Incorporation Of GO Research Articles

The Corrosion Behavior of Zn/Graphene Oxide Composite Coatings Fabricated by Direct Current Electrodeposition

The zinc (Zn) and Zn/graphene oxide (Zn/GO) composite coatings on the mild steel were fabricated by direct current electrodeposition from an acidic chloride bath without GO and that with four different concentrations (50, 100, 200 and 300 mg/L) of GO, respectively. The GO first is synthesized by using the typical Hummer method. Physical characterizations including the surface and cross-sectional morphology, chemical composition and crystal structure of the Zn and Zn/GO composite coatings were done by scanning electron microscope, energy-dispersive x-ray and x-ray diffraction. The crystalline size, texture coefficient, water contact angle and hardness of the Zn and Zn/GO composite coatings were measured. The corrosion behavior of the Zn and Zn/GO composite coatings was studied by the electrochemical corrosion tests including the potentiodynamic polarization test and the electrochemical impedance spectroscopy test and the immersion test. The result reveals that the corrosion resistance of the Zn coating is remarkably increased by the incorporation of GO. Furthermore, it does not show a linear increase with the increase in the amount of incorporated GO and an optimal corrosion resistance is provided by the Zn/GO composite coating attained from the electrolyte containing 100 mg/L GO. The influence of the incorporation of GO on the corrosion resistance of the Zn coating is explained in combination with their physical characterizations.

Tribological investigation of Ni-graphene oxide composite coating produced by pulsed electrodeposition

Nickel-graphene oxide (GO) nanocomposite coatings with a uniform grain distribution were prepared on the SS440 samples and SS ball surface by pulsed electrodeposition (PED) method. The morphology, compositional, and tribological properties were investigated. FE-SEM and AFM microscopic studies shows a homogenous presence of GO particles intercalated in the Ni matrix in the composite coating. The incorporation of GO into the Ni matrix reduced the water contact angle of the coating showing its hydrophilic nature. XRD, EDS, and Raman spectra also confirmed the presence of GO on the coating surface as well as inside the matrix. The tribological studies show that the trapped GO particles positively affect the friction and wear resistance of the coating through formation of a tribo film in the contact interface. The effect of sliding speed on COF and wear rate of the pristine Ni coating was compared with Ni-GO composite coating and the insertion of GO into Ni matrix is found to reduce the coefficient of friction and wear depth of the coating substantially. With increasing sliding speed, the wear depth is almost 10 times lesser than pristine Ni, thus indicating its antiwear characteristics after intercalation of GO particles in the Ni matrix.

Enhanced electrochemical performance for sensing Pb(II) based on graphene oxide incorporated mesoporous MnFe2O4 nanocomposites

In order to seek for high performance electrochemical sensing materials toward heavy metal ions with excellent electrical conductivity, high adsorption capacity and good electrocatalytic activity, in this study, graphene oxide was incorporated with mesoporous MnFe2O4 (MnFe2O4/GO) to fabricate an electrochemical platform for sensing Pb(II). The as-prepared mesoporous MnFe2O4/GO nanocomposites contained uniformly MnFe2O4 particles with the diameter about 400 nm. The maximal pore diameter of MnFe2O4/GO was 4.5 nm and its specific surface area was obviously increased from 167.0 m2 g−1 to 285.7 m2 g−1 with the incorporation of GO. The CV, EIS and SWASV response toward Pb(II) showed the incorporation of GO would enhance the electrochemical activity of MnFe2O4 due to the improvement of specific surface area, electrocatalytic activity and conductivity supported by GO sheets. It provided the sensitivity of 33.9 μA/μM and LOD of 0.0883 μM for electrochemical detection toward Pb(II), and it was even suitable for the selective detection of Pb(II) in the presence of Zn(II). This MnFe2O4/GO modified electrode also presented satisfying reproducibility, stability, repeatability and applicability for detection of Pb(II). In short, it provides a simple and promising platform to develop novel electrochemical sensor for detecting heavy metal ions with high performance.

Preparation and the swelling properties of sodium alginate graft poly (acrylic acid‐co‐2‐acrylamide‐2‐methyl propane sulfonic acid)/graphene oxide hydrogel composite

AbstractSodium alginate graft poly (acrylic acid‐co‐2‐acrylamide‐2‐methyl propane sulfonic acid)/graphene oxide (SA‐g‐P(AA‐co‐AMPS)/GO) hydrogel composite is prepared. The composite is characterized by infrared (IR) spectroscopy, X‐ray diffraction (XRD), high‐resolution scanning electron microscope (HRSEM), and differential scanning calorimetry (DSC). The swelling properties of the composite are investigated. GO acts as part of the cross‐linking points, which improves the swelling property of the composite. Maximal amount of absorption capacity in water and 0.9% NaCl is 862.3 and 164.7 g/g, respectively, with a GO content of 5 wt% of total mass of monomers. However, the absorption of water and 0.9% NaCl is only 390.3 and 52.5 g/g, respectively, without the incorporation of GO. Water retention properties of the composite are also tested.

Reinforcing effect of graphene oxide reinforcement on the properties of poly (vinyl alcohol) and carboxymethyl tamarind gum based phase-separated film.

The current study deals with the preparation and the characterization of the PVA-CMT-GO films. The PVA-CMT film was translucent in nature and smooth to touch. The addition of GO resulted in the formation of agglomerated structures. XRD studies suggested that the incorporation of GO increased the average crystallite size. The mechanical properties of the films as determined by stress relaxation studies suggested that all the films were viscoelastic in nature. The drug release study showed a decrease in the amount of the drug release with the increase in the GO content. The PVA-CMT-GO films (without drug) showed certain degree of antimicrobial activity owing to the inherent antimicrobial property of GO. The drug loaded films also showed good antimicrobial property. It was found that the prepared films altered the cell proliferation of the human skin keratinocytes in a composition-dependent manner.

Construction of Perovskite Solar Cells Using Inorganic Hole-Extracting Components.

A NiOx–graphene oxide (NiOx–GO) hybrid has been prepared by a simple solution-processed method and was used as hole-extraction material in perovskite solar cells with either gold or carbon as back contact electrode. The impact of GO content on the optoelectronic behavior of NiOx and the photovoltaic performance of the fabricated devices has been studied. Thus, GO incorporation showed a significant improvement in the performance of NiOx-based devices. The best attained efficiency was 13.3%, and it was 45% higher than that with pure NiOx. This is attributed to a significant improvement in the hole extraction, recombination resistance, and energy-level matching in comparison to pure NiOx. In addition, NiOx–GO/Au-based perovskite solar cell devices showed a negligible hysteresis effect and high reliability and repeatability. When carbon was used as back contact electrode, the obtained efficiencies were lower, but it leaves space for improvement. Devices based on inorganic hole transporters NiOx or NiOx–GO demonstrated higher stability in ambient air compared to a standard cell based on spiro-OMeTAD.

Investigation on Electrochemical Properties of Polythiophene Nanocomposite with Graphite Derivatives as Supercapacitor Material on Breath Figure-Decorated PMMA Electrode

Breath figures have been formed by the direct breath figure method on polymethyl methacrylate electrode sand hexagonal oriented holes with 0.5- to 10-μm2 surface area have been created. Deposition of materials on the electrodes has been performed by the spray-coating method. polythiophene (PTh) nanoparticles, polythiophene-graphene oxide (PTh-GO) and polythiophene-reduced graphene oxide (PTh-G) nanocomposites were synthesized by emulsion polymerization, while characterization of synthetic materials have been carried out by Fourier transform infrared, Χ-ray diffraction, transmission electron microscopy, UV–Vis spectroscopy and field emission scanning electron microscopy techniques. Also, the electrochemical properties of the designed electrodes were investigated by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy techniques. Specific capacitance of porous electrodes coated by PTh nanoparticles, PTh-GO and PTh-G nanocomposites were calculated from cyclic voltammetry curves at 5 mV/s scan rate, andthe values are 3.5 F/g, 16.39 F/g, and 28.68 F/g, respectively. Also, the energy density of each electrode at 5 mV/s scan rate has been calculated and the results show that incorporation of GO and G nanolayers with PTh nanoparticles enhances the electrochemical properties of electrodes.

Highly aligned graphene oxide/waterborne polyurethane fabricated by in-situ polymerization at low temperature

AbstractNanocomposites of waterborne polyurethane (WPU) containing graphene oxide sheets (GO) were prepared by an in-situ polymerization method at low temperature. The morphology and interface structure were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Without undergoing complicated functionalization processes, GO can be finely embed into a WPU matrix and present high degree of orientation at high GO contents, due to the formation of chemical bonds and hydrogen bonding. From the Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and dynamic mechanical analysis (DMA) results, incorporation of GO exists in two ways and shows inverse effects. At a content of 2.0 wt.% GO loading, the tensile elastic modulus of the GO-WPU film increased by 193% to neat WPU. The nanocomposites also displayed 30°C higher thermal stability than WPU in thermogravimetric (TG) curves. This environment-friendly method may pave the way to design graphene-based polymer composites.

Effect of graphene oxide on the adsorption properties of ordered mesoporous carbons toward H2, C6H6, CH4 and CO2

Graphene oxide/ordered mesoporous carbon (GO/OMC) nanostructures with narrow mesopore size distribution were obtained via soft-templating synthesis followed by KOH activation. Microporosity and mesoporosity of these composite nanostructures were additionally controlled by adjusting the amount of added GO and by post-synthesis KOH activation. Incorporation of GO into OMC structure resulted in improving adsorption uptakes of benzene and hydrogen, which reached 9.6 mmol/g (at 20 °C and pressure close to the saturation vapor pressure) and 11.7 mmol/g (2.3 wt% H2 at −196 °C and 760 mm Hg), respectively. At the same conditions bare activated OMC adsorbed 8.1 mmol/g and 10.8 mmol/g of benzene and hydrogen, respectively. Also, these adsorbents showed high uptakes of CH4 (2.1 mmol/g at 20 °C and 760 mm Hg) and CO2 (6.0 mmol/g at 0 °C and 760 mm Hg). The GO/OMC composite nanostructures were characterized by nitrogen adsorption, scanning electron microscopy, Raman spectroscopy and thermogravimetry. To the best of our knowledge, this work represents the first comparative study of adsorption properties of the GO/OMC composite nanostructures toward various gases.

Photovoltaic performance and impedance spectroscopy of ZnS-Cu-Go nanocomposites

In this work, novel, non-toxic and cost effective ZnS-Cu-GO nanocomposite is synthesized via wet chemical route to study its photovoltaic properties. Three samples including ZnS,ZnS-Cu and ZnS-Cu-GO were prepared and deposited as sensitizers on ZnO coated FTO substrates to assemble PV devices.The samples were characterized using UV–Vis NIR spectroscopy, Atomic force microscopy (AFM).Electrochemical impedance spectroscopy (EIS) and AM 1.5 Sun Simulator. It was observed that ZnS-Cu-GO exhibitedsuperiorchargetransport, remarkably high open circuit voltage(0.8V) and Fill factor (0.806).The current density significantly enhanced and maximum solar cell efficiency was observed for ZnS-Cu-GO based PV device. A pronounced red shift of 360nm in the absorption spectra was observed in the ZnS-Cu-GO due to fine dispersion of GO sheets.The AFM analysis showed that incorporation of GO and Cu maximized grain density and trench like grain boundaries in ZnS-Cu-GO which facilitated charge transport mechanism.A detailed electrochemical impedance study to probe charge dynamics in the prepared PV devices is presented herein.

Preparation of conductive carbon films from polyacrylonitrile/graphene oxide composite films by thermal treatment

Electrically-conductive carbon films were prepared by the thermal treatment of polyacrylonitrile/graphene oxide (PAN/GO) composite films. PAN/GO composite films spin-coated on substrates were stabilized in air and then carbonized under inert atmosphere at 1000°C to form carbon films. It was found that the cyclization of PAN and the partial reduction of GO occurred simultaneously during stabilization. The incorporation of GO was found to help to lower the energy and temperature of cyclization by an additional ionic reaction mechanism and to form large and compact crystalline structures. The electrical conductivity increased to 5.92×102S/cm with an increasing GO content.

Solvothermal Preparation of Microspherical Flowerlike Ni(OH)2/Graphene Oxide Electrode for Electrochemical Capacitor Application

The growing need for energy coupled with the rise in global warming and air pollution due to the burning and consumption of fossil fuels has led to an increase in alternative energy sources to meet the exponential rise in energy. Electrochemical capacitors also known as supercapacitors have attracted great attention in electrochemical energy storage application resulting from their outstanding work rate, excellent cycle life and moderate energy density. In general, they are classified into two based on the mechanism in which the store charges. Electrochemical double-layer capacitors (EDLCs) that store energy based on ion adsorption, and pseudocapacitors which store energy by the fast surface redox process. Composite of spherical Ni(OH)2/GO was synthesized via a surfactant free solvothermal technique and tested as electrodes for electrochemical capacitors. Structural and morphological analysis confirmed that incorporation of GO into Ni(OH)2 does not change the crystal structure of the pure hexagonal α-Ni(OH)2. Electrodes fabricated from the composite demonstrates a superior electrochemical performance by exhibiting a specific capacity of ∼ 420 mA h g-1 at 10 A g-1, with a corresponding rate capability of 78% when compared to that of pure Ni(OH)2, GO, and Mix-Ni(OH)2/GO. The stability study of the Ni(OH)2/GO composite exhibits a good capacity retention of ∼ 96% at a current density of 10 A g-1 after 3000 charge-discharge cycles. Figure 1

Facile fabrication of poly(ε-caprolactone)/graphene oxide membranes for bioreactors in tissue engineering

Promising polymer membranes of blended biocompatible poly(ε-caprolactone) and graphene oxide (PCL/GO) and PCL and partially reduced graphene oxide (PCL/rGO) with outstanding water and nutrient transport properties for cell culture bioreactors were prepared using phase inversion at mild temperatures. Some of the prepared PCL/GO membranes were subjected to a ‘chemical-free’ GO post-reductive process using UV (PCL/GO/UV) irradiation. The PCL/rGO membranes exhibited 2.5 times higher flux than previously reported biocompatible polymer membranes for cell culture bioreactors, which was attributed to the highly interconnected porosity. On the other hand, the formation of PCL-graphene oxide composites in the PCL/GO and PCL/GO/UV membranes was not conclusive according to spectroscopic analyses, thermal analyses and mechanical characterization, probably due to the low graphene oxide loading in the membranes (0.1%w/w). The presence of graphene oxide-based nanomaterials in the polymer matrix slightly reduced the mechanical properties of the PCL-graphene oxide membranes by limiting the polymer chain mobility in comparison to that of the plain PCL membranes. However, their mechanical stability was sufficient for the applications pursued. Finally, the biocompatibility assay indicated that the incorporation of GO and rGO into the PCL matrix enhanced the uniform distribution and morphology of the glioblastoma cells on the surface of the PCL-graphene oxide membranes.

Graphene oxide incorporated poly(ε-caprolactone) honeycomb-patterned porous polymer films by the breath figure method

Poly(e-caprolactone)-graphene oxide (PCL-GO) honeycomb-patterned films were successfully fabricated by breath figure method for the first time by the simple blending of individual components in a water miscible solvent, tetrahydrofuran. PCL-GO films were reduced using sodium borohydride to obtain PCL-reduced graphene oxide (PCL-rGO) films. The films were characterized by their color, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). TGA result shows the improvement of the thermal properties of PCL by the incorporation of GO. The SEM image shows the formation of monodispersed porous honeycomb-patterned PCL-GO films, and these patterns are retained after the reduction of GO to PCL-rGO without any wreckage. The reduction of GO to rGO was confirmed from the color of the films and from the XPS analysis. The present methodology is expected to widen the use of breath figure technique to achieve a wide variety of functionalized films by simple blending using water miscible solvents, which would otherwise not be possible using water immiscible solvents.

Enhanced mechanical, thermal and antimicrobial properties of poly(vinyl alcohol)/graphene oxide/starch/silver nanocomposites films

In the present work, synthesis of poly(vinyl alcohol)/graphene oxide/starch/silver (PVA/GO/Starch/Ag) nanocomposites films is reported. Such films have been characterized and investigated for their mechanical, thermal and antimicrobial properties. The exfoliation of GO in the PVA matrix occurs owing to the non-covalent interactions of the polymer chains of PVA and hydrophilic surface of the GO layers. Presence of GO in PVA and PVA/starch blends were found to enhance the tensile strength of the nanocomposites system. It was found that the thermal stability of PVA as well as PVA/starch blend systems increased by the incorporation of GO where strong physical bonding between GO layers and PVA/starch blends is assumed to cause thermal barrier effects. Antimicrobial properties of the prepared films were investigated against Escherichia coli and Staphylococcus aureus. Our results show enhanced antimicrobial properties of the prepared films where PVA-GO, PVA-Ag, PVA-GO-Ag and PVA-GO-Ag-Starch showed antimicrobial activity in ascending order.

Graphene oxide decorated electrospun gelatin nanofibers: Fabrication, properties and applications

Gelatin nanofiber fabricated by electrospinning process is found to mimic the complex structural and functional properties of natural extracellular matrix for tissue regeneration. In order to improve the physico-chemical and biological properties of the nanofibers, graphene oxide is incorporated in the gelatin to form graphene oxide decorated gelatin nanofibers. The current research effort is focussed on the fabrication and evaluation of physico-chemical and biological properties of graphene oxide-gelatin composite nanofibers. The presence of graphene oxide in the nanofibers was established by transmission electron microscopy (TEM). We report the effect of incorporation of graphene oxide on the mechanical, thermal and biological performance of the gelatin nanofibers. The tensile strength of gelatin nanofibers was increased from 8.29±0.53MPa to 21±2.03MPa after the incorporation of GO. In order to improve the water resistance of nanofibers, natural based cross-linking agent, namely, dextran aldehyde was employed. The cross-linked composite nanofibers showed further increase in the tensile strength up to 56.4±2.03MPa. Graphene oxide incorporated gelatin nanofibers are evaluated for bacterial activity against gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria and cyto compatibility using mouse fibroblast cells (L-929 cells). The results indicate that the graphene oxide incorporated gelatin nanofibers do not prevent bacterial growth, nevertheless support the L-929 cell adhesion and proliferation.

Preparation of Nafion/Pt-containing TiO2/graphene oxide composite membranes for self-humidifying proton exchange membrane fuel cell

Pt nanoparticles with about 2nm are successfully deposited onto ~50nm commercial TiO2 and various Nafion/xPt–TiO2/(1−x)Graphene oxide composite membranes are prepared. Water uptake of composite membrane is enhanced with GO content by maximum 15.3% due to hydrophilic GO compared to casting Nafion. Ion exchange capacity and proton conductivity are also enhanced with GO content but too much GO incorporation seems to reduce them probably due to the blocking effect by 2-dimensional GO sheets. Hydrophilic TiO2 alone does not seem to exhibit sufficient water retention ability to exert excellent cell performance. The results clearly show that the cell performance under low humidifying condition including zero humidity is significantly affected by retention ability of water formed from Pt sites. Thermogravimetric analysis shows that free water retained by membrane could be increased by 32% with the addition of TiO2 and 45% further with additional GO compared with that of casting Nafion, respectively. The cell performance is significantly enhanced by sinergistic effect upon addition of appropriate amount of Pt–TiO2 and GO to Nafion: that is, at 0.6V, 1.0A/cm2 and 0.54A/cm2 for Nafion/0.8Pt–TiO2/0.2GO, and 0.42A/cm2 and 0.02A/cm2 for casting Nafion under 100% RH and 0% RH.

Graphene oxide-polyaniline nanocomposites for high performance supercapacitor and their optical, electrical and electrochemical properties

Polyaniline/Graphene oxide (PA/GO) composites were prepared by chemical polymerization of aniline with different wt% of GO under acid conditions. The synthesized samples were characterized by using Fourier transform infra red spectroscopy, ultraviolet–visible absorption, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis. It is found that the dc electrical conductivity dramatically increased to 84 S/m for PA/GO (5 wt%) composite at 150 °C compared to pure PA (0.075 S/m). The PA/GO composites showed a reversible electrochemical response up to 150th repeated cycles as revealed by the cyclic voltammetry study. High specific capacitance of PA/GO composite of 543.75 F/g was obtained in the potential range from 0 to 0.50 V at 2 mA compared with 266.66 F/g for pure PA by galvanostatic charge–discharge analysis. Incorporation of GO into the polymer matrix has a pronounced effect on the electrical conductivity and electrochemical capacitance performance of PA/GO nanocomposites.

The Influence of Irradiation and Accelerated Aging on the Mechanical and Tribological Properties of the Graphene Oxide/Ultra-High-Molecular-Weight Polyethylene Nanocomposites

Graphene oxide/ultra-high-molecular-weight polyethylene (GO/UHMWPE) nanocomposite is a potential and promising candidate for artificial joint applications. However, after irradiation and accelerated aging, the mechanical and tribological behaviors of the nanocomposites are still unclear and require further investigation. GO/UHMWPE nanocomposites were successfully fabricated using ultrasonication dispersion, ball-milling, and hot-pressing process. Then, the nanocomposites were irradiated by gamma ray at doses of 100 kGy. Finally, GO/UHMWPE nanocomposites underwent accelerated aging at 80°C for 21 days in air. The mechanical and tribological properties of GO/UHMWPE nanocomposites have been evaluated after irradiation and accelerated aging. The results indicated that the incorporation of GO could enhance the mechanical, wear, and antiscratch properties of UHMWPE. After irradiation, these properties could be further enhanced, compared to unirradiated ones. After accelerated aging, however, these properties have been significantly reduced when compared to unirradiated ones. Moreover, GO and irradiation can synergistically enhance these properties.

Ambient Air and Hole Transport Layer Free Synthesis: Towards Low Cost CH3NH3PbI3Solar Cells

Perovskite absorbers have witnessed a remarkable efficiency increase in last couple of years. To meet the commercialization challenge, reduced cost and improved efficiency are the two critical factors. We report on a hole transport layer free device synthesized under ambient air conditions of high humidity of 50% using TiO2-graphene oxide nanocomposite as electron selective contact. The devices achieved a power conversion efficiency of 5.9%. We introduce a novel synthesis route for TiO2-graphene oxide (GO) composite allowing superior charge transport properties. Incorporation of GO in TiO2allows achieving higher power conversion efficiencies while working under ambient air conditions. Ambient air synthesis with hole transport free architecture has the potential to reduce the cost of this technology leading to commercial viability.