Chemical Modification Of Graphene Oxide Research Articles

Functionalization of graphene oxide as a way to increase biocompatibility

Introduction. Now, one of the most promising areas for the use of graphene-based materials, in particular graphene oxide, is biomedicine. Due to the wide variety of functional groups and the possibility of chemical modification of graphene oxide, the creation of composite materials for biomedical use is promising. These nanomaterials have a unique structure and properties, which determines their use for creating targeted drug delivery systems, in tissue engineering, bioimaging, as well as for creating new materials with antimicrobial and antiviral properties.The objective was to perform synthesis and identification of graphene oxide and its conjugate with glycine, and to study the biocompatibility of the obtained nanomaterials: the effect on haemolysis and platelet aggregation, genotoxicity and cytotoxicity.Methods and materials. Graphene oxide was synthesized from graphite using the modified Hummers and Offeman method, after which the graphene oxide-glycine conjugate was also obtained. Identification was carried out using nuclear magnetic resonance spectroscopy. Estimation of biocompatibility of the obtained nanomaterials included the study of their hemolytic activity, effect on collagen-induced platelet aggregation, cyto- and genotoxicity.Results. Graphene oxide and its conjugate with glycine were synthesized. Identification with using nuclear magnetic resonance spectroscopy confirmed the structure and composition of the substances. The study of the biocompatibility of the obtained nanomaterials showed the absence of hemolytic activity (the degree of hemolysis did not exceed 2.5% at the studied concentration range); the presence of antiplatelet properties (at C=10–100 mg·ml–1); the absence of geno- and cytotoxicity (graphene oxide at C=0.25–25 mg·L–1 does not affect the viability of HEK293 cells; in turn, the conjugate with glycine at C=100–200 mg·L–1 causes a dose-dependent increase proliferation of HEK293 cells).Conclusion. The study demonstrates that functionalization of the graphene surface with oxygen-containing groups and amino acids leads to increased hemocompatibility, as well as to the production of nanomaterials that do not exhibit genoand cytotoxicity.

Facile strategy for the preparation of green graphene rubber with enhanced interfacial interaction and thermal management capability

AbstractThe development of high‐performance green rubber materials with excellent comprehensive properties is very important for the environment and resources. Graphene has excellent electrical, mechanical, and thermal properties and is regarded as the most promising functional filler for rubber composites. In this work, a facile and efficient strategy was used to prepare graphene rubber materials with balanced integrated properties by chemical modification of graphene oxide (GO) with gelatin (Gel). Gel molecules as bridges could not only connect with GO by chemical bonds, but also physically entangle with natural rubber (NR) molecules. The optimized dispersibility of GO and the enhanced interfacial interaction between GO and NR together enable graphene rubber to exhibit excellent integrated properties, such as tensile strength of 29.7 MPa and heat build‐up of 1.9°C only at 1 phr of Gel‐rGO (G‐rGO) content. Additionally, finite element simulation was used to evaluate the temperature field distribution of graphene rubber tires, and the temperature of the NR/Gel‐rGO (NR/G‐rGO) tread was 17.3°C lower than that of NR/GO. This work will provide effective strategies for the preparation of high‐performance graphene rubber materials.

Molecular Dynamics study of the effect on the interfacial activity of Alkylamine-Modified graphene oxide

Several experimental studies have shown that chemical modification of graphene oxide with n-alkylamines allow to control its interfacial activity in oil–water systems, altering its dispersibility and favoring the formation of emulsions. However, due to the complexity of its chemical structure and experimental limitations, the emulsification mechanism and interfacial properties have not been fully understood. In order to understand the behavior at the oil-water interface of alkylamine functionalized Graphene Oxide (GO) based materials, in this research we evaluated the interfacial activity of GO functionalized with different alkylamines (aGO) with different aliphatic chain lengths of 1, 3, 5, 7, 9 and 12 carbon atoms by Molecular Dynamics simulations. The dispersibility of the GO-based materials was analyzed and it was found that the Hydrophilic-Lipophilic Balance (HLB) of the GO can be controlled with the alkylamine chain length, making the GO more hydrophobic as the aliphatic chain length of the alkylamines becomes longer. Alkylamine chains bonded on the GO structure were capable to modifying the orientation relative to the Toluene/Water interface, going from parallel for the GO case to orthogonal for the aGO nanosheets, adopting a “head–tail” configuration due to the hydrophobic effect between the aliphatic chains and the Water molecules. Simulations also revealed that synergistic effect of aGO can decrease the interfacial tension of the Toluene-Water system as the aliphatic chain length and number of sheets increase obeying the Traubés rule, indicating a behavior like molecular surfactant, where the IFT of the system decreases as the amount of surfactant increases.

Study of the water-oil interfacial activity of amino-modified graphene oxide

The interfacial properties of Graphene oxide (GO) based materials have been widely studied in emulsification processes. The 2D chemical structure and high reactivity of Graphene Oxide (GO) allows the properties modification as wettability and dispersibility. Furthermore, the functionalized GO has been tested as a surfactant agent; however, little or nothing is known about its mechanism of action. Here, we investigated the interfacial activity of amine-modified GO in a water-toluene system. To consider the effect of the aliphatic chain length, GO was functionalized by amidation reaction and nucleophilic substitutions with n-propylamine (GO@3 C) and n-dodecylamine (GO@12 C). The covalent functionalization of GO was confirmed by FTIR spectroscopy, Raman spectroscopy, XPS spectroscopy, XRD and their morphology were observed by Scanning Electron microscopy. Results showed that the chemical modification of GO with n-alkylamines can decrease the Interfacial Tension (IFT) of the water-toluene system as the nanomaterial concentration increase, like a molecular surfactant that obey the Traube´s rule. Wettability of the materials it was also determined by the sessile drop method, revealing that the GO hydrophobicity increases as the length of the aliphatic chain becomes longer. Characteristics of the emulsion droplets were determined by micrograph analysis, and it was revealed that the diameter size, stability, and kind of emulsion can be changed depending on the type of GO functionalization.

Graphene Oxide Derivatives and Their Nanohybrid Structures for Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Analysis of Small Molecules.

Matrix-assisted laser desorption/ionization (MALDI) has been considered as one of the most powerful analytical tools for mass spectrometry (MS) analysis of large molecular weight compounds such as proteins, nucleic acids, and synthetic polymers thanks to its high sensitivity, high resolution, and compatibility with high-throughput analysis. Despite these advantages, MALDI cannot be applied to MS analysis of small molecular weight compounds (<500 Da) because of the matrix interference in low mass region. Therefore, numerous efforts have been devoted to solving this issue by using metal, semiconductor, and carbon nanomaterials for MALDI time-of-flight MS (MALDI-TOF-MS) analysis instead of organic matrices. Among those nanomaterials, graphene oxide (GO) is of particular interest considering its unique and highly tunable chemical structures composed of the segregated sp2 carbon domains surrounded by sp3 carbon matrix. Chemical modification of GO can precisely tune its physicochemical properties, and it can be readily incorporated with other functional nanomaterials. In this review, the advances of GO derivatives and their nanohybrid structures as alternatives to organic matrices are summarized to demonstrate their potential and practical aspect for MALDI-TOF-MS analysis of small molecules.

Reduction of graphene oxide and graphene quantum dots using nascent hydrogen: The investigation of morphological and structural changes

AbstractIn order to modify both chemical and electrical properties of graphene-based nanomaterials, we conducted the chemical modification of graphene oxide (GO) and graphene quantum dots (GQDs). The reaction of the reduction with nascent hydrogen was conducted on both materials. The structure and morphology of produced chemically reduced GO and GQDs were analyzed. While the chemical composition of both GQD and GO changed significantly, GO showed also significant changes in morphology as opposite to GQDs where were morphological changes were not observed.

Facilitated transport membranes containing graphene oxide-based nanoplatelets for CO2 separation: Effect of 2D filler properties

Realization of suitable membrane-based technology for efficient CO2 capture to mitigate climate change relies on the development of thin-film composite (TFC) membranes with superior separation performance. Graphene oxide (GO), due to its 2D morphology, intrinsic strength and chemical compatibility, was used as a nanofiller to enhance CO2 separation performance and stability of a facilitated transport membrane. SHPAA (sterically hindered polyallylamine)-based blend matrix was selected as the polymeric matrix material in this work. The high aspect ratio of GO-based fillers, when coupled with optimized coating protocol, resulted in TFC membranes of ultrathin (200 nm) selective layers with the in-plane orientation of nanoplatelets, leading to enhanced separation properties that can be retained for long term. Porous graphene oxide (pGO) was also incorporated as nanofillers, resulting in significantly improved gas permeation at a very low filler loading of 0.2 wt%; A CO2 permeance of up to 607 GPU with a CO2/N2 separation factor of 36 in flat-sheet configuration was documented. Chemical modification of GO with PEG groups was found to further increase the selectivity of the membranes but reduces the CO2 permeance, showing a CO2/N2 separation factor of 90 with a CO2 permeance of 205 GPU. The effect of various 2D nanoplatelets on CO2 transport properties in the membranes of hydrophilic PVA (polyvinyl alcohol) matrix and facilitated transport SHPAA/PVA matrix was elucidated with respect to the nanofiller property and loading.

Facile modification of graphene oxide and its application for the aqueous uranyl ion sequestration: Insights on the mechanism

Graphene oxide (GO) has been proved with favorable affinity to U(VI), while some drawbacks such as poor dispersity and low adsorption performance limit its application. Herein, cetyltrimethylammonium bromide (CTAB) modified graphene oxide (MGO) composites were successfully fabricated, characterized and compared with graphene oxide (GO) in the sequestration of U(VI) in aqueous solutions. The results showed that maximum adsorption rate of MGO (99.21%) was obviously higher than that of GO (66.51%) under the same initial condition. Simultaneous introduction of C–H and NO coupled with the enhanced dispersity of GO after modification were mainly responsible for the updated performance verified with multiple characterization techniques. Based on the results of kinetics and isotherms investigations, the experimental data were best described by Pseudo-first-order kinetic model and Redlich-Peterson isotherm model. The results of ΔH, ΔS and ΔG show that adsorptive behaviors of uranyl ion on MGO are endothermic and spontaneous. The study provides a feasible alternative to the chemical modification of GO and enhancing the performance towards uranyl ion removal from solution.

Chemical modification of graphene oxide to reinforce the corrosion protection performance of UV-curable polyurethane acrylate coating

An eco-friendly polyurethane acrylate (PUA) /functionalized graphene oxide nanocomposite coating with excellent corrosion resistance was prepared by UV curing technology. Graphene oxide (GO) was covalently modified by the reactive PUA molecules to improve its dispersibility and the interaction with the polymer matrix, which was verified by the results obtained from Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Subsequently, the PUA functionalized GO (denoted as PGO) nanosheets were doped into the PUA resin matrix. The structures and morphologies of the blank PUA coating, the PUA/GO nanocomposite coating and the PUA/PGO nanocomposite coating were characterized by field emission scanning electron microscope (FESEM), and their corrosion resistance was investigated via electrochemical impedance spectroscopy (EIS) and salt spray test. Results revealed that the incorporation of PGO nanosheets remarkably improved the corrosion resistance of the PUA matrix due to their good dispersion, outstanding barrier properties and strong bonding strength with the polymer matrix.

Morphological, mechanical and thermal properties of PA6 nanocomposites Co-Incorporated with Nano-Al2O3 and graphene oxide fillers

In this paper, the surface hydroxylation modification of nano-alumina (nano-Al2O3) to result nano-Al2O3–OH and the chemical modification of graphene oxide (GO) by using silane coupling agent to produce GO-KH560 were first carried out respectively, followed by solution compounding to synthesis a novel three-dimensional functional hybrid filler (nano-Al2O3–OH/GO-KH560), and then polyamide 6 (PA6)/nano-Al2O3–OH/GO-KH560 (abbreviated as P-A-OH-G-KH560) thermally conductive nanocomposites were fabricated by melt blending technique and investigated for its morphological, mechanical and thermal properties. Morphological characterization revealed better dispersion of nano-Al2O3 and GO in the PA6 nanocomposites, which is attributed to the improved interfacial interaction between the PA6 and hybrid fillers. Loading of the hybrid fillers in the PA6 nanocomposites resulted in the significant improvement in mechanical properties such as tensile strength and elastic modulus and this effect is more pronounced on the increasing the hybrid fillers loading amount, when compared to the PA6 and pristine nano-Al2O3 filled system. Differential scanning calorimetric analysis showed that the crystallization of the PA6 nanocomposites was improved. The thermal conductivity of the P-A-OH-G-KH560 (100/5/0.8) nanocomposite increased by 86.13% compared with that of pure PA6. In summary, PA6 nanocomposites with fairly good mechanical and thermal conductivity are obtained at low filler contents.

A Schiff base modified graphene oxide film for anodic stripping voltammetric determination of arsenite.

A protocol is described for chemical modification of graphene oxide with a Schiff base derived from diethylenetriamine and 2-hydroxy-4-methoxybenzophenone. The base was grafted onto an indium tin oxide (ITO) film and applied to electroanalytical determination of arsenite. Successful grafting was confirmed by Fourier transform-infrared spectroscopy, spectrophotometry, field emission scanning electron microscopy and cyclic voltammetry. Secondly, the coated ITO film served as a working electrode for the stripping voltammetric determination of arsenite. The analytical signal is generated by selective oxidation of metal species via multi-donor sites present in the derivatized Schiff base. The electroanalytical protocol was optimized by investigating the effects of deposition time, working potential, frequency and amplitude of square wave anodic stripping voltammetry. The method has attractive features including (a) the usage of a non-metallic, non-toxic and cost-effective material; (b) improved sensitivity (with limit of detection as low as 156 pM) due to better adsorption of arsenite in the Schiff base pockets on the ITO, and (c) the application to the determination of arsenite in real samples. Graphical abstract Schematic representation of the fabrication of a Schiff base-functionalized graphene oxide on an indium tin oxide (SB@SiO2@GO@ITO) electrode for selective electrochemical sensing of arsenite due to adsorption on multi-donor sites.

Visualization analysis of graphene and its composites for heavy metal wastewater applications.

In order to explore the research trends and hotspots related to the treatment of heavy metals in wastewater by graphene and its composites, this study collected information on 511 publications from the Science Citation Index-Expanded (SCIE) and conducted a quantitative and visual analysis. The article on the adsorption of heavy metals in wastewater by graphene and its composites first appeared in 2006 and continued to grow since 2011. It broke through 100 articles for the first time in 2016 and the overall trend is on the rise. The 511 articles were published in 185 journals, of which RSC Advances is the most dynamic journal, and Journal of Materials Chemistry A is the most authoritative journal. Asian authors published about 87.14% of papers, and China, Iran, and India played a leading role compared with other countries. The University of Chinese Academy of Sciences is the largest research institution for the adsorption of heavy metals in wastewater by graphene and its composites. Hot keywords are "heavy metal removal," "water sample," "recent advance," "reusable adsorbent," "graphene-based material," and "composite nanosheet." Combined with keywords and cluster analysis, the chemical modification of graphene oxide has become a hot research direction for graphene materials to remove heavy metals from wastewater. Among them, MnFe2O4-graphene composite is a hot spot for graphene modification. In general, HNO3, HCl, and EDTA are desorption reagents for graphene and its composites.

PEGylated doxorubicin cloaked nano-graphene oxide for dual-responsive photochemical therapy

Graphene oxide (GO) owns huge surface area and high drug loading capacity for aromatic molecules, such as doxorubicin (DOX). However, its biocompatibility is poor and it might agglomerate in physiological conditions. Chemical modification of GO with hydrophilicpolymer, especially PEGylation, was a common method to improve its biocompatibility. But the chemical modification of GO was complicated, and its drug loading capacity might be reduced because of the occupation of its functional groups. In this study, DOX-PEG polymers with different PEG molecular weights were synthesized to modify nano graphene oxide (NGO) to simultaneously realize the solubilization of NGO and the high loading capacity of DOX. The result showed that the drug release of NGO@DOX-PEG was pH sensitive. NIR irradiation could augment the drug release, cellular uptake, cytotoxicity and nuclear translocation of nanodrugs. Among the three kinds of nanodrugs, NGO@DOX-PEG5K was superior to others. It suggested that after conjugating with PEG, the bond between DOX-PEG and NGO was weakened, which resulted in a better drug release and treatment effect. In summary, the NIR and pH dual-responsive NGO@DOX-PEG nanodrugs were developed by noncovalent modification, and it demonstrated excellent biocompatibility and photochemical therapeutic effect, presenting a promising candidate for antitumor therapy, especially NGO@DOX-PEG5K.

Assessment of the chitosan-functionalized graphene oxide as a carrier for loading thioguanine, an antitumor drug and effect of urea on adsorption process: Combination of DFT computational and molecular dynamics simulation studies

In this study, the interaction thioguanine (TG) anticancer drug with the functionalized graphene oxide (GO) nanosheet surface is theoretically studied in both gas phase and separately in physiological media using the density functional theory (DFT) calculations. DFT calculations indicated the adsorption and solvation energies are negative for f-GONS/TG complexes which propose the adsorption process of TG molecule onto the f-GONS surface is possible from the energetic viewpoint. QTAIM calculations confirm the nature of partially covalent-partially electrostatic between drug and nanosheet. These results are sorely relevant that an approach for loading of TG molecule is the chemical modification of GO using covalent functionalization which can serve as a nanocarrier to load drug molecules. Moreover, to understand the effect of urea on the nature of the interaction between TG and f-GONS, molecular dynamics (MD) simulation was employed. The results indicated that in the presence of urea the adsorption process gets affected and leads to instability of system, while the affinity of the TG for adsorption onto GO surface is increased in pure water.Communicated by Ramaswamy H. Sarma

Efficient Removal of Heavy Metals from Polluted Water with High Selectivity for Mercury(II) by 2-Imino-4-thiobiuret-Partially Reduced Graphene Oxide (IT-PRGO).

A novel chelating adsorbent, based on the chemical modification of graphene oxide by functionalization amidinothiourea to form 2-imino-4-thiobiuret-partially reduced graphene oxide (IT-PRGO), is used for the effective extraction of the toxic metal ions Hg(II), Cu(II), Pb(II), Cr(VI), and As(V) from wastewater. FTIR and Raman spectroscopy, XRD, and XPS confirm the successful incorporation of the amidinothiourea groups within the partially reduced GO nanosheets through nucleophilic substitution reactions with the acyl chloride groups in the chemically modified GO. The IT-PRGO adsorbent shows exceptional selectivity for the extraction of Hg(II) with a capacity of 624 mg/g, placing it among the top of carbon-based materials known for the high capacity of Hg(II) removal from aqueous solutions. The maximum sorption capacities for As(V), Cu(II), Cr(VI), and Pb(II) are 19.0, 37.0, 63.0, and 101.5 mg/g, respectively. The IT-PRGO displays a 100% removal of Hg(II) at concentrations up to 100 ppm with 90%, 95%, and 100% removal within 15, 30, and 90 min, respectively, at 50 ppm concentration. In a mixture of six heavy metal ions containing 10 ppm of each ion, the IT-PRGO shows a removal of 3% Zn(II), 4% Ni(II), 9% Cd(II), 21% Cu(II), 63% Pb(II), and 100% Hg(II). A monolayer adsorption behavior is suggested based on the excellent agreement of the experimental sorption isotherms with the Langmuir model. The sorption kinetics can be fitted well to a pseudo-second-order kinetic model which suggests a chemisorption mechanism via the amidinothiourea groups grafted on the reduced graphene oxide nanosheets. Desorption studies demonstrate that the IT-PRGO is easily regenerated with the desorption of the metal ions Hg(II), Cu(II), Pb(II), Cr(VI), and As(V) reaching 96%, 100%, 100%, 96%, and 100%, respectively, from their maximum sorption capacities using different eluents. The IT-PRGO is proposed as a top performing remediation adsorbent for the extraction of heavy metals from waste and polluted water.

Morphological, rheological, crystalline and mechanical properties of ethylene-vinyl acetate copolymer/linear low-density polyethylene/amphiphilic graphene oxide nanocomposites

Chemical modification of graphene oxide has become a popular method for imparting unique properties to extend its application. Here, we show a simple way to synthesize amphiphilic graphene oxide (AGO) by grafting quaternary ammonium salt onto GO sheets. The AGO sheets not only showed high thermal stability and good dispersion in many polar and non-polar solvents in comparison to GO sheets but also the chemical modification maintained the two-dimensional structure. As a result, the AGO sheets improve the interfacial interaction between ethylene-vinyl acetate copolymer (EVA) and linear low-density polyethylene (LLDPE). Because of the large size of AGO, the location of AGO is very dependent on the mixing strategy. The AGO was dispersed in the EVA phase when AGO was mixed first with EVA and then with LLDPE, whereas it was confined in the LLDPE phase when AGO was mixed first with LLDPE and then with EVA. AGO sheets were found at the interface of LLDPE and EVA when AGO, EVA, and LLDPE were mixed together, suggesting that AGO has a high interfacial interaction with both LLDPE and EVA. These high interfacial interactions lead to high tensile strength, Young's modulus, complex viscosity and crystallization temperature in comparison to the EVA/LLDPE blends without AGO sheets.

Chemical modification of graphene oxide through poly(ethylene oxide)-conjugations

This paper introduces poly(ethylene oxide) (PEO)-based modification of graphene oxide (GO) layers through the grafting onto the surface of GO as one of the excellent tools to improve the solubility and the processing ability of graphene. Methylene blue (MB)-mediated intercalation of graphite (flake) was first performed at 25 °C in aqueous media, followed by the Hummers’ process for oxidation, leading to an efficient production of GO. Direct oxidation of graphite (powder) also yielded the corresponding GO. The reaction of neutralized GO with “living” PEOs synthesized from alkyllithium- or sodium azide-initiated polymerization of ethylene oxide (EO) in polar solvents led to the production of the corresponding graphene oxide-g-PEOs soluble in different solvents such as tetrahydrofuran (THF), methanol, dimethyl sulfoxide (DMSO), and H2O, etc. The resulting products were characterized by the combination of size exclusion chromatographic, 1H nuclear magnetic resonance (1H NMR), Raman, thermogravimetric anlysis (TGA), transmission electron microscopy (TEM), and atomic force microscopy (AFM) analyses.

Antimicrobial proteins in the response to graphene oxide in Caenorhabditis elegans

Upon exposure to environmental engineered nanomaterials (ENMs), animals will activate certain response signals to protect themselves from the toxic effects. However, the underlying molecular mechanisms for this response are still largely unclear. Using in vivo assay system of Caenorhabditis elegans, we here found that antimicrobial proteins of LYS-1, LYS-8, SPP-1, DOD-6, and F55G11.4 were activated by graphene oxide (GO) exposure. These antimicrobial proteins functioned as molecular targets of transcriptional factor DAF-16 in insulin signaling pathway, and acted in intestine to regulate the response to GO. Among these antimicrobial proteins, DOD-6, F55G11.4, and SPP-1 participated in the formation of signaling cascade of DAF-16-DOD-6-SOD-3-F55G11.4/SPP-1 in response to GO exposure by activating the antioxidation system. Different from this, LYS-1 and LYS-8, two lysozymes, mediated TUB-2 signaling and DAF-8-DAF-5 signaling cascade, respectively, to regulate the response to GO exposure. During the regulation of response to GO exposure, LYS-1 and LYS-8 acted synergistically, which could be largely explained by the observed synergistic interaction between TUB-2 and DAF-8. Therefore, our results demonstrate the crucial protection role of antimicrobial proteins for animals in response to environmental ENMs’ exposure. The elucidated different signaling cascades mediated by antimicrobial proteins provide important molecular targets for future toxicity assessment and chemical modification of GO.

Chemical Modification of Graphene Oxide by Nitrogenation: An X-ray Absorption and Emission Spectroscopy Study

Nitrogen-doped graphene oxides (GO:Nx) were synthesized by a partial reduction of graphene oxide (GO) using urea [CO(NH2)2]. Their electronic/bonding structures were investigated using X-ray absorption near-edge structure (XANES), valence-band photoemission spectroscopy (VB-PES), X-ray emission spectroscopy (XES) and resonant inelastic X-ray scattering (RIXS). During GO:Nx synthesis, different nitrogen-bonding species, such as pyrrolic/graphitic-nitrogen, were formed by replacing of oxygen-containing functional groups. At lower N-content (2.7 at%), pyrrolic-N, owing to surface and subsurface diffusion of C, N and NH is deduced from various X-ray spectroscopies. In contrast, at higher N-content (5.0 at%) graphitic nitrogen was formed in which each N-atom trigonally bonds to three distinct sp2-hybridized carbons with substitution of the N-atoms for C atoms in the graphite layer. Upon nitrogen substitution, the total density of state close to Fermi level is increased to raise the valence-band maximum, as revealed by VB-PES spectra, indicating an electron donation from nitrogen, molecular bonding C/N/O coordination or/and lattice structure reorganization in GO:Nx. The well-ordered chemical environments induced by nitrogen dopant are revealed by XANES and RIXS measurements.

Fabrication of chemically modified graphene oxide/nano hydroxyapatite composite for adsorption and subsequent photocatalytic degradation of aureomycine hydrochloride

Chemically modified graphene oxide (CMGO)/nanohydroxy apatite (nHA) composite was synthesized via a facile chemical modification of graphene oxide (GO) by triethyltetramine (TETA). Band gap of GO could be tuned for photo degradation under visible light through surface modification as well as by the composite formation with nHA. Pseudo-second-order kinetic model related the drug adsorption while degradation process followed first-order kinetics with Sips isotherm as the best fitted model. Feasibility of photo catalyst in the degradation of AM was tested using waste water samples collected from polluted area near to poultry fields and animal farm houses.