Electrochemical Deposition Of Polyaniline Research Articles

Ultra-high sensitivity pH sensor based on vertical organic electrochemical transistors with extended gate.

Anultra-high sensitivity pH sensor based on vertical organic electrochemical transistors (vOECT) with extended gate was proposed. The vOECT, which exhibited high transconductance (gm), was forthe first time used in the preparation of apH sensor. The extended gate was modified by electrochemical deposition of polyaniline (PANI) using the cyclic voltammetry (CV) technique. Open circuit potential (OCP) measurements were used to optimize the scan rate, showing a super-Nernstian sensitivity at all scan rates. The pH sensor based on vOECT with extended gate was investigated at different pH levels, and it exhibited an ultra-high sensitivity of 3363.6 µA/pH in the pH range 5-9, which was about 36 times greater than the maximum current sensitivity (91 µA/pH) of other transistor-based pH sensors, to the best of our knowledge. This pH sensor performed excellently in terms of reversibility, long-term stability, and selectivity. To confirm the reliability of the pH sensor, we conducted measurements on real samples using this pH sensor and compared the results with those obtained from a standard pH meter. The ultra-high sensitivity pH sensor based on vOECT with extended gate offers a sensitive and promising alternative in environmental monitoring, food safety, chemistry, clinical diagnostics, and bio-sensing applications.

Electrodeposition of polyaniline on high electroactive indium tin oxide nanoparticles-modified fluorine doped tin oxide electrode for fabrication of high-performance hybrid supercapacitor

In this study, hierarchical polyaniline (PANI) nanosheets were electrochemically deposited on indium tin oxide nanoparticles coated fluorine-doped tin oxide glass (ITONPs-FTO) substrate from an aqueous solution containing 0.5 M aniline and 1 M H2SO4. The ITONPs provide efficient support with high electroactive surface area in the electrochemical deposition of PANI and produce excellent PANI films. The developed PANI film deposited on the ITONPs-FTO electrode was characterized via field-emission scanning-electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. A hybrid supercapacitor (HSC) was fabricated using the developed PANI deposited ITONPs-FTO as a positrode and the jute sticks derived activated carbon nanosheets coated FTO (JAC-FTO) as a negatrode. Because of its high capacitive performance, unique structures of electrode materials, and optimum operating potential window, the fabricated PANI-ITONPs-FTO//JAC-FTO HSC performed excellently in 0.1 M HCl aqueous electrolyte, delivering a high areal capacitance of 318 mF/cm2 at a 1.0 mA/cm2 current density and exhibit a high energy density of 28 µWh/cm2 at a high power density of 400 µW/cm2. Moreover, the HSC exhibits excellent cyclic stability with ∼ 87% Coulombic efficiency and ∼ 91% capacitance retention after 1000 charge–discharge cycles.

Electrochemical deposition of polyaniline on the stainless steel mesh for the extraction of polycyclic aromatic hydrocarbons

In this study, the polyaniline (PANI) coating was synthesized via electrochemical deposition on the stainless steel mesh and loaded in the form of the disk in a column as solid-phase extraction cartridge. The prepared cartridge was applied for the extraction of polycyclic aromatic hydrocarbons (PAHs) from real water samples and determination with gas chromatography-flame ionization detector (GC − FID). The PANI-coated stainless steel mesh possessed a rough surface and porous structure and showed excellent stability. The SPE-GC-FID method based on PANI coated stainless steel mesh showed wide linear range (0.01–100 ng mL−1), low limits of detection (0.003–0.01 ng mL−1), and good repeatability (4.5–6.1%). The method was applied for the extraction of PAHs in the real water samples (i.e. tap water, well water, river water, and wastewater) with satisfactory relative recovery in the range of 95.8–99.7%.

Wearable supercapacitor based on polyaniline supported by graphene coated polyester textile

Wearable supercapacitors have broad application prospects in emerging portable devices. To realize the large-scale application, it is necessary to develop a low-cost and large-scale method to fabricate wearable electrode with high electrochemical performance. Here, polyaniline supported by graphene coated polyester textile (PANI/GPT) electrode is prepared through a simple and low-cost method. First, graphene ink with high concentration is prepared, and then the polyester textile is coated by graphene through a repeatedly soaking-drying process. Subsequently, PANI/GPT electrode is prepared by electrochemical deposition of polyaniline (PANI) on graphene coated polyester textile. The ratio of PANI in the textile electrode has been systematically modified and the obtained textile electrode possesses good energy storage performance with specific capacitance reaching 896.50 F g−1 and good rate capability. The assembled flexible supercapacitor also owns excellent flexibility with capacitance retention of 95.10% after bending for up to 5000 cycles. Such high-performance textile electrodes and the low-cost method can be widely applied to develop other wearable energy storage devices.

Electrochemical Deposition of Polyaniline on the Stainless Steel Mesh for the Extraction of Polycyclic Aromatic Hydrocarbons

In this study, the polyaniline (PANI) coating was synthesized via electrochemical deposition on the stainless steel mesh and loaded in the form of the disk in a column as solid-phase extraction cartridge. The prepared cartridge was applied for the extraction of polycyclic aromatic hydrocarbons (PAHs) from real water samples and determination with gas chromatography-flame ionization detector (GC−FID). The PANI-coated stainless steel mesh possessed a rough surface and porous structure and showed excellent stability. The SPE-GC-FID method based on PANI coated stainless steel mesh showed wide linear range (0.01−100 ng mL−1), low limits of detection (0.003−0.01 ng mL−1), and good repeatability (4.5−6.1%). The method was applied for the extraction of PAHs in the real water samples (i.e. tap water, well water, river water, and wastewater) with satisfactory relative recovery in the range of 95.8−99.7%.

Non-woven fabric electrodes based on graphene-based fibers for areal-energy-dense flexible solid-state supercapacitors

Abstract Nowadays, lightweight, flexible, and wearable sustainable electric-power sources have attracted increasing attention due to the rapid development of portable electronics. Graphene fiber fabrics, as newly discovered carbon textiles, have exhibited attractive properties for wearable power devices. How to realize scalable construction of non-woven graphene-based fabric electrodes with high areal capacitance is challenging for portable electronics. Here, a novel coagulation bath fabrication technique was firstly reported to prepare reduced graphene oxide fiber fabrics (rGOFFs) for areal-energy-dense supercapacitors. The as-prepared rGOFFs showed high flexibility and conductivity. The symmetric supercapacitors (SCs) assembled with rGOFFs (95 μm) based fabric electrodes performed a high specific gravimetric capacitance (Cm) of 285 F/g at 0.1 A/g and 220 F/g at 1 A/g. The areal capacitance (Ca) of rGOFFs (220 μm) based electrode reached up to 2812 mF/cm2 at 1 mA/cm2. After electrochemical deposition of polyaniline (PANI) on rGOFFs (220 μm) substrate, the Ca of rGOFF@PANI – 220 μm based electrode was intensified to 3828 mF/cm2 at 1 mA/cm2 (172 F/cm3). The symmetric all-solid-state SCs showed an energy density from 28 μWh/cm2 (254 μW/cm2) to 11 μWh/cm2 (4950 μW/cm2). Overall, the as-designed rGOFFs based fabric electrodes and their fabrication techniques are of great potential for the next-generation multi-functional textile electronics.

Preparation oaf polyaniline/diazonium salt/TiO2 nanotube arrays as supercapacitor electrode by electrochemical grafting and deposition

Polyaniline/diazonium salt/TiO2 nanotube arrays (PANI/DZ/TiO2 NAs), as a supercapacitor electrode material, are fabricated by two-step anodic oxidation of titanium foils, electrochemical grafting and reduction of diazonium salts, and electrochemical deposition of polyaniline. Surface morphology, crystallization, and chemical compositions of nanocomposites are characterized by SEM, EDX, XRD, and Raman. Electrochemical tests indicate that PANI/DZ/TiO2 NAs have excellent capacitance of 1108.5 F g−1 when the current density is 0.6 A g−1. With the current density increasing 20 times to 12 A g−1, the capacitance remains about 77.5%, demonstrating its good rate performance. Moreover, after 2000 charge–discharge cycles at 12 A g−1, the capacitance retains 83.7% of the initial value, showing its good cycling stability.

Ion and solvent transfer of polyaniline films electrodeposited from deep eutectic solvents via EQCM

We report herein the electrochemical polymerisation of aniline from a choline chloride (ChCl)-based deep eutectic solvent (DES) at room temperature in both the presence and absence of deionised water in the solvent. The current study used Propeline as the DES electrolyte, which we found to be rich in protons (i.e. similar to protic ionic liquids) and which allowed the polymerisation of aniline in this system. The morphology of films was characterised by scanning electron microscopy (SEM) and atomic force microscopy (AFM), which showed the polymer film to have a compact structure and rough surface. The electrochemical quartz crystal microbalance (EQCM) was used for the first time to investigate the mass changes that occur during the electrochemical deposition of polyaniline (PANI) in situ, and was used to monitor cation, anion, and solvent transport when PANI films were immersed in pure Propeline and 0.5 M H2SO4 solution (monomer free) at 25 °C and 50 °C. In the case of the PANI exposed to pure Propeline at room temperature, the mass change increased continuously in both oxidation and reduction switching due to anion transfer dominating the mass change, while the PANI exposed to pure Propeline at 50 °C was found to form due to a two-step combined mechanism, showing excellent redox switching stability with changing mass. These variations in mass tend to be dominated by cation expulsion in the first oxidative process (the later reductive process being cation insertion) and by anion insertion in the second oxidative stage (the early reductive process being anion expulsion). In aqueous systems, the mechanism of mass change was dominated by anion movement associated with solvent transfer. The movement of neutral species in Propeline and water is in the reverse direction to those of cation or anion transfer.

Electrochemical Deposition of Polyaniline on Carbon Steel for Corrosion Study in Geothermal Solution

Polyaniline has been widely developed for many applications, e.g. sensor, supercapacitor components, electrochromic devices, and anticorrosion pigments. Although the addition of polyaniline pigment in organic coatings has been an alternative for corrosion protection in industrial applications, the protection mechanism is still not fully understood. Herein in this study, as a part of the development of polyaniline/silicon dioxide coating for geothermal application, polyaniline has been deposited electrochemically on carbon steel surface in oxalic acid medium and tested in geothermal solution to understand the contribution of polyaniline to the corrosion protection of a polyaniline-based composite in the geothermal system. To observe the surface/interface reaction between the electrolyte and electrode surface during the electrochemical polymerization, electrochemical impedance spectroscopy (EIS) was applied after each cycle. For corrosion study in the geothermal application, an artificial geothermal solution was used with the composition of 1,500 mg/l Cl-, 20 mg/l SO42-, 15 mg/l HCO3-, 200 mg/l Ca2+, 250 mg/l K+, and 600 mg/l Na+, and pH 4 to simulate a geothermal brine found in Sibayak, Indonesia. An electrochemical measurement was performed by monitoring the open circuit potential over seven days, with the interruption by EIS every 22 hours. The experiments were performed at room temperature and 150 °C (1 MPa) in an oxygen-free environment. Impedance spectra showed a reduction of the total impedance value of approximately 10 times for specimens measured at 150 °C compared to the specimens measured at room temperature, suggesting a less stable layer at high temperature.

A Novel Porous Carbon-Based Non-Metal Catalyst Based on Electrochemical Deposition of Polyaniline: Synthesis, Characterization and Electrochemical Performance

Polyaniline-based porous carbon material with high surface area (769.86~1341.12 m2/g) was prepared via electrochemical method combined with high temperature carbonization process. A very clear pore structure can be observed by scanning electron microscope. The ORR activity and the electrochemical stabilities of the porous carbons were compared to the commercial Pt/C by linear potential scan (LSV) and chronoamperometry, respectively. The catalytic activity for oxygen reduction reaction of the porous carbon increases by increasing carbonization temperature. The oxygen reduction reaction for the prepared porous carbon which was carbonized at 850℃ is catalyzed by a four-electron transfer pathway. Furthermore, the current density of oxygen reduction reaction of the synthetic porous carbon decreases by 33%@10 h, which is lower than commercial Pt/C (64%@10 h).

Omnidirectionally Stretchable High-Performance Supercapacitor Based on Isotropic Buckled Carbon Nanotube Films.

The emergence of stretchable electronic devices has attracted intensive attention. However, most of the existing stretchable electronic devices can generally be stretched only in one specific direction and show limited specific capacitance and energy density. Here, we report a stretchable isotropic buckled carbon nanotube (CNT) film, which is used as electrodes for supercapacitors with low sheet resistance, high omnidirectional stretchability, and electro-mechanical stability under repeated stretching. After acid treatment of the CNT film followed by electrochemical deposition of polyaniline (PANI), the resulting isotropic buckled acid treated CNT@PANI electrode exhibits high specific capacitance of 1147.12 mF cm(-2) at 10 mV s(-1). The supercapacitor possesses high energy density from 31.56 to 50.98 μWh cm(-2) and corresponding power density changing from 2.294 to 28.404 mW cm(-2) at the scan rate from 10 to 200 mV s(-1). Also, the supercapacitor can sustain an omnidirectional strain of 200%, which is twice the maximum strain of biaxially stretchable supercapacitors based on CNT assemblies reported in the literature. Moreover, the capacitive performance is even enhanced to 1160.43-1230.61 mF cm(-2) during uniaxial, biaxial, and omnidirectional elongations.

Supercapacitive properties of polyaniline/hydrous RuO2 composite electrode

A composite electrode based on polyaniline (PANI) and hydrous RuO2 is prepared by electrochemical deposition of PANI onto hydrous RuO2 (PANI/RuO2) and its supercapacitive properties are investigated using cyclic voltammetry. The specific capacitances of PANI/RuO2 and hydrous RuO2 electrodes are determined to be 708 and 517 F g−1 at 5 mV s−1, respectively. Simple electrodeposition of PANI on the hydrous RuO2 can achieve comparatively greater capacitance values.

Pt-polyaniline nanocomposite on boron-doped diamond electrode for amperometic biosensor with low detection limit

Boron-doped diamond electrodes covered with a nanostructured Pt nanoparticle-polyaniline composite have been fabricated and employed as sensitive amperometric sensors with low detection limit. A highly conductive boron-doped diamond thin film (BDD) was prepared by chemical vapor deposition, and its morphology was characterized by scanning electron microscopy and transmission electron microscopy. The nanostructured composite layer was grown on the BDD electrode by electrochemical deposition of polyaniline and Pt nanoparticles. Glucose oxidase (GOx) was then adsorptively immobilized on the modified BDD electrode. The biosensor displays a large surface area, high catalytic activity of the Pt nanoparticles, efficient electron mediation through the conducting polymer, and low background current of the electrode. The biosensor exhibits an excellent response to glucose, with a broad linear range from 5.9 μM to 0.51 mM, a sensitivity of 5.5 μA·mM−1, a correlation coefficient (R) of 0.9947, and a detection limit of 0.10 μM. The apparent Michaelis-Menten constant (KMapp) and the maximum current density of the electrode are 4.1 mM and 0.021 mA, respectively. This suggests that the immobilized GOx possesses a higher affinity for glucose at the lower KMapp, and that the enzymatic reaction rate constitutes the rate-limiting step of the response.

Electrochemical synthesis of polyaniline from aniline/cyclodextrin solutions

The influence of cyclodextrin on the electrochemical deposition of polyaniline from neutral perchloric solutions was determined. The oxidation of aniline and the polymer growth were investigated by cyclic voltammetry and electrochemical quartz crystal micro-balance in the presence of either β-cyclodextrin or sulfated β-cyclodextrin. The obtained results show the significant impact of the cyclodextrins on polyaniline growth rate, morphology and electrochemical properties of the resulting layers. The different effect was obtained in the presence of β-cyclodextrin compared to sulfated β-cyclodextrin. The incorporation of β-cyclodextrin in the polyaniline layer results in “comb like formations” within the layer while the incorporation of sulfated β-cyclodextrin in the polyaniline layer leads to more irregular morphologies and to the layers with the increased ohmic resistance.

Effect of temperature on the electrochemical synthesis and properties of polyaniline films

Abstract The effect of temperature on the electrochemical oxidative polymerization of aniline and on the electrochemical properties of the resulting polyaniline (PANI) film was studied. The electrochemical deposition of PANI has been carried out on platinum at different temperatures. Three different films (PANI-25, PANI-40 and PANI-60) have been prepared at 25, 40 and 60 °C by electrochemical polymerization and characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Increasing the synthesis temperature leads to an increase of the polyaniline films thickness from 0.4 to 0.9 μm and, respectively, 1.1 μm, associated with an increase of the films capacitances from 3 × 10−2 F cm−2 to 7 × 10−2 F cm−2 and 10 × 10−2 F cm−2. The impedance measurements showed that only PANI-25 and PANI-40 exist in the conductive state over a large potential window, while PANI-60 has an intermediate behavior at low and high electrode potentials.

Influence of the scan rate on the morphology of polyaniline grown on conducting fabrics. Centipede-like morphology

We report the apparition of different polyaniline (PANI) morphologies when different scan rates were employed in the electrochemical deposition of PANI on conducting fabrics. The most impressive structure obtained was the centipede-like morphology. PANI was deposited on conducting textiles of polyester covered with polypyrrole (PPy)/anthraquinone sulphonic acid (AQSA) by means of cyclic voltammetry. With the scan rates of 50 mV s −1 and 5 mV s −1 PANI with centipede-like morphology was obtained in the first scans. Globular PANI gained importance for higher number of scans due to the formation of new nucleation sites. When a scan rate of 1 mV s −1 was employed a variety of different morphologies were observed, such as: fibrillar, stalagmite-like, coral-like and plain irregular forms. Such variety of morphologies is due to the slow growth that allowed different types of morphologies.

Chemical and electrochemical deposition of conducting polyaniline on lead

Chemical and electrochemical deposition of polyaniline (PANi) on lead from aqueous electrolytes has been carried out. PbO 2 is used for chemical deposition. Pb is anodizing in a favorite condition, potentiostatically, until PbO 2 is produced. The produced PbO 2 has been used as oxidant, which oxidized aniline and deposited chemically produced PANi films on lead. The chemically produced PANi acts as a passive layer and protects the substrate from dissolution during anodic polarization. Its quality is as high as electrochemically synthesized one. The chemically deposited PANi can be used for the electrodeposition of PANi films by convenient methods. In this procedure, 1M H 2SO 4 should be used as supporting electrolyte to achieve suitable results. Since, PbO 2 as oxidant has the highest reduction capacity in this concentration, the produced PANi has the best quality and also SO 4 2− is the best counter ion for the synthesis of PANi. Lead oxidation does not occur during electrochemical deposition of PANi. This is a modified electrode on an inexpensive metal which can resists corrosion by a coated PANi film. The films show good electroactivity in acidic electrolytes similar to that of the PANi deposited on platinum, which indicates that the underlying oxidizable metal is fully protected. Among the electrochemical methods, galvanostatic deposition has given the best results. Very adherent thickness-controlled PANi films were obtained by this method.

Film mechanical resonance phenomenon during electrochemical deposition of polyaniline

Crystal admittance measurements during potentiodynamic electrodeposition from aqueous HCl of polyaniline films on a thickness shear mode resonator show the phenomenon of film resonance. This special situation arises when the combination of materials properties (film shear modulus and density) and sample nature (film thickness) is such that the acoustic phase shift across the film, φ = π/2 radians. Admittance spectra in the acoustically thick (but pre-film resonance) region were fitted to a standard Butterworth van Dyke (BvD) electrical equivalent circuit (with series L, C, and R elements) to yield film storage and loss shear moduli. From these values, it was possible to calculate φ of the growing film and thereby track the onset of film resonance. As φ approached π/2 radians, the admittance peak rapidly shifted to higher frequencies and changed dramatically in amplitude. An electrical equivalent circuit with parallel L, C, and R elements was used to model film resonance data; this simplified model ignores the contribution of the bathing electrolyte. Agreement of film shear moduli from both models, and of resonant film thickness from the parallel element equivalent circuit model and coulometric extrapolation of pre-resonant responses, supports the basic tenets of the film resonance model. At film resonance, the cyclic voltammetric response changed dramatically; it is speculated that this is a consequence of the unusual polymer dynamics at film resonance.

High capacitance properties of polyaniline by electrochemical deposition on a porous carbon substrate

Electrochemical deposition of polyaniline (PANI) is carried out on a porous carbon substrate for supercapacitor studies. The effect of substrate is studied by comparing the results obtained using platinum, stainless steel and porous carbon substrates. PANI deposited at 100 mV s −1 sweep rate by potentiodynamic technique on porous carbon substrate is found to possess superior capacitance properties. Experimental variables, namely, concentrations of aniline monomer and H 2SO 4 supporting electrolyte are varied and arrived at the optimum concentrations to obtain a maximum capacitance of PANI. Low concentrations of both aniline and H 2SO 4, which produce PANI at low rates, are desirable. The PANI deposits prepared under these conditions possess network morphology of nanofibrils. Capacitance values as high as 1600 F g −1 are obtained and PANI coated carbon electrodes facilitate charge–discharge current densities as high as 45 mA cm −2 (19.8 A g −1). Electrodes are found to be fairly stable over a long cycle-life, although there is some capacitance loss during the initial stages of cycling.

The electrochemical deposition of polyaniline at pure aluminium: electrochemical activity and corrosion protection properties

Polyaniline films were electrodeposited at pure aluminium from a tosylic acid solution containing aniline. These polymer films exhibited similar characteristics as pure polyaniline electrosynthesized at an inert platinum electrode, when removed from their respective substrates and dissolved in NMP. Both polymers had similar molecular weights and similar UV-visible absorption spectra. However, the aluminium substrate had a considerable effect on the electrochemical activity of the films. The polyaniline films deposited at aluminium appeared to lose electroactivity and the electrochemical impedance data were governed by the oxidized aluminium substrate. This is consistent with a galvanic interaction between the polymer and the aluminium substrate, giving rise to oxidation of the aluminium and reduction of the polymer. The polyaniline deposits appeared to offer only a slight increase in the corrosion resistance of aluminium. Surface potential measurements, using a scanning vibrating probe, showed that attack initiated underneath the polymer under anodic polarization conditions, indicating that chloride anions diffuse across the polymer to react at the underlying aluminium substrate.