Polyaniline Thin Films Research Articles

1 ppm-detectable hydrogen gas sensor based on nanostructured polyaniline

The hydrogen (H2) energy industry has continued to expand in recent years due to the decarbonization of the global energy system and the drive towards sustainable development. Due to hydrogen’s high flammability and significant safety risks, the efficient detection of hydrogen has become an increasingly hot issue today. In this work, a new type of relatively fast and responsive conducting polymer sensor has been demonstrated for tracing H2 gas in a nitrogen environment. Inspiration of unique properties of carbon nanotube (CNT) and graphene, polyaniline (PANI) hollow nanotubes, PANI thin films are fabricated to study for structural-properties investigation. The PANI hollow nanotube sensor ensures the 1 ppm hydrogen gas detection at room temperature, and exhibits high sensitivity (29%) and fast response and recovery times of 15 and 17 s, follows by PANI thin film sensor (20%), response and recovery times of 65s and 45s. This conducting polymer-based hydrogen sensor holds promise for the early detection of H2 leaks in a wide range of industries.

Optimized Drop-Casted Polyaniline Thin Films for High-Sensitivity Electrochemical and Optical pH Sensors

Conducting polymers used in chemical sensors are attractive because of their ability to confer reversible properties controlled by the doping/de-doping process. Polyaniline (PANI) is one of the most prominent materials used due to its ease of synthesis, tailored properties, and higher stability. Here, PANI thin films deposited by the drop-casting method on fluorine-doped tin oxide (FTO) substrates were used in electrochemical and optical sensors for pH measurement. The response of the devices was correlated with the deposition parameters; namely, the volume of deposition solution dropped on the substrate and the concentration of the solution, which was determined by the weight ratio of polymer to solvent. The characterisation of the samples aimed to determine the structure–property relationship of the films and showed that the chemical properties, oxidation states, and protonation level are similar for all samples, as concluded from the cyclic voltammetry and UV–VIS spectroscopic analysis. The sensing performance of the PANI film is correlated with its relative physical properties, thickness, and surface roughness. The highest electrochemical sensitivity obtained was 127.3 ± 6.2 mV/pH, twice the Nernst limit—the highest pH sensitivity reported to our knowledge—from the thicker and rougher sample. The highest optical sensitivity, 0.45 ± 0.05 1/pH, was obtained from a less rough sample, which is desirable as it reduces light scattering and sample oxidation. The results presented demonstrate the importance of understanding the structure–property relationship of materials for optimised sensors and their potential applications where high-sensitivity pH measurement is required.

Electrocoating of polyaniline on graphite carbon and activated carbon cloth surfaces as an anode and its effect on performance of microbial fuel cell

AbstractMicrobial fuel cell (MFC) is a bioelectrochemical‐based reactor that can generate electrical energy directly from wastewater by utilizing microbial activity that oxidizes the waste organic matter. This study aims to synthesize polyaniline (PANI) and deposit on a graphite carbon electrode (GCE) and activated carbon cloth (ACC) surface to use as an anode material for MFCs. The MFC performance was evaluated using oxygen and ferricyanide as electron acceptors. PANI was electropolymerized from its aniline monomer and deposited using an electrophoretic deposition method onto the electrode surface. A PANI thin film was characterized using FTIR, field emission scanning electron microscopy (FESEM), BET, and electrochemical analysis. The analysis results show the characteristic peaks of PANI at 1557 cm−1, demonstratinjg the existence of quinoid rings (NQN), while the peaks at 1479 and 1400 cm−1 corresponding to the benzenoid (NBN) stretching in the PANI structure. The FESEM analysis confirmed that PANI appeared to have a porous structure on modified electrodes. It was found that the best system was MFC with ferricyanide as the electron acceptor. The highest power density produced is 254 mWm−2 from GCE‐PANI and 16.47 mWm−2 from ACC‐PANI. The normalized energy recovery of GCE‐PANI and ACC‐PANI in ferricyanide is 0.115 kWh kgCOD−1 and 5.67 × 10−3 kWh kgCOD−1, respectively. The COD removal was observed to be 88.8% for GCE‐PANI and 87.2% for ACC‐PANI from 1000 mg/L COD.

Methanol electrooxidation performance of nickel-modified polyaniline thin films for direct methanol fuel cells

A metal–organic composite thin film composed of polyaniline (PANI) and Ni was prepared and characterized for methanol electrooxidation reaction. First, PANI thin films were electrodeposited on a fluorine-doped tin oxide (FTO) coated glass support in an aqueous acidic solution. Subsequently, the polymer film was modified with Ni particles (FTO/PANI-Ni) by chronoamperometric (CA) technique. The composite film was characterized by structural, morphological and electrocatalytic analyses. X-ray diffraction (XRD) results confirmed the crystallization of Ni according to the cubic structure. Scanning electron microscopy (SEM) images showed that the Ni nanoparticles were uniformly dispersed on the PANI surface. The electrocatalytic performance of the FTO/PANI-Ni composite electrode for the methanol electrooxidation reaction was investigated in 0.5 M KOH solution containing methanol using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) techniques. The effects of temperature and methanol concentration on the methanol electrooxidation performance were also studied. The modified composite catalyst exhibited an electrochemically active surface area of 0.5235 cm2. The presence of Ni nanoparticles on the polymer surface promoted the adsorption of methanol molecules and facilitated the oxidation process, leading to higher current densities and better overall performance. The maximum current density was 14 mA cm-2 and the electrode maintain 68 % of its initial activity even after 200 cycles, indicating that the FTO/PANI-Ni electrode exhibited good stability. The high methanol oxidation performance of the composite electrode was associated with large real surface area, a possible synergistic effect between the polymer moleucles and Ni particles as well as high intrinsic activity of Ni for this process.

Tailoring physical properties and electrochemical performance of polyaniline thin films via chemical bath deposition

This study focuses on the properties of polyaniline (PANI) thin deposited onto glass substrates using a chemical bath method. The films were prepared under the same conditions, except for the type of oxidant used. Three oxidants were utilized: potassium per-sulfate (KPS), sodium per-iodate (NAIO4), and ferric chloride di-hydrated (FeCl3·2H2O). X-ray diffraction (XRD) analysis confirmed that all deposited films had an amorphous structure. Fourier-transform infrared spectroscopy (FT-IR) confirmed the presence of PANI films, as indicated by the recorded peaks. Scanning electron microscopy (SEM) was employed to study the surface structure and morphologies of the films, revealing nano-structured grains with varying average grain sizes depending on the oxidant type. The elemental composition of the films was analyzed using X-ray photoelectron spectroscopy (XPS). The optical band gap values were determined to be 4.06 eV, 3.93 eV, and 3.96 eV for FeCl3·2H2O, NAIO4, and KPS oxidants, respectively. The refractive index and extinction coefficient were also calculated from optical data, showing significant variations with changes in the oxidant type. The high frequency dielectric constant of the films was estimated using the Spitzer-Fan model, resulting in values of 5.15, 3.24, and 474 for FeCl3, NAIO4, and KPS oxidants, respectively. Additionally, cyclic voltammetry studies revealed that PANI/glass films grown using NAIO4 exhibited the highest specific capacity. Further investigation of PANI/FTO/glass films showed a specific capacity estimated to be 100 Fg-1 for this particular film configuration.

Correction: Incorporation of nickel particles into a polyaniline thin film for non-enzymatic glucose sensing in alkaline medium

Correction: Incorporation of nickel particles into a polyaniline thin film for non-enzymatic glucose sensing in alkaline medium

Augmentation of room temperature gas sensing properties of PANI thin films by 100 keV Ar+ ion irradiation

Polyaniline thin films were subjected to irradiation with Ar+ ions at four different concentrations: 1 × 1014, 1 × 1015, 1 × 1016, and 3 × 1016 ions/cm2, with an energy of 100 keV to improve the sensing ability. Field emission scanning electron microscope (FESEM) images revealed that the porosity as well as surface area of thin films increase significantly with the increase in fluence dose. The bandgap energy of the irradiated thin films found to decrease from 3.04 to 2.36 eV, whereas, the number of carbon atoms per cluster are found to increase from 127 to 211 atoms with increasing the Ar+ ions dose from 1x1014 to 3x1016 ions/cm2. The ratios of the areas under the curves AQ/AB are increased from 0.221 to 0.456 as the Ar+ ion fluence dose rate rose from 0 to 3 × 1016 ions/cm2. Thus, it can be assumed that the electrical conductivity of the PANI films increase with the Ar+ ion fluence dose rate via carbonaceous clustering, and the scission of polymer chains. The as-deposited PANI thin film demonstrated the lowest sensing response at approximately 33 %, while the thin film irradiated with the highest dose of 3 × 1016 ions/cm2 exhibited the highest sensing response at around 1119 % for methanol vapors at a concentration of 100 ppm.

Highly efficient polyaniline based flexible electrochemical sensor for bisphenol a detection

We report herein a novel label-free polyaniline (PANI) based bisphenol A (BPA) electrochemical sensor fabricated on a flexible polyethylene terephthalate (PET) substrate. The PANI layer was electrochemically deposited on a gold-coated PET substrate using the facile amperometric (current–time transient) technique. A thorough investigation of the PANI sensing layer was done using Raman spectroscopy and field emission scanning electron microscopy (FESEM) characterization techniques. The sensing properties of the implanted matrix for BPA detection were investigated through cyclic voltammetry (CV). The fabricated electrochemical sensor showed linearity in the concentration range of 0.05–––5.0 µM, a higher sensitivity of ∼ 56.69 A/M and a lower limit of detection (LOD) of ∼ 1.06 nM. The sensor exhibited excellent flexibility and a better shelf life of 20 weeks. The results highlight the importance of PANI thin film as an attractive matrix for the realization of electrochemical sensor for BPA detection.

Electrochromic Polymers: From Electrodeposition to Hybrid Solid Devices

This paper reports on the linear colorimetric and electrochromic (EC) characteristics of electrodeposited polyaniline (PANI) films. This paper also investigates the infrared EC properties of acid-doped PANI films. The electrochemical polymerization method was employed to create a porous and thin PANI film layer onto PET-ITO substrates. This layer was capped with WO3 film to create a gel electrolyte sandwich structure that demonstrates the compatibility of PANI films with cathodic WO3 films in full devices. The electrodeposition of the film was fabricated by applying different voltages and time, with the optimal film quality achieved with the 1.7 V voltage and a 20 min deposition period. The surface morphology, optical performance, electrochemical behavior, and molecular structure evolution are comprehensively studied in this work. The linear colorimetric behaviors and the corresponding significant changes in the structure in Raman spectra build direct strong quantitative relations in EC polymers. The well-defined oxidation and reduction peaks observed in the cyclic voltammetry indicate the ion-diffusion dominant process in the electrochromism of PANI. Significant transitions between the benzene and quinone phases in the Raman spectra are found in the bleached and colored states of polymers. This study enhances the understanding of PANI film structure and electrochemical and associated optical properties, providing more insights into the dual-function EC charge storage polymers and other energy-related functional materials.

Impact of Sulfuric Acid Concentration Variation in the Synthesis of Polyaniline and on Electrochemical Performance of Polyaniline Thin Films Prepared at Room Temperature

Impact of Sulfuric Acid Concentration Variation in the Synthesis of Polyaniline and on Electrochemical Performance of Polyaniline Thin Films Prepared at Room Temperature

Structural, electrical, optical and gas sensing properties of MgTiO3-B doped polyaniline thin films

Structural, electrical, optical and gas sensing properties of MgTiO3-B doped polyaniline thin films

Low-Cost Optical pH Sensor with a Polyaniline (PANI)-Sensitive Layer Based on Commercial Off-the-Shelf (COTS) Components.

In this paper, we presented a novel, compact, conceptually simple, and fully functional low-cost prototype of a pH sensor with a PANI thin film as a sensing layer. The PANI deposition process is truly low-cost; it performs from the liquid phase, does not required any specialized equipment, and comprises few processing steps. The resulting PANI layer has excellent stability, resistance to solvents, and bio- and chemical compatibility. The pH sensor's sensing part includes only a few components such as a red-light-emitting diode (LED) as a light source, and a corresponding photodiode (PD) as a detector. Unlike other PANI-based sensors, it requires no sophisticated and expensive techniques and components such lasers to excite the PANI or spectrometry to identify the PANI color change induced by pH variation. The pH sensor is sensitive in the broad pH range of 3 to 9, which is useful for numerous practical applications. The sensor requires a tiny volume of the test specimen, as little as 55 µL. We developed a fully integrated packaging solution for the pH sensor that comprises a limited number of components. The pH sensor comprises exclusively commercial off-the-shelf (COTS) components and standard printed circuit boards. The pH sensor is assembled using standard surface mounting technology (SMT).

Performance of Polyaniline Thin Film as a Functional Material of Acid Vapor Sensors

Polyaniline (PANI) is a conductive polymer that can be produced by the electrodeposition process. The purpose of this research is to evaluate the performance of PANI sensors on hydrochloric acid (HCl) and acetic acid (CH3COOH) vapor using a scan rate of 100 mV/s and ten cycles, a thin PANI layer was created on the surface of the ITO substrate. The PANI spectroscopic test results before and after CH3COOH vapor exposure revealed no differences and remained within the PANI functional group range. A four-point probe (FPP) test was performed to evaluate the sensing performance of the PANI thin film against analyte gas. The results of recovery time, response time, and sensitivity tended to increase as analyte concentration increased. The quickest CH3COOH sensing (1 ppm) has a reaction time of 29.7 seconds, a recovery time of 21.9 seconds, and a sensitivity of 5.11%. The greatest CH3COOH sensing (10 ppm) resulted in a reaction time of 50.3 seconds, a recovery time of 39.7 seconds, and a sensitivity of 13.64%. The reaction time for the lowest HCl sensing (1 ppm) was 42.6 s, the recovery time was 32.4 s, and the sensitivity was 7.82%. The greatest level of CH3COOH sensing (10 ppm) resulted in a response time of 60.6 s, a recovery time of 55.3 s, and a sensitivity of 16.31%. As a result, the PANI thin film is a functional material for acid gas sensors.

Incorporation of nickel particles into a polyaniline thin film for non-enzymatic glucose sensing in alkaline medium

Incorporation of nickel particles into a polyaniline thin film for non-enzymatic glucose sensing in alkaline medium

Red-Ox front propagation in polyaniline-polymer electrolyte system as a basis for spiking and rate-based neural networks and multibit ReRAM

We observed and studied the phenomenon of the redox front propagation in different polyaniline (PAni) deposited samples interfaced with liquid or solid polymeric electrolyte. The front of electrochemical conversion, in which the insulator and the conductor parts of PAni are interfaced, is studied observing the temporal evolution of the conductivity of PAni samples. The propagation of redox front was studied in electrochemically obtained thick (2 µm) and in thin (50 nm) polyaniline films, obtained using Langmuir-Blodgett (LB) method. In the configuration that we tested, the speed of the red-ox front propagation for the thin LB films was found to be 200 µm/sec opening the way for the manufacturing large neural networks, realized using PAni based memristive devices, in which the memristance can be quickly changed in the programmable manner. The prototypes of the spiking neuron connections were manufactured on the basis of lithographically developed gold contacts, bridged by electrochemically grown polyaniline and placed under polymer electrolyte layer with only one counter electrode (gate) for the whole manifold of pseudo-two-terminal memristor bridges. The spike propagation was studied in such gold-polyaniline systems. The research opens the possibility of miniature spike or rate-based neural network circuits manufacture, based on metal pads and polyaniline.

Understanding the Effect of Deposition Technique on the Structure-Property Relationship of Polyaniline Thin Films Applied in Potentiometric pH Sensor.

The comprehension of potentiometric pH sensors with polymeric thin films for new and advanced applications is a constant technological need. The present study aimed to explore the relationship between the sensitivity and correlation coefficient of potentiometric pH sensors and the structure-property relationship of polyaniline thin films. The effect of the deposition method on the sample's properties was evaluated. Galvanostatically electrodeposited and spin-coated polyaniline thin films were used as the sensing stage. Samples were electrodeposited with a current density of 0.5 mA/cm2 for 300, 600, and 1200 s and were spin coated for 60 s with an angular velocity of 500, 1000, and 2000 rpm. The electrodeposited set of films presented higher average sensitivity, 73.4 ± 1.3 mV/pH, compared to the spin-coated set, 59.2 ± 2.5 mV/pH. The electrodeposited films presented higher sensitivity due to their morphology, characterized by a larger roughness and thickness compared to spin-coated ones, favoring the potentiometric response. Also, their oxidation state, evaluated with cyclic voltammetry and UV-VIS spectroscopy, corroborates their sensing performance. The understanding of the structure-property relationship of the polymeric films affecting the pH detection is discussed based on the characteristics of the deposition method used.

Multiwalled CNTs/copper sulfide hybrids embedded in polyaniline thin films for near-infrared (NIR) photo detecting applications

Multiwalled CNTs/copper sulfide hybrids embedded in polyaniline thin films for near-infrared (NIR) photo detecting applications

Influence of structural disorder on the elastic, frictional, and electrical properties in functionalized polyaniline thin films at the nanoscale investigated by atomic force microscopy

We investigated the influence of structural order on the elastic, frictional, and electrical properties of butylthio-functionalized PANI (PANI-SBu) films by atomic force microscopy (AFM)-based techniques, including PeakForce quantitative nanomechanical mapping, friction force microscopy, and conductive AFM. The PANI-SBu films were prepared by the drop-cast method from the solution of PANI-SBu in N-methyl-2-pyrrolidone that was continuously stirred. The PANI-SBu films were fabricated after different solution stirring times. The shear force during the mechanical stir will disentangle the highly-coiled PANI-SBu polymer chains in the solution. Therefore, the polymer chains in solution cast on the substrates will progressively self-assemble into a more organized structure when solvents evaporate, leading to PANI-SBu films with improved structural order. Our AFM studies discovered that more structurally-ordered PANI-SBu films have substantially larger out-of-plane elastic moduli and charge mobility but smaller kinetic friction coefficients. The denser packing of polymer molecules increases film elasticities and promotes chain-to-chain charge transport. In addition, stiffer PANI-SBu film surfaces are more difficult to deform when sheared by the sliding AFM probe, resulting in less energy dissipation during AFM friction measurements. Thus, smaller kinetic friction coefficients were found. Conversely, more structurally-disordered PANI-SBu films have smaller elasticity and charge mobility but larger kinetic friction coefficients. Our results demonstrate that it is possible to manipulate the elastic, frictional, and electrical properties of PANI-SBu films by controlling their structural order, which can be essential for developing polymer-based composite materials and flexible electronic devices.

XRD Analysis of Polyaniline Thin Films Doped with Potassium Bromide and Picric Acid

The unique properties of conducting polymers not only provide great scope for their applications but also have led to the development of new models to explain their observed properties. Polyaniline has been the oldest among all the conducting polymers. Polyaniline has rapidly become the subject of considerable interest for physicists, chemists and material scientists. In this paper we have carried out the X-Ray Diffractional analysis of Polyaniline thin films doped with different concentrations (15% & 30%) of the dopants like Potassium Bromide and Picric Acid. The films has been prepared by using Vacuum Evaporation Technique and then characterized for XRD studies by using the X-Ray Diffractometer. The XRD studies reveals that the crystallinity of the doped polyaniline thin films has been increased with the increased doping concentration of the above said dopants which ensures its applications in the optoelectronic device technology.

Cyber Threat Detection Based On Artificial Neural Networks Using Event Profiles

Polyaniline has been the oldest among all the conducting polymers. The unique properties of conducting polymers not only provide great scope for their applications but also have led to the development of new models to explain their observed properties. Polyaniline has rapidly become the subject of considerable interest for physicists, chemists and material scientists. In this paper we have carried out the Scanning Electron Microscopy characteristics of Polyaniline thin films doped with different concentrations (15% & 30%) of the dopants like Potassium Bromide and Picric Acid. The films has been prepared by using Vacuum Evaporation Technique and then characterized for SEM studies by using Scanning Electron Microscopy unit. The SEM study reveals that the grain size increases with the increase in the concentration of the above said dopants which in turn increases the crystallinity of the material. This behavior ensures its application in the optoelectronic devices.