Reduced Graphene Oxide Polyaniline Research Articles

Reduced graphene oxide-polyaniline hybrid nanocomposite for selective sensing of ammonia gas at room temperature

A binary solvent system (DMSO + water) assisted swollen liquid crystalline lamellar mesophase (SLCLM) template is effectively used to produce the reduced graphene oxide-polyaniline (rGO-PANI) nanocomposite. The large surface area and 2D hybrid nanosheets of PANI and rGO collectively persuade, providing an anchor for the ammonia gas sensing process. The obtained gas sensing results demonstrate the synthesized rGO-PANI films exhibited the highest gas sensitivity, excellent repeatability, good linear gas concentration response, a low detection limit (200–1000 ppb), and an ultrahigh sensitivity of 32 %. The newly synthesized morphology of rGO-PANI nanocomposite may be one of the factors for the enhanced NH3 gas response. All characterization techniques, such as XRD, HR-TEM, XPS, FT-IR, and Raman spectroscopy, confirm the formation of the rGO-PANI hybrid nanocomposite. Furthermore, the NH3 gas sensitivity in the relative humidity range of 34 %–57 % showed only ∼1 % variation. The development of 2D nanosheets of hybrid rGO-PANI nanocomposite in SLCLM with enhanced gas sensing properties is significant for the future development of selective and sensitive RT ammonia sensors.

Composite nanoarchitectonics with reduced-graphene oxide and polyaniline for a highly responsive and selective sensing of methanol vapors

In an approach to develop room temperature, highly responsive and selective methanol gas sensor, reduced graphene oxide-polyaniline nanocomposites have been successfully synthesized through simple chemistry based chemical oxidative synthesis process in the presence of camphor sulfonic acid. Field emission scanning electron microscopy, Raman spectroscopy, and X-ray diffraction, respectively, were used to examine the morphological, vibrational, and structural characteristics of synthesized samples systematically. The morphology of prepared samples was observed as nanoparticles and structure as semi-crystalline in nature. Raman spectra of synthesized samples exhibit all essential bands that confirm the growth of expected samples. Thereafter, these samples were studied as sensors for the detection of 50, 100, 150 and 200 ppm levels of methanol vapors. It was found that 8 wt% reduced graphene oxide doped polyaniline composite exhibits the highest response (%) i.e., 52% at 200 ppm. Furthermore, these sample showed good stability even after 180 days of fabrications. To understand the response of these composites, a sensing mechanism is also discussed. Our results shows that reduced graphene oxide doped polyaniline-based gas sensors showed high response, selectively towards Methanol vapors. Moreover, prepared sensors showed appreciable stability, reproducibility and repeatability making them suitable candidates for commercial production of methanol vapor sensors.

Versatile sensing capabilities of layer-by-layer deposited polyaniline-reduced graphene oxide composite-based sensors

Precise temperature, humidity, and organic pollutants monitoring are required for industrial, environmental and medical applications. The interesting properties of polyaniline for sensors, such as environmental responsiveness and stability, combined with the large surface area and tunable properties of graphene oxide, offer excellent prospects for the development of sensor materials. In this paper, we show that HCl-doped polyaniline/reduced graphene oxide (PANI/rGO) layer-by-layer deposition and subsequent reduction can be used as resistive sensors for temperature, humidity, acetone, and electrochemical sensors for organophosphate detection in aqueous solutions. Sensors were characterized using atomic force and scanning electron microscopies and energy-dispersive x-ray and Raman spectroscopies, and impedance spectroscopy complemented by semi-empirical quantum chemical calculations. Reduction temperature and bilayer numbers influence PANI/rGO sensor characteristics significantly. The results show that only one PANI/rGO bilayer is needed to provide a temperature coefficient of resistance of − 0.758 °C−1 and 37% sensitivity at 95% relative humidity. PANI/rGO shows potential for electrochemical detection of dimethoate affected by the number of bilayers and reduction temperature. The response to acetone vapor is linear from 1 to 60 ppm and detectable at 1 ppm. The sensors do not respond to methanol and some other volatile organic compounds (VOCs) at the same concentration. Food monitoring with total VOCs detection was successfully demonstrated. PANI/rGO sensors feature versatile sensing capabilities, making them feasible due to their rapid production and low cost.

Study on CePO4 modified PANI/RGO composites to enhance the anti-corrosion property of epoxy resin

This manuscript presents a modification method by using nanofillers for simultaneously improving the barrier and corrosion inhibition in epoxy coatings. In this method, polyaniline (PANI) nanofibers are first grown on reduced graphene oxide (RGO) using an in situ polymerization reaction, and then cerium phosphate (CePO4) nanograins are directly modified onto polyaniline/reduced graphene oxide (PANI/RGO) composites using a hydrothermal reaction. A new hydrophobic and corrosion-resistant PANI/RGO/CePO4 nanocomposite is successfully prepared. Physical and chemical characterization was performed by Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–Vis), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (SEM). PANI/RGO/CePO4 nanomaterials were compounded into epoxy resin and sprayed on Q235 carbon steel, and their corrosion resistance performance was tested by using AC impedance spectroscopy and salt spray tests. The results show that PANI/RGO/CePO4 nanocomposites improve the barrier properties of epoxy resin. In addition, X-ray photoelectron spectroscopy (XPS) before and after corrosion showed that the cerium ions and phosphate ions released from CePO4 in the composite had a corrosion inhibition effect. It forms cerium oxide and iron phosphate corrosion inhibition films on mild steel and cuts off direct contact between the electrolyte and the substrate. This nanomaterial-loaded epoxy coating can greatly improve the composite's anti-corrosion ability.

Nitrogen-doped reduced graphene oxide-polyaniline composite materials: hydrothermal treatment, characterisation and supercapacitive properties

High-temperature treatment increased the conductivity, carrier density and mobility of N-RGO. Inclusion of PANI tailored activities from capacitive to battery-like and diffusion-controlled.

Shearing induced ordered structures in two-dimensional nanomaterials-based electrodes for boosted pseudocapacitive kinetics

Two-dimensional (2D) nanomaterials have been extensively pursued as functional electrodes in electrochemical energy storage devices. Numerous efforts have been devoted to improving the electrochemical performance by engineering the chemical composition and structure of 2D nanomaterials, while little attention was paid to optimizing their electrode manufacturing by wet processing techniques. Herein, we study how the shear processing impacts the electrochemical performance of 2D nanomaterial-based electrodes using graphene oxide/polyaniline (GO/PANI) colloidal hydrogels as a model electrode slurry. The GO/PANI hydrogels are processed into reduced GO/PANI (RGO/PANI) membranes by blade casting followed by chemical reduction. The formation process and microstructure of the RGO/PANI membranes were revealed by rheology and synchrotron small-angle X-ray scattering. We find that a high shear rate in blade casting is favourable for inducing ordered alignment of the 2D nanosheet-like network structure of GO/PANI hydrogels, leading to the formation of stratified microstructure in the RGO/PANI membranes. The high shear-induced ordered structures greatly boost the pseudocapacitive kinetics of RGO/PANI membranes as flexible supercapacitor electrodes. Our findings highlight the significance of electrode processing of 2D nanomaterials for large-scale manufacturing for future industrial applications.

Designing highly transparent electropolymerized PANI/rGO nanocomposite as a Pt-free electrocatalytic layer in photoelectrochromic device for self-powered green building

The multifunctional device combining electrochromic and photovoltaic performance is defined as a photoelectrochromic device (PECD), which is designed for self-powered smart window applications. Conventionally, Pt is used as an electrocatalyst to reduce the I3− in the electrolyte of PECD. However, the optical contrast of PECD with Pt-based counter electrode (CE) is restricted by an intrinsic opaque. In view of this problem, a polyaniline/reduced graphene oxide (PANI/rGO) nanocomposite electrocatalytic layer with highly optical transmittance and good electrocatalytic performance is designed to replace conventional Pt-based CE for further improving the optical performance of the corresponding PECD. Based on the advantages of low cost and promising electrocatalytic activity of PANI, highly transparent and remarkable conductive rGO is introduced to further boost up its electrical conductivity and electrochemical performance. To embed the rGO into the matrix of PANI uniformly, PANI/rGO nanocomposite is deposited on the conductive glass of ITO via electropolymerization. After systematically optimizing the film thickness and composition of PANI/rGO nanocomposite, the PECD with optimized PANI/rGO based CE possesses better optical contrast (ΔT = 26.8%) than that with Pt-based CE (ΔT = 9.4%), which clearly reveals that PANI/rGO nanocomposites with high optical transparency and electrocatalytic ability have the great potential to replace traditional Pt CE in PECDs.

Wearable Self-Powered Smart Sensors for Portable Nutrition Monitoring.

Self-powered sensors have attracted great attention in the field of analysis owing to the necessity of power resources for the routine use of sensor devices. However, it is still challenging to construct wearable self-powered sensors in a simple and efficient way. Herein, wearable self-powered textile smart sensors based on advanced bifunctional polyaniline/reduced graphene oxide (PANI/RGO) films have been successfully developed for remote real-time detection of vitamin C. Specifically, a pH-assisted oil/water (O/W) self-assembly strategy was proposed to boost the O/W self-assembled PANI/RGO films via proton regulation. The as-obtained PANI/RGO films could be directly loaded on the textile substrate, with good capacitive and biosensing performance due to the multifunctionality of PANI and RGO, respectively. Moreover, both wearable power supply devices and wearable biosensors based on PANI/RGO films possess good electrochemical performance, which paves the way for the actual application of self-powered nutrition monitoring. Significantly, obvious signals have been obtained in the detection of vitamin C beverages, exhibiting promising application values in daily nutrition track necessities. Prospectively, this study would provide an effective and simple strategy for integrating wearable self-powered sensors, and the developed smart sensing system is an ideal choice for the portable detection of nutrition.

Fabrication of bi-functionalized nanocomposite coating for simultaneous improved thermal stability and corrosion protection performance based on polyaniline-reduced graphene oxide/organo-modified montmorillonite

ABSTRACT In this study, a bi-functionalization strategy for epoxy-based coatings was performed with the aim of simultaneously improving thermal stability and corrosion protection performance. For this purpose, organo-modified montmorillonite (OMMT) with hexadecyltriphenylphosphonium (HDTPP) and polyaniline-reduced graphene oxide (PANI-rGO) were synthesized and characterized by FTIR, XRD, SEM, AFM, and TGA analyses. Then, epoxy-based nanocomposite coatings loaded with different amounts of OMMT or/and PANI-rGO in four groups (EP, EP/OMMT, EP/PANI-rGO, and EP/OMMT/PANI-rGO) were prepared. The synergistic effects of OMMT and PANI-rGO, individually and simultaneously, on corrosion protection performance of various formulation of epoxy-based nanocomposite coatings was assessed by electrochemical impedance spectroscopy (EIS). From the given results, the epoxy coating containing 5 phr of OMMT and 0.5 phr of PANI-rGO can be introduced as the optimal sample of bi-functionalized nanocomposite coating, which remarkably improved the barrier performance of the epoxy coating.

Green synthesis for the functionalization of reduced graphene and polyanline as efficient super capacitor application

A chemical polymerization of aniline is followed by a hydrothermal self-assembly of PANI and a graphene oxide (GO) dispersion in this two-step synthesis of polyaniline reduced graphene oxide (PANI/rGO). The systematic investigation of the component's influence on the composite porous structure, morphology and chemical properties. PANI/rGO electrode materials with specified physical and chemical properties, when employed as electrode materials for supercapacitors operating in an aqueous electrolyte, showed high specific capacitance values and excellent cyclic stability. The results show that one of the most important factors impacting composite electrochemical performance is the chemical composition of the PANI/rGO. The hydrothermal technique provides a wide range of synthesis options for creating hybrids with desirable physical and chemical properties. Furthermore, the PANI/rGO electrodes did not require an additional binder, making the fabrication process easier, emphasising its potential for use in flexible or asymmetric supercapacitors.

Imperceptible Supercapacitors with High Area-Specific Capacitance.

Imperceptible electronics will make next-generation healthcare and biomedical systems thinner, lighter, and more flexible. While other components are thoroughly investigated, imperceptible energy storage devices lag behind because the decrease of thickness impairs the area-specific energy density. Imperceptible supercapacitors with high area-specific capacitance based on reduced graphene oxide/polyaniline (RGO/PANI) composite electrodes and polyvinyl alcohol (PVA)/H2 SO4 gel electrolyte are reported. Two strategies to realize a supercapacitor with a total device thickness of 5µm-including substrate, electrode, and electrolyte-and an area-specific capacitance of 36 mF cm-2 simultaneously are implemented. First, the void volume of the RGO/PANI electrodes through mechanical compression is reduced, which decreases the thickness by 83% while retaining 89% of the capacitance. Second, the PVA-to-H2 SO4 mass ratio is decreased to 1:4.5, which improves the ion conductivity by 5000% compared to the commonly used PVA/H2 SO4 gel. Both advantages enable a 2µm-thick gel electrolyte for planar interdigital supercapacitors. The impressive electromechanical stability of the imperceptible supercapacitors by wrinkling the substrate to produce folds with radii of 6µm or less is demonstrated. The supercapacitors will be meaningful energy storage modules for future self-powered imperceptible electronics.

Polyaniline-Reduced Graphene Oxide Nanosheets for Room Temperature NH3 Detection

In this report, we develop an additive-free synthesis for homogeneous graphene-based heterostructures by a facile method. A room temperature semiconductor material, reduced graphene oxide (rGO) dop...

Acetylcholinesterase sensor based on PANi/rGO film electrochemically grown on screen‐printed electrodes

AbstractIn this work, the polyaniline/reduced graphene oxide (PANi/rGO) bilayer was directly electrodeposited on carbon screen‐printed electrodes (SPE). Some details in growth of PANi/rGO bilayer were revealed from cyclic voltammograms and X‐ray photoelectron spectra. The growth of stacked rGO film at high compactness on the electrode surface is mainly accompanied with reduction of epoxy functional groups at basal planes of graphitic flakes. The as‐grown rGO layer with abundent hydroxyl functional groups at basal planes is preferable to attract intrinsic fibrillar‐like PANi polymer chains in protonated aqueous media. The as‐prepared PANi/rGO hybrid bilayer has shown good conductivity, high porosity, good adhesion to biomolecules, and fast electron transfer rate (increased by 3.8 times). Herein, PANi/rGO film has been further utilized to develop disposable acetylcholinesterase sensors able to detect acetylthiocholine (ATCh) with apparent Michaelis ‐ Menten constant of 0.728 mM. These sensors provide a very promising technical solution for in‐situ monitoring acetylthiocholine level in patients with neuro‐diseases and determination of neuro‐toxins such as sarin and pesticides.

Efficient Electrode Material based on Carbon Cloth Supported Polyaniline/Reduced Graphene Oxide Composites for Supercapacitor Application

Nowadays, world energy infrastructure is being stretched due to imbalance between energy production and energy consumption; renewable & sustainable energy storage and conversion techniques could resolve this issue. Thus global energy requirements, limited availability of fossil fuels and environmental crisis drive the expansion of alternative or non- conventional energy sources with high energy and power densities. Electrochemical capacitors or supercapacitors, with a combined form of high power density and energy density, have acquired a stunning acceptance towards the field of electrochemical energy storage. Supercapacitors are used in electric vehicles, mobile phones, digital cameras, wearable devices, portable devices and uninterruptible power supplies (UPS) etc. Here, we have reported the binder free carbon cloth supported polyaniline/reduced graphene oxide (PRGO) composite hydrogel as a high performance supercapacitor electrode synthesized by a facile chemical polymerization method using phytic acid (PA). The electrochemical performance of binder free carbon cloth based PRGO composite hydrogel electrode has been analysed using cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD) techniques. The high specific capacitance (C S ) ~ 235.32 F g -1 has been obtained for the PRGO composite hydrogel @cc in 1 M H 2 SO 4 . The electrochemical results show that the binder free carbon cloth based PRGO composite hydrogel electrode is a promising candidate for supercapacitors.

Covalently bonded polyaniline-reduced graphene oxide/single-walled carbon nanotubes nanocomposites: influence of various dimensional carbon nanostructures on the electrochromic behavior of PANI

In this paper, water-dispersible and covalently bonded polyaniline-carbon nanostructures, including polyaniline-reduced graphene oxide (PANI-rGO), polyaniline-single-walled carbon nanotubes (PANI-SWCNTs), and polyaniline-reduced graphene oxide/single-walled carbon nanotube (PANI-rGO/SWCNTs) nanocomposites, were synthesized by grafting PANI onto p-phenylenediamine (PPD)-functionalized graphene oxide (GO) or single-walled carbon nanotubes (SWCNTs) using polystyrene sulfonate (PSS) as a macromolecular dopant agent. The structures and morphologies of the PANI, PANI-rGO, PANI-SWCNTs, and PANI-rGO/SWCNTs nanocomposites were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The cyclic voltammetry and UV–vis spectra were performed on an electrochemical workstation and a UV–vis spectrometer, respectively. The results show that the electrochromic and electrochemical properties of nanocomposites can benefit from the high conductivity of SWCNTs and the abundant active sites of rGO. When SWCNTs and rGO work together, their respective shortcomings are overcome, allowing the nanocomposite to exhibit the best electrochemical and electrochromic properties. The optical contrast increased from 0.38 for PANI to 0.52 for PANI-rGO/SWCNTs. The coloring and bleaching times decreased from 2.59 s and 2.39 s, respectively, for PANI to 1.33 and 0.78 s, respectively, for PANI-rGO/SWCNTs. The charge transfer resistance (Rct) decreased from 135 Ω for PANI to 30 Ω for PANI-rGO/SWCNTs. The synergistic effect of PANI, rGO, and SWCNTs can significantly improve the electrochromic ability of PANI. Electrochromic properties of covalently bonded polyaniline-reduced graphene oxide/single walled carbon nanotubes nanocomposites. A high performance electrochromic material was prepared using polyaniline (PANI) and two different dimensional carbon nanostructures, single-walled carbon nanotubes (SWCNTs) and reduced graphene oxide (rGO) as the components. The covalent bond was introduced to interface between PANI and two carbon nanostructures to form a three-dimensional conductive network. Owing to the high electron conduction through directly connected covalent bond and loose molecular chain aggregation brought by two various dimensional carbon nanostructure, PANI-rGO/SWCNTs nanocomposites exhibit superior electrochemical and electrochromic properties (high optical contrast and short switching time) compared with PANI.

Design and Construction of Polyaniline/Reduced Graphene Oxide Three-Dimensional Dendritic Architecture on Interdigital Electrode for Sensitive Detection Nitrite

The polyaniline/reduced graphene oxide (PANI/RGO) modified interdigital electrode (IDE) has been successfully fabricated by in situ electrochemical reduction and electrochemical polymerization through cyclic voltammetry. The morphology and topography of PANI/RGO characterized by SEM and AFM display intercross-linked dendritic structure in three dimensions, and it is favorable for the detection of nitrite due to its large surface area, which can provide the large electrocatalytic active surface and various diffusion paths for nitrite. Herein, the obtained PANI/RGO/IDE was employed for the electrochemical monitoring platform of nitrite for the first time and the electrochemical performance of the as-developed sensor was investigated via cyclic voltammetry and chronoamperometry. At the optimum conditions, the PANI/RGO/IDE has a linear response in the range from 0.4 to 183.7 mM with a sensitivity of 457.4 μA mM−1 cm−2 and a detection limit of 0.1 μM. Moreover, the obtained PANI/RGO/IDE with excellent long-term stability and reproducibility also can be employed for practical application for the determination of nitrite in tap water, the results show that the recovery rate is desirable. It is expected that IDE can be employed as the substrate electrode decorated with various materials to construct high-performance electrochemical sensors.

Electrochemically prepared three-dimensional reduced graphene oxide-polyaniline nanocomposite as a solid-phase microextraction coating for ethion determination

Here, a three-dimensional reduced graphene oxide-polyaniline nanocomposite was synthesized and applied as a sorbent for solid-phase microextraction of ethion from water samples followed by negative corona discharge ionization ion mobility spectrometry. The nanocomposite was synthesized via a fast and facile two-step electrochemical method. The prepared sorbent was characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy and thermogravimetric analysis. The main experimental parameters in the preparation of the fiber including concentration of graphene oxide, electrodeposition time, aniline concentration, and electropolymerization time were investigated. Also, parameters affecting the extraction process (i.e., salt addition, sample stirring rate, solution pH, extraction temperature and extraction time) were studied. Under the optimal conditions, the linearity and limit of detection were found to be 1.0–70 and 0.4 μg L−1, respectively. The method presented good precision (intra-day and inter-day, n = 3), ranged from 1.7 to 4.7%. The analyte recovery obtained using spiked real water samples were in the range of 84–98%.

Utilizing polyaniline to decorate graphene and its effect on the electrochemical properties of polyaniline/graphene electrode composite

A mature and efficient process for the preparation of polyaniline/ reduced graphene oxide (PANI/rGO) composite as supercapacitor electrode material was designed at a low cost. The composite was synthesized by in situ polymerization of monomer aniline in the suspension of reduced graphene oxide (rGO). The cross-link polyaniline (PANI) nanofibers to form a framework distributed on the rGO surface was confirmed by analytical tests. The such framework structure would enable electrolytes to access the internal surface, which was beneficial to the electrochemical performance. The rGO with large surface area was help to ions diffusion and the PANI with active sites was beneficial to redox reaction. Combined the double layer capacitance of rGO and pseudocapacitance of PANI, the PANI/rGO composite exhibited higher specific capacitance and better properties than individual PANI or rGO. The maximum specific capacitance of the composite was 285.4 F g−1 at the scan rate of 5 mV s−1 in 1 M Na2SO4 electrolyte. This work presented a convenient and efficient method to synthesize the PANI/rGO composite as the electrode material for supercapacitors.

The Propagation of the Conducting Zone of Layer‐by‐Layer PANI‐rGO Composite Films

AbstractThe layer‐by‐layer polyaniline‐reduced graphene oxide (PANI‐rGO) films with the thickness of micron and millimeter level are prepared by a simple method. The electrochemical performances of the films are carried out by cyclic voltammetry and chronoamperometry. In micron level films, rGO promotes the propagation of the conducting zone of PANI‐rGO films. The micron level PANI‐rGO film resistance is reduced 10 times than that of pure PANI film. The specific capacitance can be up to 1000 F⋅g−1. However, the films with millimeter thickness have no such role. The specific capacitance is only one fifth of the micron level thickness film. This is due to the lossing of electroactive PANI in the film. And the amount of rGO in the PANI‐rGO composite and the thickness of the films have no effect on the oxidation activation energy of PANI.

Simultaneous electro-synthesis of polyaniline graphene nanocomposite in dilute graphene oxide as dopant and aniline by electrochemical method and its high specific capacitance

A composite of reduced Graphene oxide -polyaniline (RGO-PANI) was fabricated by an in situ electrochemical oxidative polymerization of aniline in the presence of GO in Sodium dodecyl sulfate (SDS), which synthsized by anodic exfoliation, on carbon paper electrode. Here GO uses as a protonation agent for doping of PANI and also as a physical crosslinker of PANI fibers. The structure and the property of RGO-PANI composite were investigated by tunneling electron microscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, cyclic voltammetry, galvanostatic charge–discharge test and electrochemical impedance spectroscopy (EIS) techniques. The fabricated composite was then employed as the supercapacitor, which provides specific capacitances as high as 890 F g−1 at the current density of 1 A g−1 in 1 M H2SO4 aqueous solution. Long term stability and high specific capacitance, are related to synergistic effects between PANI and RGO and also conductive graphene sheets. EIS indicates a decreasing charge transfer resistance at the electrode/electrolyte interface of RGO-PANI composite than each individual component. This work may suggest an alternative method to synthesis one-pot produce of RGO-PANI composite for the development of high-performance supercapacitors.