Conductive Polyaniline Polymer Research Articles

Electrochemical Sensors Based on Metal-Organic Framework and Conductive Polymer HKUST-1@PANI for High-Performance Detection of Lead Ions

In this research a highly microporous Cu-BTC (denoted as HKUST-1) was synthesized using a simple and rapid synthesis room temperature method. The as-prepared HKUST-1 obtained at room temperature for 10 min exhibited a very high Brunauer–Emmett–Teller (BET) surface area of 1875 m2/g, pore volume (Vp) of 0.789 cm3/g, and average micropore size of 7.84 Å. Based on this product, we successfully fabricated a conductive electrochemical sensor HKUST-1@PANI by polymerizing a conductive polyaniline polymer (PANI) around the metal-organic framework HKUST-1. Fourier transform infrared (FTIR) spectra, X-ray diffraction pattern (XRD) support the formation of HKUST-1@PANI. Furthermore, scanning electron microscopy (SEM) studies confirmed that PANI uniformly covered the surface of HKUST-1. We used the resulting material to build a new electrochemical sensor for the reliable detection of lead ions. The electrochemical response of the developed sensor towards ions was evaluated using differential pulse voltammetry (DPV). Under optimized conditions, linear detection was reproducible over the Pb2+ concentration range from 0.005 to 50 μM with a minimum detection limit of 5 nM. The sensor is practically usable in a wide variety of environments, as it is virtually immune to interference from other coexisting ions.

A new method in the synthesis of conductive polymers; synthesis, characterization, and investigation of photocatalytic properties of polyaniline.

As known, in the synthesis of conductive polyaniline polymer from aniline monomer, the polymerization medium must be acidic. In order to make the polymerization medium acidic, protonic acids such as HCl and H2SO4 are generally used. In this study, two acids have been used to make the polymerization medium acidic. One of them, as we know, is H2SO4 as a protonic acid. The other acid is the zinc ion, which is a Lewis acid. The metal ion has never been used for this purpose up to now. Two polyaniline polymers have been synthesized to prove that conductive polymers can also be synthesized in the presence of metal ions instead of protonic acid. One of them is the polyaniline polymer, synthesized in the presence of H2SO4(PANI). The other polymer is polyaniline polymer, synthesized in the presence of zinc ions as acid (PANI-Zn-PSS). The synthesized polymers have been characterized by using scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), X-ray diffraction diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), Ultraviolet-visible spectrophotometer (UV-vis.), thermal analysis techniques (thermo-gravimetric analysis, TGA)/differential thermal analysis, DTA) and electrical conductivity measurements kit. The photocatalytic activities of polymers synthesized have been investigated by the degradation of methylene blue (MB) dye in aqueous medium under UV light.

Solar‐Driven Co‐Production of Hydrogen and Value‐Add Conductive Polyaniline Polymer

AbstractTo reduce the reliance on fossil fuel, H2, as a clean fuel, has attracted substantial research and development activities in recent years. The traditional water splitting approach requires an applied bias of more than 1.5 V and the use of ion‐selective membranes to prevent the formation of a potentially explosive H2–O2 gas mixture, resulting in increased cost and system design complexity. Here, a solar‐driven H2 production process requiring a much lower applied bias of 1.05 V is reported whereby aniline (ANI) is oxidized to polyaniline (PANI) at the anode with a yield of 96% and H2 evolution reaction occurs at the cathode with a faradaic efficiency of 98.6 ± 3.9%. The process has multiple advantages including the elimination of ion‐exchange membrane as PANI is a solid product that also is of substantially higher value than O2. For demonstration, a single junction perovskite solar cell and low‐cost earth abundant CoP catalyst are successfully applied for this process. This process contributes to the advancement of solar‐driven low‐cost H2 generation coupled with co‐production of a high‐value product expediting the transition to a hydrogen economy.

Enhanced electromagnetic wave dissipation features of magnetic Ni microspheres by developing core-double shells structure

Readily oxidization of magnetic particles is a common drawback of these type of materials which reduce their electromagnetic wave dissipation performance. In this study, the magnetic core-double shells structured (Ni/SiO 2 /Polyaniline) composite has been developed for protection of the core from oxidation and in consequent improvement the complex permittivity. Solvothermal and in-situ polymerization methods were utilized for decorating Ni micro-particles with SiO 2 and conductive polyaniline polymer respectively. All physico-chemical, magnetic and electromagnetic features were evaluated via XRD, FTIR, XPS, FESEM, VSM and VNA analysis. The double shells composite possesses significant performance in terms of reflection loss and effective absorption bandwidth. The results reveal that the maximum dissipation capacity of the double shells composite is – 32.5 dB at 16.5 GHz with 4.5 GHz effective absorption bandwidth and 1.5 mm thickness. Enhancement in microwave dissipation features are arises from synergistic influence of various phenomena such as interfacial polarization, multiple Debye relaxation, natural ferromagnetic resonance and proper impedance matching characteristic. Overall, developing double shells structure on magnetic Ni microsphere particles had a meaningful effect on tuning the microwave absorption performance.

Electronic Structure Reconfiguration of Self-Supported Polyoxometalate-Based Lithium-Ion Battery Anodes for Efficient Lithium Storage.

Polyoxometalate (POM)-based materials are considered as promising candidates for lithium-ion batteries (LIBs) due to their stable and well-defined molecular structure and reversible multielectron redox properties. Currently, POM-based electrode materials suffer from high interfacial resistance and low uniformity. Herein, we reported a self-supported POM-based anode material for LIBs by electrodepositing H3PMo12O40 (PMo12) and aniline on carbon cloth (CC) for the first time. The as-prepared polyaniline (PANi)-PMo12/CC composite exhibited an excellent reversible capacity of 1092 mA h g-1 for 200 cycles at 1 A g-1. Such an outstanding performance was attributed to the rapid electron transfer and Li+ diffusion stemming from the exposure of more active sites by the self-supported structure, the strong electrostatic interaction, and electronic structure reconfiguration between the active PMo12 cluster and conductive PANi polymer. This work provides insight into the electronic structure engineering of highly efficient LIB anode materials.

Steel protection in acidified 3.5% NaCl by novel hybrid composite of CoCrO3/polyaniline: Chemical fabrication, physicochemical properties, and corrosion inhibition performance

Perovskite-type oxide (CoCrO3) was used as a core content of the material to synthesize oxide/PANI nanocomposite. The introduced composite was synthesized by two steps; oxide formation followed by in situ polymerization to cover the oxide surface by the conductive polyaniline polymer (PANI). The as-prepared oxide/PANI material was studied in terms of FE-SEM, TEM, XRD, FT-IR, BET, and XPS analyses. These characterization tools indicate the successful synthesis of a material having oxide and PANI as a composite material. The corrosion protection performance of an oxide/PANI material in a comparison with individual PANI was tested for carbon steel 1018 (CS-1018) in acidified 3.5% NaCl solution. The corrosion protection capacity was determined by LPR corrosion rate, Eocp-time, EIS, and PDP tools. The CoCrO3/PANI composite exhibited high protection capacity around 98.8% at the concentration of 150 mg/L and acted as a mixed type inhibitor i.e., inhibited both anodic and cathodic reactions. The adsorption behavior obeyed the Langmuir isotherm model with competitive physical and chemical adsorption. Surface morphology using FESEM/EDX measurements confirmed the high efficiency of the fabricated CoCrO3/PANI composite on the protection CS-1018 in acidified brine. It was observed that transition metal oxide (CoCrO3) nanoparticles reinforce the barrier and anticorrosive characteristics of PANI. The attained findings indicate that the prepared stabilized system (CoCrO3/PANI composite) is an outstanding inhibitor for CS-1018 corrosion in acidic solutions containing chloride.

Boosting the catalytic efficiency of platinum nanoparticles supported on pristine carbon nanotubes: Synergistic effects of conducting polymers

An advanced energy conversion catalyst comprising pristine carbon-nanotubes and conductive polyaniline polymer successfully synthesized and characterized for high temperature and non-humidified polymer electrolyte membrane fuel cells. The fabricated polyaniline-based catalyst shown a good distribution of platinum nanoparticles (Pt-NPs), and displayed an electrochemical surface area of 645 cm2/mgPt. The catalyst indicated remarkable catalytic activity towards the oxygen reduction reaction (ORR). The overpotential of ORR, the open-circuit voltage, and the power density of the polyaniline-based catalyst declined by a 30 mV, increased by a 50 mV, and enhanced by 26.5%, respectively, when compared to the polybenzimidazole-based catalyst. The impedance measurements have emphasized the improved catalytic activity and the enhanced fuel cell performance of the polyaniline-based catalyst, showing a remarkable reduction of 45% in the charge transfer resistance. This study revealed the advantages of using polyaniline as an anchor to improve the Pt-catalytic activity, opening the door for the wide applications of hydrogen energy.

Fe2O3/Fe3O4/PANI/MWCNT nanocomposite with the optimum amount and uniform orientation of Fe2O3/Fe3O4 NPs in polyaniline for high microwave absorbing performance

The purpose of this study was to develop a method that modifies the surface of carbon nanotubes with magnetic nanoparticles. The well-known conductive polyaniline polymer (PANI) was directly polymerized on the surface of the Fe2O3/Fe3O4 hybrid NPs and the Fe2O3/Fe3O4/PANI nanocomposite was obtained. Then, multi-walled carbon nanotubes (MWCNTs) were decorated with the specific weight ratio of Fe2O3/Fe3O4/PANI nanocomposites. The scanning electron microscopy of the final product (Fe2O3/Fe3O4/PANI/MWCNT nanocomposite) shows that the main area of CNT’s surface was decorated with individual or small clusters of Fe2O3/Fe3O4 NPs. Although, in some areas (probably at the extremities and on surface defects) can be seen large clusters of Fe2O3/Fe3O4 NPs. Transmission electron microscopy images demonstrate the uniform distribution of Fe2O3/Fe3O4 NPs, which are dispersed in the PANI background, overlapping the surface of the CNTs. The saturation magnetization of Fe2O3/Fe3O4/PANI/MWCNT nanocomposite as expected is 25% smaller than that of Fe2O3/Fe3O4/PANI nanocomposite, due to the presence of nonmagnetic MWCNT. However, Fe2O3/Fe3O4/PANI nanocomposite shows excellent absorption performance and effective bandwidth between 4 and 8 GHz. At the matching thickness of 3.2 mm, the loss of reflectance reaches its highest value, −88.8 dB at 10.6 GHz. The broadest effective bandwidth is larger than 8 GHz, between 9.7 and 18 GHz for 3 mm thick.

Direct Solar Charging of an Organic-Inorganic, Stable, and Aqueous Alkaline Redox Flow Battery with a Hematite Photoanode.

The intermittent nature of the sunlight and its increasing contribution to electricity generation is fostering the energy storage research. Direct solar charging of an auspicious type of redox flow battery could make solar energy directly and efficiently dispatchable. The first solar aqueous alkaline redox flow battery using low cost and environmentally safe materials is demonstrated. The electrolytes consist of the redox couples ferrocyanide and anthraquinone‐2,7‐disulphonate in sodium hydroxide solution, yielding a standard cell potential of 0.74 V. Photovoltage enhancement strategies are demonstrated for the ferrocyanide‐hematite junction by employing an annealing treatment and growing a layer of a conductive polyaniline polymer on the electrode surface, which decreases electron–hole recombination.

Direct Solar Charging of an Organic–Inorganic, Stable, and Aqueous Alkaline Redox Flow Battery with a Hematite Photoanode

AbstractThe intermittent nature of the sunlight and its increasing contribution to electricity generation is fostering the energy storage research. Direct solar charging of an auspicious type of redox flow battery could make solar energy directly and efficiently dispatchable. The first solar aqueous alkaline redox flow battery using low cost and environmentally safe materials is demonstrated. The electrolytes consist of the redox couples ferrocyanide and anthraquinone‐2,7‐disulphonate in sodium hydroxide solution, yielding a standard cell potential of 0.74 V. Photovoltage enhancement strategies are demonstrated for the ferrocyanide‐hematite junction by employing an annealing treatment and growing a layer of a conductive polyaniline polymer on the electrode surface, which decreases electron–hole recombination.

Electron Transport in in Situ and Ex Situ Electroactive Microbial Biofilms

Here we report on studies of microbial extracellular electron transport (EET) through Geobacter sulfurreducens biofilms. Electrical conductivity measurements were performed in situ on living biofilms in growth medium, and ex situ on biofilms removed from medium at various states of hydration. Previous in situ conductivity measurements revealed a peak-shaped dependency of G. sulfurreducens biofilm conductivity on gate potential, consistent with EET occurring via a redox-gradient driven, multi-step hopping mechanism (i.e., redox conduction).1-3 The in situ measurements reported here further indicate that conductivity increases with increasing temperature in an Arrhenius manner with an apparent activation energy of 0.13 eV, consistent with hemes of cytochromes acting as the electron transport cofactors.1 In the case of the ex situ measurements reported here, conductivity was shown to have a strong dependence on the biofilm hydration state. When the water content of the sample chamber was maintained at a fixed value, biofilm conductivity decreased by three orders of magnitude (10-1 to 10-4 µS/cm) when the temperature was increased from 12 to 35°C, as biofilms were expected to dehydrate. Alternatively, when the relative humidity of the testing chamber was increased from 25% to 85% at a fixed temperature, biofilm conductivity increased by more than three orders of magnitude, as biofilms were expected to rehydrate. For fully hydrated biofilms immersed in water, we observed an Arrhenius-like temperature dependence with a similar conductivity (1 µS/cm) and activation energy (0.14 eV) to that observed for the in situ measurements (5 µS/cm and 0.13 eV). These results suggest that in the case of the ex situ measurements, biofilm electrical conductivity becomes limited by charge compensating ionic conductivity, which is expected to decrease with decreasing biofilm water content. This conclusion was further corroborated by electrochemical impedance spectroscopy. Polymer films were used as controls (an Os-based redox polymer, a semiconducting benzotriazole polymer, and a conductive polyaniline polymer) to verify our methods and to find a comparable system for G. sulfurreducens biofilms. The G. sulfurreducens biofilms films behaved most similarly to the Os-based polymer, a known redox conductor. The results presented here indicate that G. sulfurreducens biofilms are a redox active material with tunable conductivity based on the hydration state of the film. Additionally, preliminary results suggest that the conductivity of the biofilm can be altered electrochemically and this property is currently under further study.

Development of label-free impedimetric platform based on new conductive polyaniline polymer and three-dimensional interdigitated electrode array for biosensor applications

Novel label-free impedimetric platform based on a three-dimensional interdigitated electrode array (3D-IDEA) sensor and new conductive polymer as a transducer for oxidoreductases is introduced. This platform is cost-effective, simple to construct and miniaturize. Monomer of conductive polymer N-(N’,N’-diethyldithiocarbamoylethylamidoethyl) aniline (AnD) was deposited onto 3D-IDEA by chemical polymerisation. It was found that the polymer film resistance depends on the redox-potential of the solution. For the first time polyAnD was used as enzyme immobilisation matrix. Pyrroloquinolinequinone (PQQ) dependent alcohol and glucose dehydrogenases were immobilized on 3D-IDEA covered with polyAnD by two different methods. 3D-IDEA sensors with enzymes, which were immobilised by physisorption on polyAnD layer, showed specific response in the presence of 1μM of the corresponding substrates. Obtained results revealed that PQQ dependent dehydrogenases can re-oxidize on polyAnD via direct electron transfer (DET) from enzyme active site to the polymer surface. This process can be monitored by methods of electrochemical impedance spectroscopy (EIS) and chronoamperometry. Presented study shows that EIS method gives a useful tool for research of re-oxidation process and interaction of electroactive enzymes with conducting materials giving information required to construct and develop analytical devices.

Removal of textile dyes from aqueous solution by conducting polymer modified clinoptilolite

In this work, clinoptilolite was modified with conducting polyaniline polymer and then the nanocomposite was used as an adsorbent for methyl orange (MO) as a model dye. Cations located in clinoptilolite structure like Na+, K+, Mg2+, Ca2+ were exchanged with anilinium cations and then the polymerization of anilinium cations in and outside of the clinoptilolite channels resulted in the formation of polyaniline/clinoptilolite nanocomposite. The resulted nanocomposite was used for the removal of MO from aqueous solution. The effect of various factors like contact time, concentration of dye as well as the amount of adsorbent on the removal efficiency of dye was investigated. The adsorption isotherms were investigated. It was found that the equilibrium adsorption data were well described by the Langmuir isotherm model. The kinetic studies indicated that the adsorption process was controlled by pseudo-second-order equation. High adsorption capacity and low contact time as well as the low cost of modified clinoptilolite proved that it is an efficient adsorbent for the removal of MO from aqueous solutions.

Pitting corrosion protection of low nickel stainless steel by electropolymerized conducting polymer coating in 0·5 M NaCl solution

Conducting polymers of polyaniline (PANi) and poly(o-phenylenediamine) (PoPD) were electropolymerized by cyclic voltammetric technique on low nickel stainless steel (LN SS) in H2SO4solution containing aniline and o-phenylenediamine monomers. The coatings were characterized by Fourier transform infrared spectroscopy, UV-visible and scanning electron microscopic techniques and the results are discussed. The corrosion protective properties of PANi and PoPD coatings on LN SS in 0·5 M NaCl were evaluated using potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) techniques. The potentiodynamic polarization and electrochemical impedance spectroscopic results indicate that the PoPD coating inhibits the corrosion of LN SS in 0·5 M NaCl solution more effectively than PANi.

Dielectric and magnetic properties of conducting ferromagnetic composite of polyaniline with γ-Fe 2O 3 nanoparticles

The present paper reports the synthesis of conducting polyaniline polymer composite with nanoclusters of ferrite (γ-Fe 2O 3) particles in the presence of dodecylbenzene sulfonic acid in aqueous medium through electrochemical and chemical oxidative polymerization. Different formulations have been prepared to study the effect of ferrite constituent on the electrical and dielectric properties of polyaniline nano-composite. Vibrating sample magnetometer (VSM) studies and electrical conductivity measurements have revealed that conducting polymer composite has a saturation magnetization ( M s) value of 48.9 emu g −1 and conductivity of the order of 0.13 S cm −1. The particle size of γ-Fe 2O 3 was found in the range of 8–15 nm as analyzed by transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FTIR) results have shown the presence of characteristic band stretching of Fe O band at 630 and 558 cm −1, indicating the presence of γ-Fe 2O 3 in the polyaniline matrix which is in agreement with the electrochemical results. Dielectric measurements have shown decreasing trend of dielectric constant with the increase of γ-Fe 2O 3 particles in the polymer matrix while shielding effective (SE) of −11.2 dB was achieved for the polymer composite in 8.2–12.4 GHz (X-band) frequency range. The characterization of the composite was further carried out by X-ray diffraction, UV–vis and thermal gravimetric analysis (TGA).

Infrared reflection of conducting polyaniline polymer coating

The infrared reflective behavior of a “coating–glass–coating” system, i.e. a glass plate with double conducting polyaniline polymer coatings, was investigated by experiments and theoretical calculations. A measurement method for the extinction coefficient of the polyaniline polymer coating on the glass plate with double coatings is given. The infrared reflectance of the coating is dependent on its thickness, and increases when the thickness increases. The rate of increase reduces when the thickness of the coating is greater than 2 μm. The infrared reflectance of the coating is almost independent of the thickness of the glass plate substrate over the range from 1 mm to 25 mm. However, it is highly dependent on the refractive index of the glass. Generally, it increases with the increase in the refractive index of the glass. The thickness of the coating should be greater than its minimum thickness, i.e. its penetration depth of electromagnetic waves. The minimum thickness is around 1 μm for the polyaniline polymer coatings.