Amino-functionalized Graphene Oxide Research Articles

Efficient synthesis of graphene oxide-supported molybdenum compounds exhibiting excellent peroxidase-like activity

Two novel compounds involving molybdenum supported by graphene oxide and functionalized with 3-aminopropyltriethoxysilane (APTES) were designed as [(MoO2·H2O)2(L1)]@APTES@GO 3 and [(MoO2·H2O)2(L2)]@APTES-GO 4. These complexes were synthesized by reacting amino-functionalized graphene oxide (APTES@GO) with [(MoO2·H2O)2(L1)] 1, [(MoO2·H2O)2(L2)] 2 in a 1:1 ratio in an ethanolic solution. The structural characterization of the supported compounds was conducted using multiple analytical techniques including Fourier-transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–vis), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HR-TEM), powder X-ray diffraction (PXRD), Brunauer–Emmett–Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS). The findings from these characterization methods collectively demonstrated the successful binding of the molybdenum complexes onto the surface of the functionalized graphene oxide. Furthermore, the catalytic performance of these supported compounds was assessed for their peroxidase-like action in the oxidation reactions of o-phenylenediamine (OPD) and 3,3′-diaminobenzidine (DAB). Recycling and reusability investigations indicated that the catalytic activity slightly changes over four consecutive catalytic cycles.

Amination modification of graphene oxide for the in-situ synthesis of sulfonated polyimide-based composite proton exchange membranes

To mitigate the severe degradation of mechanical properties and stability of highly sulfonated proton exchange membranes (PEMs) caused by the sulfonic acid groups, amino-functionalized graphene oxide (AGO) was embedded into sulfonated polyimide (SPI) for the in-situ synthesis of a composite proton exchange membrane. The introduction of AGO nanoparticles facilitated the enhancement of the crystallinity of the composite membrane, with the well-constructed interface and dispersion. The resulting AGO-SPI composite membrane exhibited high mechanical strength and stability. The fracture strength of AGO-SPI composite membrane was approximately 61 MPa, which was 1.85 times higher than that of pure SPI. Meanwhile, the weight loss of AGO-SPI composite membrane in Fenton’s reagent was only 2.11 %. Additionally, at 90 °C/98 % RH, the proton conductivity of AGO-SPI composite membrane reached 50.1 mS cm−1, which was 3.53 times higher than that of pristine SPI. The results suggest the promising application prospects of the proton exchange composite membrane.

Amino-functionalized graphene oxide affects bacteria–phage interactions in aquatic environments

The widespread use of graphene family nanomaterials (GFNs) in mass production has resulted in their release into the atmosphere, soil and water environment through various processes. Among these, the water environment is particularly affected by GFN pollution. Our previous study has demonstrated the impact of graphene oxide (GO) on bacteria–phage interactions in natural systems. However, the effects of amino-functionalized GO with a positive charge on bacteria–phage interactions in aquatic environments remain unclear. In the present study, we found that amino-functionalized graphene oxide (AGO) (0.05 mg/mL) inhibited the growth of Pseudomonas aeruginosa Y12. Furthermore, treating P. aeruginosa Y12 and phage with AGO (0.05 mg/mL) led to a reduced ratio of phage to bacteria, indicating that AGO can inhibit phage infection of bacteria. Additionally, the acidic environment exacerbated this effect by promoting electrostatic adsorption between the positively charged AGO and the negatively charged phage. Finally, a field water body intervention experiment showed that the richness and diversity of bacterial communities in six water samples changed due to AGO exposure, as revealed by Illumina analysis based on the bacterial 16S rRNA gene. These findings offer valuable insights into the environmental impacts of GFNs.

Formation and catalytic potential of sheet like nanostructured amino functionalized graphene oxide Schiff's base immobilized by Cu nanoparticles in Click reaction, oxidation of fluorene and in photodegradation of methylene blue

A heterogeneous catalyst, environmentally benign, containing copper immobilized over amino functionalized Schiff's base graphene oxide was prepared. The prepared nanocatalyst was explored in various organic transformations such as in tri-azoles formation, in oxidation and the degradation of methylene blue. Click chemistry was employed in the formation of triazoles for the construction of carbon-heteroatom bonds which have many applications ranging from drug discovery to material science. Our present work focused on graphene-based nanocatalyst (Cu @NH2GO) which provided excellent efficiency and catalytic activity in carrying out organic transformations. The prepared nanocatalyst was characterized and examined by various spectroscopic techniques such as X-ray diffraction (PXRD), thermo gravimetric analysis (TGA), field emission-scanning electron microscopy (FE-SEM), EDX, high-resolution transmission electron microscopy (HR-TEM), Fourier transformer infrared spectroscopy (FT-IR), and X-ray Photoelectron Spectroscopy (XPS). TEM images showed the light grey sheets of silane functionalized Schiff's base on which Cu nanoparticles were immobilized. The catalyst was also explored for the degradation of methylene blue which provided an effective path for the treatment of wastewater. Methylene Blue is one of the environmentally persistent, carcinogenic and mutagenic cationic dyes. A large volume of methylene blue containing wastewater is discharged into groundwater or surface water. So it becomes necessary to degrade the toxic dye by the use of a prepared nanocatalyst (Cu @NH2GO). Moreover, the catalyst possesses excellent stability and reusability.

Amino-Modified Graphene Oxide from Kish Graphite for Enhancing Corrosion Resistance of Waterborne Epoxy Coatings.

Waterborne epoxy (WEP) coatings with enhanced corrosion resistance were prepared using graphene oxide (GO) that was obtained from kish graphite, and amino-functionalized graphene oxide (AGO) was modified by 2-aminomalonamide. The structural characteristics of the GO and AGO were analyzed using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). And the anti-corrosive performance of waterborne epoxy-cased composite coatings with different addition amounts of AGO was investigated using electrochemical measurements, pull-off adhesion tests, and salt spray tests. The results indicate that AGO15/WEP with 0.15 wt.% of AGO has the best anti-corrosive performance, and the lowest frequency impedance modulus increased from 1.03 × 108 to 1.63 × 1010 ohm·cm-2 compared to that of WEP. Furthermore, AGO15/WEP also demonstrates the minimal corrosion products or bubbles in the salt spray test for 200 h, affirming its exceptional long-term corrosion protection capability.

Rheology of amino-functionalized graphene oxide suspensions in hydrogels

This work investigates the effects of amino-functionalized graphene oxide (AFGO) suspensions on the rheological behavior of Carbopol® hydrogels at pHs 5, 7, and 9. The AFGO concentration and media pH were evaluated and related to the suspension's microstructure and rheology. Graphene oxide (GO) nanosheets were synthesized using the modified Hummers method and functionalized with triethylenetetramine via microwave-assisted reaction to produce AFGO. The nanosheets were characterized by different techniques, such as scanning electron microscopy (SEM), thermogravimetric analysis, Raman spectroscopy, and x-ray photoelectron spectroscopy. The suspensions were characterized by rheological tests through steady-state and dynamic flow, zeta potential, and cryo-SEM for microstructure analysis. All samples presented a viscoplastic behavior and were modeled by the Herschel–Bulkley equation. Concerning the base hydrogels, the sample prepared at pH 9 showed lower viscosity, yield stress, and elastic modulus. At all pHs, the increase in the nanosheet concentration promotes a drop in the yield stress, viscosity, storage, and loss moduli. The cryomicrographs showed the impact of pH on the base hydrogel structure. It was also possible to observe that increasing nanoadditive concentration affects the Carbopol microgel swelling and weakens the suspension microstructure.

Magnetic amino-functionalized graphene oxide nanocomposite for PFAS removal from water

Magnetic amino-functionalized graphene oxide is a promising adsorbent for removing “forever chemicals” from water.

Improved corrosion protection performance of electrophoretic epoxy coatings with the incorporation of amino-functionalized graphene oxide

Improved corrosion protection performance of electrophoretic epoxy coatings with the incorporation of amino-functionalized graphene oxide

A long-term anti-corrosion and cathodic delamination resistant epoxy coating based on COF grafted GO nanofillers

Here, a long-term anti-corrosive epoxy (EP) coating based on nano-hybrid filler was developed. The surface of graphene oxide (GO) was aminated with (3-aminopropyl) triethoxysilane (APTES), and then the porous covalent organic framework (COF) was in-situ grown on amino functionalized graphene oxide (FGO) nanosheets by Schiff-based reaction to prepare FGO-COF nanofillers. Different characterization methods proved the successful modification of GO nanosheets with COF particles. The excellent water resistance of composite coatings was characterized through contact angle, adhesion, and water uptake tests. Transmission electron microscope (TEM) and molecular dynamics (MD) methods showed that the grafting of COF enhanced the dispersion and compatibility of GO in the coating. EIS measurements, salt spray analysis and cathodic delamination test indicated the significant improvements in the protective properties of the composite coatings compared with pure EP coating. The low-frequency impedance modulus of 1% FGO-COF composite coating reached higher than 6.8 × 109 Ω·cm2 after immersed in sea water for 60 days. In addition, the 1% FGO-COF composite coating performed only 34% delamination ratio after 120 h cathodic delamination test.

High proton conductivity of the phosphate-linked graphene oxide monolith over a wide range from subzero to moderate temperature

Achieving proton-conducting solids with high proton conductivity at subzero temperatures remains a serious challenge. Thus, it is indispensable to develop the composites with high conductivity ranging from subzero to medium temperatures (243–343 ​K). Graphene oxide (GO) as an alternative matrix can provide the rich oxygen-containing groups. Thus, we prepared a series of proton conductors by covalently linking phosphate units onto the amino-functionalized GO monoliths (denoted NGOM-P), the structures of which are determined by FT-IR, XPS, XRD and Raman characterization techniques. Further, the fast proton transfer in effective acid-base networks in NGOM-P make the monolith achieve high proton conductivity from 2.61 ​× ​10−2 ​S ​cm−1 (243 ​K) to 0.68 ​S ​cm−1 (343 ​K) under 98% relative humidity (RH).

Thiol-End-Group Dendrons Decorated with Gold Nanoparticles Immobilized on Amino-Functionalized Graphene Oxide for SERS Detection

Surface-enhanced Raman scattering (SERS) has abundant chemical fingerprint information to analyze complex analytes under aqueous conditions. However, SERS requires uniform metal particles to generate a hotspot effect and improve sensitivity and enhancement by localized surface plasmon resonance. Therefore, in this study, SERS detection chips have been developed using uniform gold nanoparticle (AuNP) arrays embedded on thiol-end-group dendritic polymers immobilized on amino-functionalized graphene oxide (AGO) thin films of transmission electron microscopy (TEM) grids. The graphene oxide (GO) thin film was fabricated by low-damage plasma with mixed gas (O2/H2) and then further functionalized by diethylenetriamine to form AGO substrates. Based on the efficient building block of dual-functional 4-isocyanato-4′-(3,3-dimethyl-2,4-dioxo-azetidino)-diphenylmethane (IDD), the 0.5 and 1.5 generations of thiol-end-functionalized poly(urea/malonamide) dendrons (DG0.5-SH and DG1.5-SH) were precisely synthesized and grafted onto AGO substrates. The interparticle gap of AuNPs could be well controlled and decorated on these thiol-end-group dendrons to achieve the optimal SERS enhancement effect by manipulating the sizes of AuNPs and generating dendrons. The results indicate that 31 nm AuNPs immobilized on the DG0.5-SH@AGO substrate exhibited reproducible and strong SERS enhancement compared with free AuNPs. Graphene-based SERS substrates provide rapid and stable SERS detection in solutions, which offers great potential for practical applications in detecting biomolecules and environmental pollutants.

Preparation and Anticorrosive Performance of Waterborne Epoxy Resin Composite Coating with Amino-Modified Graphene Oxide

A waterborne epoxy coating with superior corrosion resistance was developed by using a novel amino-functionalized graphene oxide (GO) that was modified by 2,5-diaminobenzenesulfonic acid. A battery of characterization methods, such as Fourier transform infrared spectroscopy (FT-IR), Raman spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), was used to prove that DGO was successfully prepared by grafting the amino of 2,5-diaminobenzenesulfonic on GO. The results indicated that the surface of DGO became rougher than GO, but a complete sheet structure was still maintained after modification; the optimal modified GO could be achieved when the mass ratio of 2,5-diaminobenzenesulfonic acid and GO was 5:1. The electrochemical impedance spectroscopy (EIS) tests indicated that the impedance at 0.01 Hz of a coating with 0.2 wt.% DGO still remained at a relatively high value after immersion for 48 h in 3.5 wt.% NaCl, which was about one order higher than a pure waterborne epoxy resin coating, and the corrosion current density decreased from 3.76 × 10-11 A/cm2 to 3.62 × 10-12 A/cm2. The dry adhesion and wet adhesion increased to 1.90 and 1.22 MPa, respectively, and the adhesion loss decreased from 53% to 36%. These interesting features could make waterborne epoxy coatings a promising anticorrosion coating for metal in long-term protection.

Amino-functionalized graphene oxide membranes for efficient separation of Sr2+ ions

Graphene oxide (GO) membranes were integrated with diverse nitrogen functional groups by subjecting to ammonia (NH3) vapours and evaluated for resultant changes in their chemical functioning and strontium (Sr) adsorption performance. Exposure to NH3 vapours amends the functional groups of GO, introduces amine, amide, ammonium functionalities and generates abundant sites prone to react with Sr2+ ions. The extent of GO restructuring and repercussions on Sr adsorption behaviour were examined using different GO precursors, NH3 treatment methods, membranes with varying GO mass and other nitrogen reagents namely, tri-isooctyl amine, pyridine, N,N-dimethyl acetamide. Nitrogen group functionalization enhances the Sr adsorption capacity of GO membranes nearly by two times, irrespective of the NH3 exposure duration and nature of precursor GO membranes. These NH3 subjected GO membranes displayed optimum Sr adsorption performance of ~475 mg/g, reusable at least for nine filtration cycles and importantly, capable of discharging 35–60 % of adsorbed Sr. The N-group supported Sr separation demonstrated in the present work is an energy efficient solid state membrane based procedure, which also lays a road map for development of amine, amide, ammonium functionalized GO layers and provides flexible platform for separation of all those toxic elements displaying affinity to complex with N-groups.

Modulation of Crystal Growth of an Energetic Metal–Organic Framework on the Surfaces of Graphene Derivatives for Improved Detonation Performance

Energetic materials are a special class of energy materials composed of C, H, O, and N. Their safety always deteriorates with increasing energy. Regulating the properties of energetic materials to meet application requirements is one of the focuses of research in this field. Energetic metal-organic frameworks (EMOFs) are good candidates as primary explosives to replace lead azide (LA) and other explosives containing toxic metal elements. However, safety remains the biggest concern in applications. In this paper, crystal morphology modulation of EMOF was carried out by stepwise coordination of metal ions and energetic ligands on surfaces of graphene oxide (GO) and amino-functionalized graphene oxide (AGO). Two energetic composite materials, Cu-AFTO@GO and Cu-AFTO@AGO, were successfully synthesized and also the EMOF (Cu-AFTO). The structures and morphologies of these materials were fully characterized. The thermal decomposition behaviors, mechanical sensitivity, and electrostatic discharge sensitivity were investigated in detail. The electric ignition ability of EMOF and two composite materials was tested. This study shows that it is possible to reduce the diameter of EMOF crystals from hundreds of microns to tens of nanometers by a stepwise coordination method. The high electrical conductivity and sensitivity-reducing effect of GO and/or AGO allow the nanosized EMOF crystals to have a lower ignition threshold and lower sensitivity.

Amino-functionalized graphene oxide supported in charcoal from the gasification of furniture scraps: From one-pot synthesis to wastewater remediation

Wood from furniture scraps were fed into a gasifier to produce clean energy, and its residual charcoal (FSC) was used as support for the development of an amino-functionalized multilayer graphene oxide (AmGO) composite. The AmGO supported on FSC (AmGO@FSC) and its pristine materials were characterized and then investigated as potential adsorbent of water pollutants. The supporting of AmGO on FSC consists in a two-way solution for environmental remediation, since a waste has been benefited to remove water pollutants. Moreover, supporting process eases the separation of the highly hydrophilic graphene oxide from the liquid medium, which is one of the main challenges in applying these nanomaterials. From equilibrium and kinetic studies, the maximum adsorption capacity at monolayer was 54.35 mg g−1, and equilibrium constant was 0.76 L mg−1, and Langmuir-Freundlich isotherm showed the best fit. Based on these studies, the predicted mechanisms of adsorption are governed by resistance to mass transfer in the bulk and liquid–solid film. Moreover, the molecules of Methylene Blue engaged the active sites of AmGO@FSC through π−π stacking and other weak interactions. Thermodynamic assays evidenced the spontaneity and the physical behavior of the adsorption, whilst the AmGO@FSC could be regenerated after six cycles. Finally, AmGO@FSC showed adsorptive capacity 2 times greater than its precursor material FSC. The great adsorptive capacity, high recoverability and easy separation bestow AmGO@FSC as one profitable adsorbent of textile dyes.

Role of low-dimensional carbon nanostructures in hybrid material as anticorrosive coating

In this work, different low-dimensional carbon nanostructures (graphite oxide, graphene oxide and amino-functionalized graphene oxide and graphite oxide) integrated into a hybrid, organic-inorganic matrix, were developed, obtaining different nanocomposite coatings. The hybrid matrix was obtained from an inorganic component, tetraethyl orthosilicate, and an organic composition resin, diglycidyl ether bisphenol-A. Each of the different coatings were separately applied on AISI 1018 carbon steel surfaces. The corrosion test was carried out by Electrochemical Impedance Spectroscopy on the coated metal in two different media, saline and acidic. The resistance to charge transfer was higher for coating containing graphene oxide in both electrolytes. A comparison between the coating's performance containing graphite oxide and graphene oxide showed that the exfoliation of graphite oxide is important to have a greater distribution and intercalation of the low dimensionality sheets inside the hybrid matrix up to form a uniform protective barrier. Wear test were carried out and structural stability of the coatings after 100 cycles was demonstrated, showing the persistent SiOSi groups produce a protection against corrosion to AISI 1018 carbon steel.

High-efficiency removal of cationic dye and heavy metal ions from aqueous solution using amino-functionalized graphene oxide, adsorption isotherms, kinetics studies, and mechanism.

GO-NH2 (amino functionalized graphene oxide) was synthesized by grafting (3-aminopropyl) triethoxysilane onto the surface GO (graphene oxide). The GO-NH2 with a higher surface area and many active sites was characterized and its effectiveness in removing Rhod B dye and Ni(II) ions from wastewater by adsorption was observed. The effects of pH, time, and strange ions on the adsorption efficiency were investigated. The equilibrium isotherm data confirmed that it fits the Langmuir and Freundlich isotherm models. GO and GO-NH2 exhibited high adsorption capacity (QM); 2500 (mg L-1) and 3333 (mg L-1) for Rhod B dye, and 312.5 (mg L-1), and 714.28 (mg L-1) for Ni(II) ions, respectively. The kinetics of adsorption was studied using pseudo-first-order, pseudo-second-order, intraparticle diffusion, and the Boyd model. It was found that the adsorption followed pseudo-second-order and film diffusion model are effective in this adsorption process. Adsorption mechanisms have been attributed to possible electrostatic attractions, hydrogen bonding, and interactions. In summary, the experimental results showed the synthesized GO and GO-NH2 would be promising adsorbents to remove aqueous solutions contaminated with Rhod B dye and Ni(II) ions.

Graphene oxide activates B cells with upregulation of granzyme B expression: evidence at the single-cell level for its immune-modulatory properties and anticancer activity.

We recently found by single-cell mass cytometry that ex vivo human B cells internalize graphene oxide (GO). The functional impact of such uptake on B cells remains unexplored. Here, we disclosed the effects of GO and amino-functionalized GO (GONH2) interacting with human B cells in vitro and ex vivo at the protein and gene expression levels. Moreover, our study considered three different subpopulations of B cells and their functionality in terms of: (i) cytokine production, (ii) activation markers, (iii) killing activity towards cancer cells. Single-cell mass cytometry screening revealed the higher impact of GO on cell viability towards naïve, memory, and plasma B cell subsets. Different cytokines such as granzyme B (GrB) and activation markers, like CD69, CD80, CD138, and CD38, were differently regulated by GONH2 compared to GO, supporting possible diverse B cell activation paths. Moreover, co-culture experiments also suggest the functional ability of both GOs to activate B cells and therefore enhance the toxicity towards HeLa cancer cell line. Complete transcriptomic analysis on a B cell line highlighted the distinctive GO and GONH2 elicited responses, inducing pathways such as B cell receptor and CD40 signaling pathways, key players for GrB secretion. B cells were regularly left behind the scenes in graphene biological studies; our results may open new horizons in the development of GO-based immune-modulatory strategies having B cell as main actors.

Preparation and properties of a self-crosslinking styrene acrylic emulsion using amino-functional graphene oxide as a crosslinking agent and anti-corrosion filler

In this paper, we prepared a self-crosslinking amino-functional graphene oxide/styrene acrylic hybrid emulsion (AGO/SA). The styrene acrylic emulsion (SA) was synthesized with acetoacetoxyethyl methacrylate (AAEM) by semicontinuous seeded emulsion polymerization. Then, amino-functionalized graphene oxide (AGO) was prepared via the modification of graphene oxide (GO) with 3-aminopropyltriethoxysilane (APTES) and reacted with the SA emulsion as a crosslinking agent by in situ polymerization. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal gravity analysis (TGA), and transmission electron microscopy (TEM) were applied to explore the chemical structures and morphologies of the samples. The anti-corrosion performance of the AGO/SA coatings was evaluated by Tafel polarization and electrochemical impedance spectroscopy (EIS). Along with the crosslink between AGO and SA, the micropores in the matrix were reduced, the coating expressed improved corrosion resistance due to the graphene barrier, and the hybrid emulsion with 0.7 wt.% AGO exhibited the best anti-corrosion properties. These results indicate that AGO can act as both a crosslinking agent and an anti-corrosion agent in self-crosslinking hybrid emulsions, which have great potential in the field of environmentally friendly emulsions.

PH-Induced Electrostatic Interaction between Polyacrylates and Amino-Functionalized Graphene Oxide on Stability and Coating Performances.

Electrostatic interaction between polymers and nanofillers is of great importance for the properties and design of their composites. Polyacrylates with carboxyl, hydroxyl and acylamino groups were synthesized via emulsion polymerization and marked as P(MMA-BA-AA), P(MMA-BA-HEA) and P(MMA-BA-AM), respectively. Amino-functionalized graphene oxide (NGO) was prepared by Hoffman rearrangement using GO as the raw material. The polyacrylate composites were prepared by mixing NGO with each of the three kinds of polyacrylate. Effects of pH and NGO amounts on the properties of polyacrylate composites were studied. It was found that the surface charge of polyacrylate and NGO had the greatest effect on the composite properties. P(MMA-BA-AM)/NGO was not stable at any pH (2–8). With the same NGO amount of 0.1 wt%, the toughening effect of NGO on P(MMA-BA-AA) was larger than that on P(MMA-BA-HEA). The break strength of P(MMA-BA-AA)/NGO and P(MMA-BA-HEA)/NGO increased to 5.22 MPa by 47% and 3.08 MPa by 31%, respectively. NGO could increase the thermal stability of P(MMA-BA-AA) and P(MMA-BA-HEA) to different degrees. The polyacrylate film-forming processes were tested, and it showed that NGO influenced polyacrylate through the whole film-forming process. The results provide potential methods for the design of polymer-based nanocomposites.