Functionalization Of Graphene Oxide Sheets Research Articles

Simultaneous reduction and functionalization of graphene oxide sheets with tannic acid for a strong composite material with multi-modally interactive interfaces

A multi-modally interactive interface is investigated to develop a strong structural material based on hybridization of graphene oxide (GO) and tannic acid (TA) through cross-linking with coordination and covalent bonds. GO is reduced and functionalized with TA by a simple wet-chemical reaction. The resulting TA-reduced and functionalized GO (TA-RGO) sheets are macroscopically assembled into lamellar structured paper like artificial nacre by vacuum-assisted filtration. The assembled TA-RGO paper is sequentially cross-linked by Fe3+ ion and polyethyleneimine (PEI) to form a strong interface through multimodal interactions such as hydrogen bonding, covalent bonding, coordination and π-π interactions. The suspended, assembled and cross-linked TA-RGO sheets are systematically characterized by various analytical tools. By forming the multimodal interactions, the tensile strength, modulus and toughness of GO paper were enhanced from 59.5 ± 4.1 MPa, 7.8 ± 1.4 GPa, and 765 ± 112 kJ/m3 to 167.7 ± 15.4 MPa, 17.6 ± 0.4 GPa, and 1484 ± 192 kJ/m3, respectively. Based on the results, we clearly demonstrated TA can be harnessed as a multifunctional agent for reducing, functionalizing and cross-linking RGO sheets to construct a strong structural material by forming multi-modally interactive interfaces.

Functionalization of graphene oxide sheets with magnetite nanoparticles for the adsorption of copper ions and investigation of its potential catalytic activity toward the homocoupling of alkynes under green conditions

This paper deals with the preparation of graphene oxide sheets (GO) modified with magnetite nanoparticles (Fe3O4NPs) for removing Cu(II) ions from aqueous solutions. Moreover, the recovered Cu(II)-based material was recycled as a catalyst for the homocoupling of a series of alkynes. The adsorption behavior of magnetic GO-based materials towards Cu(II) ions from aqueous solutions was studied as a function of the pH value and the contact time and it was observed that the magnetic GO-based absorbent can be separated quickly from its aqueous solution by using an external magnetic field. Its equilibrium adsorption capacity value for Cu(II) ions was as high as 3.808 ± 0.125 mmol.g−1 under neutral conditions. In addition, the catalytic activity of the resulting [GO-EDA-CAC@Fe3O4NPs]-BPED-Cu(II) material toward the homocoupling of phenylacetylene into 1,4-diphenylbuta-1,3-diyne was demonstrated with a yield up to 99%. Importantly, the [GO-EDA-CAC@Fe3O4NPs]-BPED-Cu(II) supported catalyst was consecutively reused for fifteen runs without a significant loss of its activity.

In-situ functionalization of GO sheets with AlOOH-FeOOH composite nanorods: An eco-friendly nanoadsorbent for removal of toxic arsenate ions from water

Water contaminated with arsenic (As) has become a worldwide problem due to its obligatory toxicity. Therefore, there is a great challenge for researchers to develop a cost-effective and highly efficient nanoadsorbent material for As removal. In this work, we have synthesized boehmite-lepidocrocite (AlOOH-FeOOH) composite nanorods mounted onto previously prepared graphene oxide (GO) surface (GO/AlOOH-FeOOH) by one step hydrothermal method. Then the prepared GO/AlOOH-FeOOH nanocomposite was sintered at 400 °C to form GO/Al2O3-Fe2O3 nanocomposite. Both the obtained GO functionalized nanocomposites were used as adsorbents for As(V) removal from water. The XRD, HRTEM confirmed the formation of γ (AlOOH-FeOOH) and γ (Al2O3-Fe2O3). TEM images revealed the formation of rod shape composite nanomaterials on GO surface. The GO/Al2O3-Fe2O3 showed magnetic properties with saturation magnetization value of 5.8emug−1. Among the two prepared nanoadsorbents the GO/AlOOH-FeOOH shows better adsorption properties with maximum uptake capacity of 24.6 mgg-1. The kinetics and isotherm experiments suggested that the adsorption process obeyed pseudo second order kinetic and Freundlich isotherm model. The presence of common coexisting anions including Cl-, SO42-, NO3- showed no significant effect on adsorption except PO43-. The mechanism of As(V) adsorption on GO/AlOOH-FeOOH includes electrostatic interaction and surface complexation reaction.

Bioconjugated graphene oxide hydrogel as an effective adsorbent for cationic dyes removal

In this study, graphene oxide - cellulose nanowhiskers nanocomposite hydrogel was easily synthesized through covalent functionalization of cellulose nanowhiskers with graphene oxide via a facile approach. The nitrene chemistry applied for covalent functionalization of graphene oxide sheets. The surface morphology and chemical structure of the nanocomposite hydrogel were characterized by FTIR, TGA, Raman, XRD, elemental analysis and SEM. The UV/Visible absorption spectrum revealed that the obtained porous nanocomposite hydrogel can efficiently remove cationic dyes such as methylene blue (MB) and Rhodamine B (RhB) from wastewater with high absorption power. The adsorption process showed that 100% of MB and 90% of RhB have been removed and the equilibrium state has been reached in 15min for low concentration solutions in accordance with the pseudo-second-order model. Moreover, the sample exhibited stable performance after being used several times. High adsorption capacity and easy recovery are the efficient factors making these materials as good adsorbent for water pollutants and wastewater treatment.

Epoxy/p‐phenylenediamine functionalized graphene oxide composites and evaluation of their fracture toughness and tensile properties

ABSTRACTIn an attempt to enhance the mechanical properties of epoxy/graphene‐based composites, the interface was engineered through the functionalization of graphene oxide (GO) sheets with p‐phenylenediamine; this resulted in p‐phenylenediamine functionalized graphene oxide (GO–pPDA). The morphology and chemical structure of the GO–pPDA sheets were studied by spectroscopic methods, thermal analysis, X‐ray diffraction, and transmission electron microscopy. The characterization results show the successful covalent functionalization of GO sheets through the formation of amide bonds. In addition, p‐phenylenediamine were polymerized on graphene sheets to form crystalline nanospheres; this resulted in a GO/poly(p‐phenylenediamine) hybrid. The mechanical properties of the epoxy/GO–pPDA composite were assessed. Although the Young's modulus showed improvement, more significant improvements were observed in the strength, fracture strain, and plane‐strain fracture toughness. These improvements were attributed to the unique microstructure and strong interface between GO–pPDA and the epoxy matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43821.

Tunable Functionalization of Graphene Oxide Sheets through Surface-Initiated Cationic Polymerization

Surface functionalization of graphene oxide (GO) sheets using polymers has emerged as a subject of enormous scientific interest due to the wide applications of GO in polymer composites and functional graphene-based materials. In this study, we grafted GO sheets with polystyrene (PS) and poly(styrene–isoprene) (PSI) using GO itself as a cationic initiator for homopolymerization of styrene and copolymerization of styrene and isoprene. The resultant GO-g-PS and GO-g-PSI composites displayed enhanced dispersibility in common organic solvents. With increasing the loading of isoprene in the copolymerization reaction, the glass transition temperature of the obtained products gradually decreased, combining the increased roughness of the GO-g-PSI sheets compared with the GO-g-PS sheets, which indicated the increased phase separation between the PS and PI segments in the PSI layer. Therefore, the packing of the GO-g-PS sheets, as well as the GO-g-PSI sheets, was not as compact as that of the GO sheets, leaving grad...

Self-assembly of thiolated graphene oxide onto a gold surface and in the supramolecular order of discotic liquid crystals

Covalent functionalization of graphene oxide sheets with thiol produces thiolated graphene oxide which self assembles on gold surfaces and in the supramolecular structure of a discotic mesophase which have potential applications in optoelectronics.

Graphene oxide-based electrochemical sensor: a platform for ultrasensitive detection of heavy metal ions

Facile functionalization of graphene oxide sheets on gold surface results in complexation-enhanced electrochemical detection of heavy metal ions, shown here for Pb2+, Cu2+ and Hg2+, with improved detection limits by two orders of magnitude relative to the control electrode.

Reduction and Functionalization of Graphene Oxide Sheets Using Biomimetic Dopamine Derivatives in One Step

An easy and environmentally friendly chemical method for the simultaneous reduction and noncovalent functionalization of graphene oxide (GO) using dopamine derivatives is described. The reaction takes place at room temperature under ultrasonication of an aqueous suspension of GO and a dopamine derivative. X-ray photoelectron spectroscopy, FT-IR spectroscopy, and cyclic voltammetry characterizations revealed that the resulting material consists of graphene functionalized with the dopamine derivative. This one-step protocol is applied for simultaneous reduction and functionalization of graphene oxide with a dopamine derivative bearing an azide function. The chemical reactivity of the azide function was demonstrated by a postfunctionalization with ethynylferrocene using the Cu(I) catalyzed 1,3-dipolar cyloaddition.

Protein-directed reduction of graphene oxide and intracellular imaging

We demonstrate a facile, one-step, protein-directed approach to preparing a new functional reduced graphene oxide via simultaneous reduction and surface functionalization of graphene oxide sheets with herceptin and show its potential application as a novel biological imaging agent.