservoir that increases PANI protonation. As a result, the GO composited PANI electrodes show significantly improved zinc-ion storage performance than pure carbon composited PANI cathodes. Specifically, the battery performances in terms of capacity (233 mA h g−1) and rate performance (100 mA h g−1 under 5 A g−1) are enhanced significantly after introducing GO into PANI cathode. Besides, flexible PANI-based ZIB devices can be easily fabricated owing to the excellent film-forming property of GO. This work offers new insight for improving PANI cathode materials by carbon chemistry.

Roles of TiO2 in the highly robust Au nanoparticles-TiO2 modified polyaniline electrode towards non-enzymatic sensing of glucose

Along with the rise of diabetes mellitus issue, glucose sensor has become an imperative tool for healthcare. Studies have been widely conducted on electrode materials for glucose sensors; metal nanoparticles and/or oxide particles in its nano-size are reported to exhibit remarkable electrocatalytic activities in the non-enzymatic glucose sensors. However, the decoration processes of metal nanoparticles or nano-sized oxides are known to be tedious and time-consuming. In addition, the processes usually result in great amount of waste solution emission. In this study, therefore, an Au nanoparticles (NPs)-TiO2 modified polyaniline (PANI) composite is practiced towards the applications of non-enzymatic glucose sensors, by using a facile and time-saving thermal reduction and by electrodeposition techniques with low waste solution emission. Au NPs, which is modified with TiO2 nanoparticles in its optimized amount, performs the highest electrocatalytic activity to the oxidation of glucose in alkaline solution. The stability of Au NPs-TiO2/PANI is superior to those of most reported results over 70 days. The sensitivity and detection limit are 379.8 μA mM−1 cm−2 and 0.15 μM, respectively. High selectivity of Au NPs-TiO2/PANI is also confirmed by the interference test. Spill-over effect of OH− between Au NPs and TiO2, which is the main reason for the improved catalytic activity, is described in this study.

Potentiometric detection of copper ion using chitin grafted polyaniline electrode

Potentiometric detection of copper ion over chemically interactive and electrically responsive chitin grafted polyaniline (Chit-g-PANI) electrode has been demonstrated for natural as well as artificial samples under optimized conditions using a portable sensing setup. The physical properties and chemical structure of developed electrode were evaluated by different Infrared spectrometry, X-ray diffraction, scanning electron microscope, thermal gravimetric analyzer and ASTM methods. The result indicates the formation of electrically responsive, chemically interactive, stable grafted hybrid matrix for durable and reproducible potentiometric electrode for a self-designed portable potentiometric cell. The potentiometric response of electrode toward Cu2+ ions follows the nernst relation in the range from 1 to 103 ppm with detection limit of 13.77 ppm and negligible interference for different co-existing cations and anions. Further, on the basis of interaction between cupric ion and Chit-g-PANI matrix, the sensing mechanism and ion to electron transduction has been discussed along with future prospects for on-site applications.

Effect of drying temperature on polyaniline electrode for polyaniline|Zn battery performance

ABSTRACT . Here, we report the effect of various drying temperature of Polyaniline (PAni) on battery PAni|Zn performance. PAni was synthesized using the electrodeposition method on the surface of the graphite sheets (GS), at 0.7 V relative to the saturated Ag/AgCl. PAni is dried with various temperature, 25, 80, 120, and 180 o C, respectively. PAni was characterized by Raman spectroscopy; then the performance Pani battery was studied in a rechargeable battery system. The measurement results found the PAni|Zn battery with 25 o C temperature drying of PAni was a good performance which the capacity density stable at 175–105 mAh g -1 until 100 cycles. Raman study showed that high-temperature drying resulted in a cleavage peak at 1188 cm -1 and increased peak intensity at 1495 cm -1 . This vibrational mode appears as a stretching ν(C-C) on the semi quinonoid ring and ν(C=N) on the quinoid ring. This phenomenon indicated the changing structure of PAni to be Emeraldine base form. KEY WORDS : Aniline, Annealing, Polyaniline, Rechargeable battery, Temperature effect Bull. Chem. Soc. Ethiop. 2019 , 33(3), 551-559. DOI: https://dx.doi.org/10.4314/bcse.v33i3.15

Polyaniline Films as Electrochemical-Proton Pump for Acidification of Thin Layer Samples.

Here, we provide the first experimental evidence of proton release from polyaniline (PANI) films subjected to anodic potentials at environmental pHs. We conducted an extensive characterization of unpolarized/polarized PANI films-synthesized by traditional sequential voltammetric scanning-by using spectroelectrochemistry, synchrotron radiation-X-ray photoelectron spectroscopy, near edge X-ray absorption fine structure, and potentiometric pH sensing in the vicinity of the PANI layer. This new insight enables the utilization of PANI as a proton pump, which is actively tuned through an electrochemical pulse, so as to controllably acidify well-confined thin layer samples. Furthermore, we demonstrate the analytical significance of this system by measuring the alkalinity of artificial and natural water samples by using two faced planar PANI electrodes, one working as a proton source and the other one as pH electrode. Finally, the impact of this approach is 2-fold: (i) all-solid-state electrode materials may be used with devisible consequences in miniaturized and implementable submersible probes, and (ii) rapid determination of alkalinity as compared to traditional approaches together with a versatility in pH adjustment in any kind of sample, among other applications.

A study on silver nanoleaf-decorated PANI electrodes for improved electrochemical performance

In this work, electrochemically synthesized polyaniline (PANI) electrode surface was modified by decorating silver nanoleaf (AgNL). AgNLs acted as a promising candidate for electrochemical sensing by providing high oxidation potential. All prepared PANI/AgNL electrodes were subjected to physicochemical characterization techniques such as the surface morphological study by field emission scanning electron microscopy; the structural and elemental detection of PANI and Ag was confirmed by Fourier transform infrared spectroscopy and energy-dispersive X-ray analysis. Electrocatalytic activity and sensing parameters of optimized PANI/AgNL electrode were explored using chronoamperometric response, cyclic voltammetry performance and corresponding calibration plots regarding the sensing mechanism. The surface-modified PANI/AgNL type III electrode showed excellent electrocatalytic properties and efficient electrode kinetics which is high regarding the electrochemical application in the present study. The improved sensitivity noticed for type III electrode is 4.3124 mA mM−1 cm−2 and limit of detection 0.06 μM. And it also displayed notable stability and reproducibility good current sensitivity.

A dual-doped strategy to enhance the electrochemical performances of electropolymerized polyaniline electrodes for flexible energy storage

We have designed a simple dual-doped strategy to boost the supercapacitive properties of polyaniline (PANi) electrodes. Specifically, dual-doped PANi (DD-PANi) electrodes are prepared via electrochemical polymerization, during which phosphoric acid and hydrochloric acid serve as dopants simultaneously. Electrochemical measurements indicate that the DD-PANi electrodes exhibit substantially improved electrochemical properties with respect to single-doped PANi electrodes (i.e., phosphoric acid-doped PANi and hydrochloric acid-doped PANi electrodes). This improvement can be attributed to the fact that dual-doped strategy changes the morphology and roughness of electropolymerized PANi films, thus leading to increased electroactive surface area and short pathway for electron/ion transport. The resultant DD-PANi electrodes exhibit high areal capacitance of 382.1 mF cm−2 at 0.5 mA cm−2, as well as ideal cycling performance (retaining 91.2% of initial capacitance after 5000 cycles). Furthermore, we have explored the feasibility of DD-PANi electrodes for high performance flexible solid-state supercapacitors. The assembled supercapacitor using DD-PANi electrodes features high mechanical flexibility, good electrochemical capacitive properties, and superior long-term stability (including deformation stability and electrochemical stability), which ensure its potential for applications in flexible energy storage devices.

Aqueous Route Synthesis of PAni Electrodes by Chemical Bath Deposition and Their Cyclic Voltammetric Analyses at Different Scan Rates

AbstractThe present work elaborates the aqueous route synthesis of polyaniline (PAni) electrodes for supercapacitors using chemical bath deposition (CBD) method and study of effective of scan rate on the cyclic voltammetric (CV) behavior. In the synthesis work, 1 m aniline and 1 m H2SO4 were taken in 2:2 ratio and kept for constant stirring and 1 m aqueous solution of (NH4)2S2O8 was added slowly in it. Stainless steel substrates were immersed in the reaction bath at room temperature for 1 h. The formation of PAni was confirmed by FT‐IR spectroscopic study. XRD analysis confirms the amorphous nature of the prepared PAni thin films. Contact angle study shows the hydrophilic behavior of the PAni electrodes. Obtained electrodes were subjected to cyclic voltammetric study at various scan rate from 5 to 100 mV s–1 in 1 m KOH electrolyte. Observed maximum specific capacitance was 516.34 F g–1 at 5 mV s–1 scan rate.

Novel composite electrode material derived from hypercross-linked polymer of pyrene and polyaniline for symmetric supercapacitor

Abstract Herein, we report the fabrication of composite electrode (PyHCP-800/PANI) by two step method. Firstly, hypercross-linked polymer of pyrene (PyHCP) synthesized by a simple Friedel-Crafts alkylation method and subsequent carbonization at 800 °C to yield porous carbon of PyHCP (PyHCP-800). Secondly, polyaniline (PANI) was electrochemically grown on the surface of PyHCP-800. The synthesized PyHCP and PyHCP-800 was characterized by physicochemical characterization techniques. The composite shows excellent electrochemical behavior than pristine PyHCP-800 and PANI electrode. In three electrode system, PyHCP-800/PANI composite exhibits specific capacitance of 62.6 F g−1 at 0.1 A g−1. Also, the fabricated symmetric supercapacitor (SSC) device (PyHCP-800/PANI || PyHCP-800/PANI) delivers outstanding cycle life with 90.67% retention for 2000 cycles.

Boosting the electrochemical performance of polyaniline based all-solid-state flexible supercapacitor using NiFe2O4 as adjuvant

Polyaniline (PANI) as supercapacitor electrode component has received increasing attention due to its high theoretical capacitance, ease of preparation and offers flexibility to fabricate device at low cost. However, PANI suffers from large volume change during doping-dedoping process, and the structural instability becomes more severe at high current and on repetitive cycling, which create challenges in replicating the theoretical capacitance in practical device form. Herein, we demonstrate the fabrication of a PANI based stable and high performance supercapacitor electrode by engineering PANI nano-architecture with NiFe2O4 (NF) nanoparticles. Notably, the optimized composite electrode showed outstanding stability over the pristine PANI electrode for a wide range of charge-discharge current density (1–10 mA/cm2). An all solid state flexible symmetric supercapacitor was fabricated using the optimized composite electrode, which showed high specific and areal capacitance of 334 F/g and 668 mF/cm2, respectively at 1 mA/cm2 current density. The device also showed excellent cyclic stability with only 1.07 ∗ 10−3% capacitance loss per cycle for tested >7000 cycles. Noteworthy, the fabricated device showed even higher capacitance when folded and under pressure applied, indicating its suitability to be used in flexible and bendable devices.

Electrochemical characterization of RuO2-Ta2O5/polyaniline composites as potential redox electrodes for supercapacitors and hydrogen evolution reaction

RuO2-Ta2O5 electrode covered with polyaniline (PANI) was prepared by sintering and electrodeposition. X-ray photoelectron spectroscopy confirmed the presence of RuO2-Ta2O5 and PANI and the strong interaction between RuO2-Ta2O5 and PANI in the RuO2-Ta2O5/PANI composite. The crystalline structure of RuO2-Ta2O5/PANI was verified by XRD. SEM analysis revealed that the RuO2-Ta2O5/PANI electrode had a nano-fibrous morphology with a crystal plane and some pores. The supercapacitive performance of RuO2-Ta2O5/PANI was evaluated by cyclic voltammetry and charge-discharge chronopotentiometry. RuO2-Ta2O5/PANI had a high specific capacitance (428 F/g), specific energy (26.7 Wh/kg at a discharge current density of 0.5 mA/cm2), and power density (2.4 kW/kg at a discharge current density of 4.0 mA/cm2). The attractive capacitive properties of RuO2-Ta2O5/PANI may be attributed to the porous morphology of RuO2-Ta2O5 covered with PANI. In addition, the as-prepared RuO2-Ta2O5 and RuO2-Ta2O5/PANI electrodes had Tafel slopes of −55.8 and −69.2 mV/dec, respectively, which make them potential H2 evolution electrocatalysts.

Redox-Active Gel Electrolyte Combined with Branched Polyaniline Nanofibers Doped with Ferrous Ions for Ultra-High-Performance Flexible Supercapacitors.

In this work, the effects of utilizing an Fe2+/Fe3+ redox-active electrolyte and Fe2+-doped polyaniline (PANI) electrode material on the performance of an assembled supercapacitor (SC) were studied. The concentration of the redox couple additive in the electrolyte of the SC was optimized to be 0.5 M. With the optimized concentration of 0.4 M Fe2+, the doped PANI branched nanofibers electropolymerized onto titanium mesh were much thinner, cleaner, and more branched than normal PANI. A specific capacitance (Cs) of 8468 F g−1 for the 0.4 M Fe2+/PANI electrode in the 1 M H2SO4 + 0.5 M Fe2+/Fe3+ gel electrolyte and an energy density of 218.1 Wh kg−1 at a power density of 1854.4 W kg−1 for the resultant SC were achieved, which were much higher than those of the conventional PANI electrode tested in a normal H2SO4 electrolyte (404 F g−1 and 24.9 Wh kg−1). These results are among the highest reported for PANI-based SCs in the literature so far and demonstrate the potential effectiveness of this strategy to improve the electrochemical performance of flexible SCs by modifying both the electrode and electrolyte.

Highly Selective and Reproducible Electrochemical Sensing of Ascorbic Acid Through a Conductive Polymer Coated Electrode.

The surface of an Au-disc electrode was modified through electro polymerization of aniline, in the presence of dodecyl benzene sulphonic acid (DBSA) and sulphuric acid (H2SO4) solution. The polymerization conditions were pre-optimized so that micelle formation and solution coagulation could be minimized and surfactant doped polyaniline film could be obtained through a quick, simple and one step polymerization route. The synthesized material was characterized via Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and cyclic voltammetry (CV). The effective surface area of the Au-disc, calculated through cyclic voltammetry, was immensely increased through a polyaniline (PANI) coating (0.04 and 0.11 cm2 for bare and PANI coated gold respectively). The modified electrode was utilized for ascorbic acid (AA) sensing. The changing pH of electrolyte and scan rate influenced the PANI electrode response towards AA. The modified electrode was highly selective towards AA oxidation and showed a very low limit of detection i.e. 0.0267 μmol·L–1. Moreover, the PANI coating greatly reduced the sensing potential for AA by a value of around 140 mV when compared to that on a bare gold electrode.

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.

Biowaste-derived carbon black applied to polyaniline-based high-performance supercapacitor microelectrodes: Sustainable materials for renewable energy applications

Biowaste, derived from cooking-oven-produced carbon nanoparticles (WCP), are incorporated into polyaniline (PANI) via in-situ chemical oxidative polymerization to achieve excellent electrochemical properties for application in supercapacitors. The WCP-PANI composite electrodes have shown high-performance charge storage, due to combinatorial effect of electrical double layer capacitance from WCP and pseudocapacitance from PANI. With increase in the WCP percolation, work function of PANI is increased, which improves the charge-trapping capabilities of composites. For such distinct charge-trapping mechanism, areal capacitance of the composite microelectrode remains near-constant with increase in scan rate or current density. This indicates the suppression of diffusion limitations at higher scan rates to considerably enhance the rate capability. Also, with increasing polymerization time, strong interaction in this conjugated system greatly improves the charge-transfer reaction between PANI and WCP. The areal capacitance of the composite electrode is found to increase more than 600 times over pure PANI electrode. Moreover, energy-power performance of the microelectrode reveals almost 550% increment in the power density with a mere 1% decrement in energy density. Such rationally synthesized WCP-PANI composite electrodes using biowaste carbon nanomaterials, provide opportunities for the development of next-generation green-supercapacitors with improved energy storage performance.