Graphene Polyaniline Composites Research Articles

Facial preparation of covalent modified reduced graphene oxide/polyaniline composite and its stable-enhanced electrochemical performance

Graphene-polyaniline composites have captured extensive attention because of their outstanding performance during the electrochemical process, while their practical applications are limited due to the complex and uncontrollable preparation process. This work provides a simple and controllable preparation route, in which covalent modified reduced graphene oxide (E-RGO) is successfully prepared by ethylenediamine (EDA) and graphene oxide (GO), and E-RGO with different degrees of modification is obtained by adjusting the amount of EDA during the preparation process, and then in situ polymerization of aniline monomer is used to produce E-RGO/PANI in E-RGO suspension. Among them, E-RGO-12 has a relatively stretched sheet, which provides a large support surface for the subsequent in-situ polymerization of aniline and increases the utilization rate of graphene. The PANI network is tightly wrapped on the surface of E-RGO, forming a “PANI-(E-RGO)-PANI” lamellar structure and the single components are connected by covalent bonds and have a strong conjugation effect. The rough surface of the E-RGO/PANI composite and the pores in the PANI network are conducive for the electrochemical process, which increases the active site of electrode reaction, and thus improve the electron transfer rate. E-RGO-12/PANI exhibits superior property with the specific capacitance of 398 F/g at 0.6 A/g, and after the current density changes to 6 A/g, the specific capacitance retention rate is 64.8%. After 2000 cycles, the capacitance retention rate is 76.4%. The current work provides a green and efficient new idea for reducing graphene oxide and preparing E-RGO/PANI composite materials for the energy storage device.

A simple procedure for fabricating graphene or modified graphene polyaniline composites for supercapacitor application

The depleting fuel resources and elevated air pollution are raising serious concerns among the global population. The fuel prices are also increasing day by day. Hence the world is more focused on maximizing conventional energy resources like solar, tidal, wind energies, etc. However, for the fullest utilization of conventional energy sources, we need efficient energy storage systems, and currently, we are using batteries as the primary energy storage elements. Nowadays, researchers are giving utmost importance to the development of supercapacitors. Graphene coming under carbon groups and polyaniline (PANI), coming under electronic conducting polymers (ECP), are two different materials mainly used for supercapacitor electrode fabrication. The normal route for synthesizing graphene-PANI composites is a time-consuming process. Here we present a simple route for synthesizing graphene-PANI composites. The same method can be adopted for fabricating modified graphene-PANI composites too. The FTIR, Raman spectroscopy, XRD, SEM, and TEM results showed that the formation of graphene-PANI composites in the current route is the same as that of the normal method. Moreover, the cyclic voltammetry (CV) and charge–discharge (CD) tests revealed excellent electrochemical performance and cyclability. The CV study reported that the specific capacitances of the supercapacitor are 235, 179, 120, 85, and 55 F/g at scan rates of 10, 20, 50, 100, and 200 mV/s.The capacitance retention ratio was more than 90% and the ESR was found to be 10.5 O.

Binder free platinum nanoparticles decorated graphene-polyaniline composite film for high performance supercapacitor application

Conventional supercapacitors use insulating binders with active materials for fabricating working electrodes. Use of such binder reduces electrical conductivity of the electrode, thus causing energy wastage of supercapacitor. To overcome this, herein, we report binder free Platinum (Pt) nanoparticles (NPs) decorated Graphene–Polyaniline (Gr-PANi) composite modified electrode for supercapacitor application. Pt decorated Gr-PANi composite was prepared by template-free electrochemical polymerization method followed by electro-deposition of Pt NPs. Detailed structural and chemical characterization of the composite were done by SEM, EDX spectroscopy and Raman scattering. FESEM image of Pt decorated Gr-PANi composite revealed nano-fibrous structure of PANi (average diameter of 50–100nm) with Pt NPs uniformly deposited on its surface. Interconnected network of PANi nanofibers made matrix highly porous, thereby, providing an improved electrode/electrolyte interface area and shorter diffusion lengths for electrolytic ions. The electrochemical behavior of Pt NPs decorated Gr-PANi composite film was studied by cyclic voltammetry while galvanostatic charge–discharge measurements were carried out to investigate its capacitive performances. Pt decorated Gr-PANi composite based supercapacitor exhibited higher specific capacitance of 922.5F/g which was∼1.75 folds greater than that of only Gr-PANi based electrode at same current density (1A/g) and much higher than previously reported Gr-PANi composite based supercapacitors. The developed Pt decorated Gr-PANi composite modified electrode exhibited charge capacity of 0.57 mAh/cm2 and discharge capacity of 0.29 mAh/cm2 which were 2.4 folds and 1.81 folds higher than only Gr-PANi electrode respectively. The significant improvement in specific capacitance with excellent sustainability to higher current, superior rate capability, charge storage capacity and cycling stability can be attributed to the synergistic effect of electrical double-layer capacitance and pseudocapacitance resulting from Gr and PANi respectively and excellent catalytic ability of Pt NPs. The as-synthesized Pt decorated Gr-PANi composite offers simple, promising and binder free electrode material for energy storage devices.

Graphene–Polyaniline composite based ultra-sensitive electrochemical sensor for non-enzymatic detection of urea

Detection of urea is of prime importance in food and water safety, dairy industries and environmental monitoring. Traditional methods to detect urea are either expensive and involve sophisticated instrumentation or are based on enzymatic approach of detection. Herein, we report a Graphene-Polyaniline (Gr-PANi) based electrochemical sensor for non-enzymatic detection of urea. Gr-PANi composite was synthesized by electro-deposition of PANi on the surface of Gr modified GCE using cyclic voltammetry (CV) technique. The presence of Gr and PANi in the composite was confirmed using a multitude of characterization techniques which included FESEM, XRD and Raman spectroscopy. The electrochemical behavior of urea at the surface of Gr-PANi modified GCE was studied by CV whereas urea sensing was performed by using simple current-potential (I–V) technique. The current response of the as-fabricated urea sensor was∼4.74 folds greater than that of pure PANi based sensor and ∼67.2 times greater than that of pure Gr based sensor. The sensing performance of the composite based urea sensor was optimized by varying the thickness of PANi film. The optimized sensor exhibited lower limit of detection (5.88μM), excellent reproducibility, selectivity and stability with an enhanced sensitivity of −226.9μA/μM cm2 (R2=0.993) in the range of 10μM–200μM. The reliability of the as-fabricated sensor was successfully investigated by using it to detect urea concentrations in samples of tap water and milk samples. This highly-sensitive Gr–PANi composite based urea sensor provides a simple, low cost, non-enzymatic approach for detection of urea that find numerous applications in clinical diagnostics, dairy industries, fertilizer plants and environmental monitoring.

Facile synthesis of shape-controlled graphene–polyaniline composites for high performance supercapacitor electrode materials

The shape-controlled graphene–PANI nanocomposites showing excellent performance as supercapacitor electrode materials were successfully prepared by a facile hydrothermal method without any surfactants.

A sensitive voltammetric sensor based on synergistic effect of graphene–polyaniline hybrid film for quantification of calcium antagonist lercanidipine

ABSTRACTA chemically modified sensor based on the synergistic effect of graphene and polyaniline for electrochemical sensing of calcium antagonist lercanidipine (LCP) has been developed. Scanning electron microscopy, electrochemical impedance spectroscopy, square‐wave voltammetry, and cyclic voltammetry were utilized to characterize the morphology and electroanalytical performance of the fabricated sensor. Under optimized conditions, reduction peak current was linear over the wide concentration range from 5 to 125 ng mL−1 with correlation coefficient of 0.9998. The limit of detection and the limit of quantification were found to be 1.94 and 5.89 ng mL−1. The developed sensor also exhibited good reproducibility and long‐term stability. In addition, the proposed method was successfully applied to the determination of LCP in pharmaceutical formulation which is proved by recovery studies. Graphene–polyaniline composites are expected to be promising material for biosensing applications because of the ease of fabrication, excellent electrochemical performance, and high electroactive surface area. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40959.

Fibers coated with a graphene-polyaniline nanocomposite for the headspace solid-phase microextraction of organochlorine pesticides from seawater samples

We have prepared a fiber for solid-phase microextraction of organochlorine pesticides. A graphene-polyaniline composite was electrochemically deposited on a platinum fiber by exploiting the unique properties of polyaniline and graphene. The modified fiber displays thermal stability up to 320 °C and can be used more than 70 times. It possesses high extraction efficiency due to the high specific surface of graphene. The Pt fiber was used for the extraction and subsequent GC determination of the pesticides heptachlor, aldrin, endrin and p,p’-DDT in aqueous samples. The effects of extraction time, extraction temperature, stirring rate, salinity and headspace volume were optimized. Calibration plots are linear (with an R2 of 0.990) in the 0.2 to 250 μg L–1 concentration range, and the limits of detection are below 11 ng L–1 (at an S/N of 3). The relative standard deviations for three replicate measurements with a single fiber were <11.0 %. The recovery of the pesticides from spiked seawater samples ranged from 81 % to 112 %.

Electrochemical immunosensor based on graphene–polyaniline composites and carboxylated graphene oxide for estradiol detection

A novel estradiol immunosensor based on graphene–polyaniline (GR–PANI) composites and carboxylated graphene oxide (GO) was developed. GR–PANI composites were used to enhance the electroactivity and stability of the electrode. The current response of the immunosensor was remarkably improved due to the synergistic effects of GR and PANI. Horseradish peroxidase–graphene oxide–antibody (HRP–GO–Ab) conjugates which were constructed by using the carboxylated GO as the carrier of the antibody and horseradish peroxidase as the label improved the catalytic activity for hydrogen reduction of the electrode. A competitive immunoassay was facilitated between 17β-estradiol and the HRP–GO–Ab conjugates. Based on this competitive immunoassay, the immunosensor showed a wide linear response to estradiol in the range 0.04–7.00ng/mL and a limit of detection of 0.02ng/mL (S/N=3). The developed immunosensor was successfully applied to the detection of estradiol in real samples.

Synthesis and Electrochemical Performance of Graphene/Polyaniline

Graphene/polyaniline composites (GP) were prepared from aniline and graphite oxide using an electrochemical method.The structure characterization and surface morphology were investigated using X-ray diffraction (XRD),scanning electron microscopy (SEM),Raman spectroscopy,and X-ray photoelectron spectroscopy (XPS),and its electrochemical properties were measured.The results show that the composite keeps the basic morphology of graphene and that the polyaniline particles are uniformly dispersed.The specific capacitances of the composite materials reach 352 and 315 F·g-1 at 500 and 1000mA·g-1,respectively,higher than those of graphene and polyaniline.The majority (90%) of the capacitance remains after 1000 cycles of charge and recharge at 1000m A·g-1.The composite shows potential for use in supercapacitors.

‘Bridge’ effect of CdS nanoparticles in the interface of graphene–polyaniline composites

A facile method for preparing graphene–polyaniline composite is proposed without the necessity of using graphene oxide. By adding CdS nanoparticles into the in situ polymerization system consisting of graphene and aniline monomers, a graphene–polyaniline composite with a well-bonded interface is yielded. It is found that the nano-CdS particles act as a ‘bridge’, connecting (i) PANI via the electrostatic force of attraction between the electron clouds of the sulfur and nitrogen atoms and (ii) graphene by π–π stacking. Taking advantage of the effective interfacial interactions, a large enhancement (∼400%) of the photoelectronic performance in the composite is observed. The work opens up a path for maintaining the original structure and properties of graphene during graphene–polymer composite manufacturing.

Preparation of graphene–polyaniline composites by simple chemical procedure and its improved field emission properties

Graphene–polyaniline composites have been synthesized using simple chemical procedure in two different ways (i) by mixing of the pre-synthesized graphene and polyaniline nanofibers and (ii) by in situ polymerization in presence of graphite oxide followed by further reduction. Detailed optical spectroscopic studies of the synthesized composites along with the pristine polyaniline nanofibers were performed by Fourier transformed infrared spectroscopy and UV–vis spectroscopy. The structural and morphological characterizations were performed by X-ray diffraction, transmission electron microscope measurements and field emission scanning electron microscope measurements, respectively while the chemical characters were studied by X-ray photoelectron spectroscopic measurement. The graphene–polyaniline composite retained the photoluminescence property of the as synthesized polyaniline nanofibers. The electron field emission property of the composite showed marked improvement compared to pristine polyaniline fibers with a turn-on field as low as 3.91 V/μm at a current density of 1 μA/cm 2. The field enhancement factor was found to be 7012 which is much higher for the case of a polymer based composite.