Polyaniline Nanowires Research Articles

A sensitive and flexible sensor enhanced by constructing graphene-based polyaniline conductive networks

A sensitive and flexible sensor with dissimilar 3D conductive networks was fabricated by coating reduced graphene oxide (RGO) and polyaniline (PANI) on warp-knitted polyester-spandex fabric. In this study, the average length of 40∼80um 1D PANI rods or 2∼10um 1D PANI nanowires combined with 2D RGO sheet, forming 3D conductive networks. First the graphene oxide (GO) sheets was coated on the surface of fabric, then the GO was reduced to RGO, and the PANI array with ordered shapes was prepared on the surface of RGO fabric by self-assembled method and using sodium dodecyl benzene sulfonate (SDBS)/hydrochloric acid (HCl) or HCl as dopants. It could be found that the obtained 3D conductive network mainly presents two morphologies, one is nanorods-sheet shape (1:90 SDBS/HCl concentration ratio), and the other is nanowires-sheet shape (HCl 1 mol/L). The results show that the fabric with 3D nanorods-sheet conductive network exhibits outstanding conductivity (resistance = 0.228 KΩ/sq), strain sensitivity, wide strain sensing range (tolerable strain up to 100 %), and repeatability (withstand 500 stretching-releasing tests), precisely detecting human motion in flexible wearable devices.

Improving the stability of Pb2+ ion-selective electrodes by using 3D polyaniline nanowire arrays as the inner solid-contact transducer

Polyaniline nanowire arrays (PANI- NWA) were synthesized by electrochemical deposition, then successfully applied as the ion-to-electron transducer in ion selective electrodes (ISEs) for the detection of aqueous Pb2+ ions. When used as the solid-contact layer in Pb2+-ISEs, the PANI- NWA delivered a high capacitance and low impedance as measured by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively, thus delivering efficient ion-to-electron transfer. Owing to the open structure of the nanowire arrays, Pb2+ ions can able to easily penetrate the PANI layer, further enhancing the detection efficiency. Developed GC/PANI- NWA/Pb2+-ISE showed outstanding potentiometric performance, including a low Pb2+ detection limit (2.5 × 10−8 M), a short response time (about 1 s), high stability in N2 (or O2) and no light sensitivity. Further, the water layer between the solid-contact layer and the ISM was largely eliminated when three-dimensional PANI- NWA were applied as the solid contact layer, thus enhancing the stability of the ISE.

Mn-Co bimetallic phosphate on electrodeposited PANI nanowires with composition modulated structural morphology for efficient electrocatalytic water splitting

Bifunctional electrocatalysts for total water splitting (TWS) applications are vital for the substantial production of hydrogen energy. Herein, we have reported an efficient manganese and cobalt bimetallic phosphate electrocatalyst synthesized on an electrodeposited PANI nanowire array for TWS. The hierarchical morphology and higher Mn3+ and Co2+/Co3+ ratio on catalyst surface enhance faster charge transfer kinetic rate for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). We achived a lower overpotential of 109 mV and Tafel value of 99 mV/Dec for HER application, whereas Mn1.5Co1.5 showed an excellent OER performance with overpotential of 254 mV and Tafel value of 36 mV/Dec. Further, the fabricated electrolyzer achieved a cell voltage of 1.54 V to attain a density of 10 mA/cm2 with an impressive durability of 40 h at 100 mA/cm2. This work presents a promising approach for designing TMP-based electrocatalyst along with use of PANI nanowires for efficient bifunctional TWS.

Synthesis of polyaniline nanowires wrapped yolk-shell structured S@RGO composite material and its improved lithium-storage performance

To accommodate volume change of sulfur particles, confine lithium polysulfides (LiPSs) within conductive matrix, as well as accelerate transference of electrons/ions, the sulfur@reduced graphene oxide (S@RGO) yolk-shell particles wrapped by polyaniline (PANI) nanowires were prepared in this work. Meanwhile, PANI nanowires are synthesized by in situ polymerization of aniline monomers. Importantly, many nanoscale holes are generated on the RGO nanosheets forming three-dimensional channels for ion transportation within the obtained composite material. LiPSs can be firmly confined in the composite material by the polar oxygen-containing groups on the surface of the RGO shells and the protonated nitrogen-containing groups on the PANI nanowires. Benefiting from the unique structure, the S@RGO/PANI particles exhibit an improved electrochemical performance. It can deliver an initial capacity of 1021 mAh·g−1 at 0.1C rate and a high initial coulombic efficiency up to 95.4%. Even at 2.0C rate, a discharge capacity of 501 mAh·g−1 can be retained after 500 cycles. Results indicate that the S@RGO/PANI can be promisingly exploited as a kind of high-energy density cathode material for rechargeable lithium batteries.

Electrochemical Biosensor with Enhanced Antifouling Capability for COVID-19 Nucleic Acid Detection in Complex Biological Media.

Biofouling caused by the accumulation of biomolecules on sensing surfaces is one of the major problems and challenges to realize the practical application of electrochemical biosensors, and an effective way to counter this problem is the construction of antifouling biosensors. Herein, an antifouling electrochemical biosensor was constructed based on electropolymerized polyaniline (PANI) nanowires and newly designed peptides for the detection of the COVID-19 N-gene. The inverted Y-shaped peptides were designed with excellent antifouling properties and two anchoring branches, and their antifouling performances against proteins and complex biological media were investigated using different approaches. Based on the biotin–streptavidin affinity system, biotin-labeled probes specific to the N-gene (nucleocapsid phosphoprotein) of COVID-19 were immobilized onto the peptide-coated PANI nanowires, forming a highly sensitive and antifouling electrochemical sensing interface for the detection of COVID-19 nucleic acid. The antifouling genosensor demonstrated a wide linear range (10–14 to 10–9 M) and an exceptional low detection limit (3.5 fM). The remarkable performance of the genosensor derives from the high peak current of PANI, which is chosen as the sensing signal, and the extraordinary antifouling properties of designed peptides, which guarantee accurate detection in complex systems. These crucial features represent essential elements for future rapid and decentralized clinical testing.

Bovine Serum Albumin-Cross-Linked Polyaniline Nanowires for Ultralow Fouling and Highly Sensitive Electrochemical Protein Quantification in Human Serum Samples.

Biofouling represents a serious challenge for the assaying of disease markers with various biosensors in complex biological samples due to the accompanied nonspecific protein adsorption. Herein, a highly sensitive and antifouling biosensing interface was constructed based on a cost-effective inert protein bovine serum albumin (BSA) cross-linked with polyaniline nanowires (PANI-NWs). Compared with the physically adsorbed BSA that was commonly used to block nonspecific adsorption or binding of proteins, the cross-linked BSA exhibited a significantly enhanced antifouling capability. The BSA/PANI-NW-modified electrode interface possessed excellent antifouling capability and electrochemical activity owing to the presence of the cross-linked BSA and the conducting polymer polyaniline. With further immobilization of the peptide aptamer for immunoglobulin G (IgG) recognition onto the BSA/PANI-NW interface, an electrochemical biosensor with excellent selectivity and sensitivity was prepared. The IgG biosensor possessed a linear range from 1.0 ng mL-1 to 10 μg mL-1 and a low detection limit of 0.27 ng mL-1, and it was capable of assaying IgG in complex human serum samples with acceptable accuracy when compared with the assay results obtained using commercial enzyme-linked immunosorbent assay kits. It is expected that the unique BSA-cross-linked conducting polymers can be used for the construction of various electrochemical sensors and biosensors that can be applied in complex biological media.

Ethylenediaminetetra Acetic Acid Functionalized Polyaniline Nanowires: Organic Field Effect Transistor for the Detection of Hg2+

In recent decades, electronic sensors based on field effect transistors (FETs) have been broadly explored because of their high sensitivity and rapid detection. Among these sensors, FET sensors based on nanomaterials and nanowires have shown immense potential for the detection of a wide span of analytes. In the present investigation, polyaniline nanowires (PANI NWs) were synthesized by a two-step galvanostatic method and functionalized with EDTA (ethylenediaminetetra acetic acid). The organic field effect transistor (OFET) based on polyaniline nanowires (PANI NWs) functionalized with EDTA (ethylenediaminetetra acetic acid) was used for detection of Hg2+ ions. The detection ability of the OFET has been investigated by immersing a top-gate electrode in an aqueous solution with various Hg2+ ions concentrations. An increase in the drain current of the OFET was observed by the addition of incremental amounts of Hg2+ ions. The limit of detection (LOD) for this device is 0.1447 ppb with a sensitivity of 0.766 mA/ppb in a concentration window of 1 ppb to 15 ppb. The obtained relative standard deviation (RSD) for reproducibility and repeatability of the device was 7.898% and 14.22%, respectively.

A Flexible Electromagnetic Interference Shielding Fabric Prepared by Construction of PANI/MXene Conductive Network via Layer‐by‐Layer Assembly

AbstractThe electromagnetic interference (EMI) shielding textiles accomplishing high‐level EMI protective performance and wear comfort has been designed and developed. 1D polyaniline nanowires and 2D transition metal carbide/carbonitride nanosheets are loaded on the carbon fiber fabric via a layer‐by‐layer (L‐b‐L) assembly approach to fabricate a functional layer and followed with a polydimethylsiloxane (PDMS) coating. The resultant fabric exhibits a high electrical conductivity of ≈325 S m−1 and the EMI shielding effectiveness ≈35.3 dB with only 0.376 mm thickness. Benefiting from the hydrophobic effect of thin PDMS film, a satisfactory self‐cleaning performance with a large contact angle of 135.2° is achieved. Furthermore, favorable flexibility, air permeability (346 mm s−1), and thermal management further broaden the field of practical application. This work can provide a new solution for next‐generation EMI shielding materials in view of the comprehensive performance.

Reticulated polyaniline nanowires as a cathode microporous layer for high-temperature PEMFCs

Traditional dense microporous layers (MPLs) are suitable for low-temperature proton exchange membrane fuel cells (PEMFCs), but they greatly hinder mass transport in high-temperature PEMFCs. Here, we report a novel cathode MPL based on reticulated polyaniline nanowires that were grown on carbon paper via in-situ electropolymerization. The maximum power density of the high-temperature PEMFC based on the new MPL was 476 mW/cm2, which was 36% higher than that based on a conventional MPL. Oxygen gain tests and electrochemical impedance spectroscopy showed that the new MPL accelerated oxygen transfer due to its unique pore size distribution, which ultimately improved the performance of the HT-PEMFC.

Nitrogen-doped nanoporous graphene induced by a multiple confinement strategy for membrane separation of rare earth.

SummaryRare earth separation is still a major challenge in membrane science. Nitrogen-doped nanoporous graphene (NDNG) is a promising material for membrane separation, but it has not yet been tested for rare earth separation, and it is limited by multi-complex synthesis. Herein, we developed a one-step, facile, and scalable approach to synthesize NDNG with tunable pore size and controlled nitrogen content using confinement combustion. Nanoporous hydrotalcite from Zn(NO3)2 is formed between layers of graphene oxide (GO) absorbed with phenylalanine via confinement growth, thus preparing the sandwich hydrotalcite/phenylalanine/GO composites. Subsequently, area-confinement combustion of hydrotalcite nanopores is used to etch graphene nanopores, and the hydrotalcite interlayer as a closed flat nanoreactor induces two-dimensional space confinement doping of planar nitrogen into graphene. The membrane prepared by NDNG achieves separation of Sc3+ from the other rare earth ions with excellent selectivity (∼3.7) through selective electrostatic interactions of pyrrolic-N, and separation selectivity of ∼1.7 for Tm3+/Sm3+.

Electrochemical detection of white spot syndrome virus with a silicone rubber disposable electrode composed of graphene quantum dots and gold nanoparticle-embedded polyaniline nanowires

BackgroundWith the enormous increment of globalization and global warming, it is expected that the number of newly evolved infectious diseases will continue to increase. To prevent damage due to these infections, the development of a diagnostic method for detecting a virus with high sensitivity in a short time is highly desired. In this study, we have developed a disposable electrode with high-sensitivity and accuracy to evaluate its performances for several target viruses.ResultsConductive silicon rubber (CSR) was used to fabricate a disposable sensing matrix composed of nitrogen and sulfur-co-doped graphene quantum dots (N,S-GQDs) and a gold-polyaniline nanocomposite (AuNP-PAni). A specific anti-white spot syndrome virus (WSSV) antibody was conjugated to the surface of this nanocomposite, which was successfully applied for the detection of WSSV over a wide linear range of concentration from 1.45 × 102 to 1.45 × 105 DNA copies/ml, with a detection limit as low as 48.4 DNA copies/ml.ConclusionThe engineered sensor electrode can retain the detection activity up to 5 weeks, to confirm its long-term stability, required for disposable sensing applications. This is the first demonstration of the detection of WSSV by a nanofabricated sensing electrode with high sensitivity, selectivity, and stability, providing as a potential diagnostic tool to monitor WSSV in the aquaculture industry.

Degradation of epoxy coatings cooperated with polyaniline nanowires in the outdoor environment

Polyaniline (PANI)/epoxy composite coatings, as heavy‐duty corrosion protection coatings, might have great promise applications in marine and industrial environments. The weak weather resistance of epoxy resins, especially under the sunlight, directly reduces the service life of the epoxy composites coatings. Herein, the degradation behaviors of epoxy coatings with and without PANI nanowires in the outdoor environment were investigated by the multiple techniques and methods. The cracks occurred on the coating surface were observed by Field Emission Scanning Electron Microscopy, and the density change of the methyl group in the coatings was characterized by Attenuated Total Reflectance‐Fourier Transform Infrared spectroscopy. In addition, the mechanical properties including adhesion, hardness, flexibility and impact resistance of the coating were tested. The corrosion protection performance of epoxy coatings cooperated with and without PANI nanowires was investigated by Electrochemical Impedance Spectroscopy technique. A series of experimental results demonstrated that the degradation of the coating containing PANI nanowires was slowed down, which is attributed to that PANI nanowires served as the antioxidant and free radical scavenger in the epoxy coatings, and prolonged the service life of the epoxy resin.

Conductive elastic sponge-based triboelectric nanogenerator (TENG) for effective random mechanical energy harvesting and ammonia sensing

Abstract Triboelectric nanogenerator (TENG) based on elastic materials is increasing interests for irregular and random mechanical energies harvesting. However, the conductive design of the elastic materials in TENGs often limits its applications. Herein, a new conductive and elastic sponge-based triboelectric nanogenerator (ES-TENG) is developed for random mechanical energy harvesting, which integrates the elastic material and the conductive material on a flexible sponge to realize the collection of mechanical energies, particularly for irregular and random motions. The conductive elastic sponge is prepared by a simple dilute chemical polymerization of aniline to grow conductive polyaniline nanowires (PANI NWs) on the surface of elastic sponge. Due to the flexible deformation of sponge, it can harvest the kinetic energy of disordered motion with different amplitudes and from variable directions. As the triboelectric layer of ES-TENG, the porous sponge and polyaniline nanowires on its surface can provide a large contact area and improve the triboelectric efficiency. At the same time, the conductive polyaniline coating on the surface of sponge can also be used as the electrode of ES-TENG to conduct electrons and generate an output of 540 V and 6 μA respectively, which can be used on various flexible object surfaces to collect irregular and random mechanical energy ubiquitous in daily life. In addition, based on the NH3-sensing performance and the three-dimensional reticular structure of the polyaniline nanowires on the elastic sponge, the ES-TENG can make it work as self-powered sensor for detecting toxic NH3 with the detection limit up to 1 ppm and the response time less than 3 s. In view of the microporous and nanowire structures, elasticity, conductivity and easy fabrication of the conductive elastic sponge, the ES-TENG has promising applications in various irregular and random mechanical energy harvesting and self-powered NH3 sensors.

A Novel Polyaniline Nanowire Arrays/Three‐Dimensional Graphene Composite for Supercapacitor

AbstractIt is an effective way to obtain high performance supercapacitors by increasing the surface area and conductivity of electrode materials. In this paper, three‐dimensional (3D) graphene with a small pore size, good electrical conductivity and high mechanical strength is fabricated by chemical vapor deposition using nickel nanoparticles as the template. Then, a polyaniline nanowire arrays (PANI NWAs)/3D graphene composite is fabricated by in‐situ polymerization. Due to the high conductivity and unique nano‐structure, the as‐prepared PANI NWAs/3D graphene composite exhibits an excellent capacitance of 680 F g−1 at current density of 1 A g−1. Moreover, a symmetric supercapacitor based on the PANI NWAs/3D graphene composite is assembled, and it shows an energy density of 6.43 Wh kg−1 at a power density of 0.4 kW kg−1. The assembled supercapacitor also exhibits a good cycling stability, which retains 78 % of its initial specific capacitance after 1000 cycles.

Antifouling and anticorrosion performance of the composite coating made of tetrabromobisphenol-A epoxy and polyaniline nanowires

Tetrabromobisphenol-A epoxy (TBEP), based on its hydrophobicity and antibacterial activity, is suitable to prepare top coating. Meanwhile, bisphenol-A epoxy (EP), based on its strong adhesion strength with metals, is a commonly material to prepare primer coating. Polyaniline (PANI) nanowires, which can facilitate the formation of passivation layer, is usually used as additive to reinforce the corrosion resistance of coatings. Herein, the composite coating composed of EP primer coating with 2 wt% PANI nanowires and TBEP top coating with 2 wt% PANI nanowires was assembled and characterized. Because the hydrophobic and antibiotic bromine atoms existed in TBEP, the composite coating exhibited low water absorption (0.32 wt%) and high antibacterial rate (over 93.17 %) compared with pure EP coating. Moreover, the composite coating had good adhesion with metals (dry: 5.65 MPa, wet: 4.07 MPa) and excellent anticorrosion properties (|Z|0.01 Hz ＞ 1011 ohms·cm2 after 70 days immersion) in comparison to the composite coating without PANI nanowires, since the PANI nanowires provide multifunctional behaviors such as passivation, barrier, etc. This work might give a new perspective to prepare efficient antifouling and anticorrosion coating via reasonably combine the advantages of different functional materials.

High-performance chemiresistor-type NH3 gas sensor based on three-dimensional reduced graphene oxide/polyaniline hybrid

In this study, a novel gas sensor is proposed based on a three-dimensional reduced graphene oxide/polyaniline (3D RGO/PANI) hybrid, which is synthesized by a hydrothermal method for detecting NH3 gas at room temperature. The 3D RGO/PANI hybrid is characterized by field emission-scanning electron microscopy, Fourier transform infrared and x-ray diffraction. The specific surface area is analyzed using the Brunauer–Emmett–Teller (BET) equation. The as-synthesized sensing materials with an appropriate amount of polyaniline nanowires (PANI-NWs) can effectively prevent aggregation of the neighboring graphene sheets and directly act as adsorption sites for NH3 molecules. In comparison with its pure 3D RGO counterpart, the 3D RGO/PANI (1:1) hybrid exhibits 44.7 times enhanced response to 100 ppm NH3, suggesting the remarkable effect of PANI-NWs in improving the sensitivity. This work gives new insights into boosting the sensitivity and selectivity of detecting NH3 gas by incorporating PANI-NWs into 3D RGO.

All Pseudocapacitive Nitrogen-Doped Reduced Graphene Oxide and Polyaniline Nanowire Network for High-Performance Flexible On-Chip Energy Storage

The rapid progress of wearable and portable electronics demands high-performance on-chip energy storage units. However, it is still challenging to fabricate high-energy and flexible microscale ener...

In situ generation of carbonized polyaniline nanowires on thermally-treated and electrochemically-etched carbon fiber cloth for high efficient solar seawater desalination

Utilizing solar energy to evaporate water is an environment-friendly and promising approach for various applications such as seawater desalination. Various photothermal materials can be developed for evaporating water, however, there are still some drawbacks such as complicated synthesis processes, weak/narrow absorbance, bulkiness, and low evaporation rate, which severely limit their commercial applications. Herein, we reported the preparation of electrochemically-etched carbon fiber cloth with surface-coated carbonized polyaniline nanowires (ECFC/CPANW) based on thermally-treated pre-oxidized polyacrylonitrile fiber cloth for highly efficient solar steam generation. This ECFC/CPANW composite has the advantages of low thermal conductivity, effective broadband solar absorption, good hydrophilicity and water transfer ability. When ECFC/CPANW and polyurethane foam are bound together as a solar evaporator, ECFC/CPANW achieved the highest vaporization efficiency of up to 93.7% under 1 sun illumination, which is more efficient than those of most materials previously reported. Therefore, this kind of photo-thermal conversion material with low cost, good stability and environmental friendliness could envision promising practical application for water treatment.

The performance of epoxy coatings containing polyaniline (PANI) nanowires in neutral salt, alkaline, and acidic aqueous media

AbstractPANI/epoxy coatings have great promise applications in the industry as the metal corrosion protection coating, and their performance directly determines the life span of the coating and equipment durability. In this study, the performance of epoxy coatings with and without PANI nanowires immersed in 12 wt% NaCl, 5 wt% HCl, and 5 wt% NaOH solutions at different temperature were investigated for the first time. The performance and the degradation reactions of the coating cooperated with PANI nanowires were characterized by the variety of techniques and methods, including ultraviolet–visible spectrophotometry (UV–vis), field emission scanning electron microscopy (SEM), Attenuated Total Reflectance‐Fourier transform Infrared spectroscopy (ATR‐FTIR), and thermogravimetric analysis (TGA). The experiment results indicated that the failure mechanism of the different coatings varied with the different temperatures and solutions. Electrochemical impedance spectra (EIS) results showed that an appropriate content of PANI nanowires improve the protection performance of epoxy coatings in 12 wt% NaCl, 5 wt% HCl, and 5 wt% NaOH solutions, which is attributed to the passivation ability and shielding effect of PANI nanowires.

Silver Nanoparticles Decorated Polyaniline Nanowires-Based Electrochemical DNA Sensor: Two-step Electrochemical Synthesis

In this work, silver nanoparticles decorated onto polyaniline nanowires were synthesized site-specifically onto Pt working electrodes (with only 0.8 mm2 area) using a novel, rapid, and effective electrochemical procedure: electropolymerization of PANi NWs and electrodeposition of AgNPs. The complementary properties of PANi NWs and AgNPs were obtained, including high surface area, high electrochemical activity, high biocompatibility, high chemical stability and good adhesion with the electrode surface. Obtained results showed advantages of the electrosynthesis method compared to traditional methods, which have difficulties in binding between modifying materials with electrode surfaces. The sensor surface modification with the PANi NWs/AgNPs material facilitated the probe DNA immobilization and improved the electrochemical signal of the DNA sensors. The detection limit of the sensors was 2.80 × 10−15 M. The DNA sensors exhibited advantages including direct detection, high sensitivity, good specificity, and potential miniaturization for development of lab-on-a-chip systems.