Graphite Oxide Hybrid Research Articles

Study of the dielectric heating of graphite oxide and its effect on the microwave‐assisted synthesis of Nylon‐6/graphite oxide polymeric hybrid nanocomposites

AbstractThe present research focuses on the study of the microwave dielectric heating (DH) of graphite oxide (GrO) during the synthesis of Nylon‐6/GrO hybrid polymeric nanocomposites (HPNCs) employing different microwave input powers and two GrO morphologies. In this regard, we evaluated GrO powder (GrOP) with dimensions ranging from nanometers to microns and GrO films (GrOF) with millimeter lengths and micron thicknesses. Both morphologies show the same oxidation degree and concentration of functional groups. However, they differ in the number of stacked graphene oxide sheets, thus modify their surface area. The results indicated that the morphology of GrO plays a determining role in its DH behavior in the microwave‐assisted polymerization (MAP). On one hand, GrOF contains a high concentration of graphene sheets that induce both an increase in DH and the formation of hot spots. In addition, GrOF has a greater attractive force between its sheets, since its interlamellar space is smaller than 8.4 Å, which makes its exfoliation more difficult. The aforementioned effects significantly reduce the exfoliation and hybridization of GrOF. On the other hand, the larger interlamellar spacing in GrOP weakens the attractive forces compared to GrOF. The lower concentration of graphene oxide lamellae prevents the formation of hot spots, and homogeneously dissipates DH in the reaction medium, maximizing its exfoliation and hybridization. In addition, its behavior presents a defined trend concerning time. These results highlight the importance of considering the GrO morphology in the synthesis of HPNCs as it globally affects the MAPs process, as well as GrO reduction, exfoliation, and hybridization.

Electrophoretic deposition of antimony/reduced graphite oxide hybrid nanostructure: A stable anode for lithium-ion batteries

Rechargeable batteries are ubiquitous in today’s world and find numerous applications starting from electronic gadgets to electric vehicles owing to their high energy density and battery life. Antimony (Sb) is considered a promising alternative anode to graphite, offering excellent theoretical capacity (660 mAh g−1) for the development of high energy density lithium-ion batteries (LIBs). However, Sb suffers from rapid capacity fade during galvanostatic cycling in LIBs owing to intrinsic volumetric strain (∼135%). Here, we demonstrate poly(acrylic acid) and nickel nitrate assisted electrophoretic deposition (EPD) of Sb/RGO anode on the copper foil is a viable option for electrode preparation over traditional doctor blade tape casting route. The EPD-Sb/RGO anode offers a stable discharge and charge capacity of ∼498.1 mAh g−1 and ∼497.8 mAh g−1, respectively, up to 100 cycles at a high current rate of 0.5 A g−1. Microstructural analysis shows that Sb and RGO deposited uniformly on copper foil and develop a sandwich-like structure of Sb nanoparticles interspersed in-between RGO planes. It is demonstrated that poly(acrylic acid) and nickel nitrate assisted sterically stabilized Sb/RGO composite mass remains intact on Cu foil post 100 cycles for EPD-Sb/RGO electrode may be the reason for stable capacity, conspicuously absent for electrode prepared by tape casting route.

Fabrication of metal-organic frameworks and graphite oxide hybrid composites for solid-phase extraction and preconcentration of luteolin

A novel solid-phase extraction sorbent, metal-organic frameworks and graphite oxide hybrid composite, was prepared by a solvothermal technique. The morphology and properties of the resultant material were examined by Fourier transform infrared spectroscopy, X-ray diffraction and field emission scanning electron microscopy. To evaluate the extraction performance of the resultant sorbent, luteolin was chosen as a model analyte. The extraction conditions were optimized. Based on these, a convenient and efficient solid-phase extraction procedure for the determination of luteolin was established and the subsequent quantification step was performed by square wave anodic stripping voltammetry. Under the optimal conditions, the oxidation current increased linearly with increasing the concentration of luteolin in the range of 5.0 × 10(-9)-5.0 × 10(-7)molL(-1) with a correlation coefficient of 0.9983 and a detection limit of 7.9 × 10(-10)molL(-1). The relative standard deviation of seven successive scans was 4.20% for 5.0 × 10(-8)molL(-1) luteolin. This work not only proposes a useful method for sample pretreatment, but also reveals the great potential of metal-organic frameworks based hybrid materials as an excellent sorbent in solid-phase extraction.

Modifying graphite oxide with grafted methyl acrylate brushes for the attachment of magnetite nanoparticles

Surface-grafted polymer brushes of methyl acrylate of graphite oxide (GO) have been constructed to anchor poly(amidoamine) 2.0G (PAMAM 2.0G) dendrites for the attachment of magnetite nanoparticles. Monomers of methyl acrylate were copolymerized on the GO sheets by atom transfer radical polymerization. Then the PAMAM 2.0G was attached via covalent bond at the end of the grafted chains. Thus the inexpensive Fe(III) of ferric trichloride could coordinate with the remaining amino groups of PAMAM 2.0G and were reduced by the added sodium borohydrite at appropriate pH value to obtain nano magnetite-decorated GO hybrid materials. The hybrids exhibited a powerful catalysis on the degradation of aqueous solutions of hydroquinone.

Metal-organic framework-199/graphite oxide hybrid composites coated solid-phase microextraction fibers coupled with gas chromatography for determination of organochlorine pesticides from complicated samples

The hybrid material of a copper-based metal-organic framework (MOF-199) and graphite oxide (GO) was explored as the solid-phase microextraction (SPME) coating for the first time. This fiber was fabricated by using 3-amino-propyltriethoxysilane (APTES) as the cross-linking agent, which enhanced its durability and allowed more than 140 replicate extractions. With the incorporation of GO, the MOF-199/GO fibers with GO contents ranging from 5 to 15wt% exhibited enhanced adsorption affinity to organochlorine pesticides (OCPs) compared to MOF or GO individually. This improvement was linked to the enhanced dispersive forces (increased volume of small pores) that provided by the dense carbon layers of GO. Combining the superior properties of high porosity of MOFs and the unique layered character of GO, the MOF-199/GO (10wt%) fiber exhibited higher adsorption affinity to some OCPs than commercial polydimethylsiloxane (PDMS) and polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibers. This new fiber was developed for headspace (HS) SPME of eight OCPs followed by GC/ECD analysis. The limits of detection were 2.3–6.9ng/L. The relative standard deviation (RSD) for five replicate extractions using one fiber ranged from 5.3% to 8.8%. The fiber-to-fiber reproducibility was 5.2–12.8%. This method was successfully used for simultaneous determination of eight OCPs from river water, soil, water convolvulus and longan with satisfactory recoveries of 90.6–104.4%, 82.7–96.8%, 72.2–107.7% and 82.8–94.3%, respectively. These results indicated the MOF-199/GO composite provided a promising alternative in sample pretreatment.

Synthesis and characterization of a poly(aniline-based disulfide)/diisocyanate-modified graphite oxide hybrid by a grafting technique

Di-isocyanate-modified graphite oxide ( iGO) was obtained by surface grafting of graphite oxide with toluene diisocyanate. A hybrid of iGO with 5-amino-1,4-dihydrobenzo[d]-1′,2′-dithiadiene (DTAn)/aniline (An) copolymer [P(DTAn-co-An)] was synthesized by a grafting technique. The reaction between the –NH 2 groups of the P(DTAn-co-An) and the –NCO groups of the iGO was proved by Fourier-transform infrared spectra. The X-ray diffraction and transmission electron microscopy showed that the lamellar structure of the hybrid was destroyed and the nanofiber-like P(DTAn-co-An) was deposited on the surface of the iGO nanosheets. Compared to the P(DTAn-co-An), the electrochemical cycling stability of the hybrid was significantly improved due to the covalent interaction between the P(DTAn-co-An) and the iGO.

Effective post treatment for preparing highly conductive carbon nanotube/reduced graphite oxide hybrid films

SWCNT-reduced graphite oxide hybrid films were prepared by a filtration method. An efficient post-treatment procedure was designed to reduce GO and remove dispersants simultaneously. The sheet resistance decreased significantly after treatment, by a factor of 4-13 times. Films with excellent performance (95.6%, 655 Ω per square) were obtained and had great potential applications.

MOF/graphite oxide hybrid materials: exploring the new concept of adsorbents and catalysts

Two types of metal-organic framework (MOF)/graphite oxide hybrid materials were prepared. One is based on a zinc-containing, MOF-5 and the other on a copper-containing HKUST-1. The materials are characterized by X-ray diffraction, sorption of nitrogen, thermal analyses, Fourier Transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Their features are compared to the ones of the parent materials. The water stability and ammonia adsorption capacity of the hybrid materials were also evaluated. It was found that the latter compounds exhibit features similar to the ones of the parent MOF. In most cases, their porosity increased compared to the one calculated considering the physical mixture of MOF and GO. This new porosity likely located between the two components of the hybrid materials is responsible for the enhanced ammonia adsorption capacity of the compounds. However, for both the zinc-based and the copper-based materials (MOFs and hybrid materials), a collapse of the framework was observed as a result of ammonia adsorption. This collapse is caused by the interactions of ammonia with the metallic centers of MOFs either by hydrogen bonding (zinc-based materials) or coordination and subsequent complexation (copper-based materials). Whereas the MOF-5 based compounds collapse in presence of humidity, the copper-based materials are stable.

Inorganic–organic hybrid porous materials based on graphite oxide sheets

Graphite oxide hybrid porous materials were constructed by the cross-linking of graphite oxide sheets using the reaction of organic diisocyanates with the carboxyl and hydroxyl groups on both sides of the sheets. In the inorganic–organic hybrid materials, graphite oxide sheets are building blocks and the diisocyanates are covalent cross-linkers acting as spacers between the sheets. Infrared spectroscopy verified the chemical functionalization of the carboxyl and hydroxyl groups. Raman spectroscopy demonstrated that the skeleton structure of graphite oxide remains after diisocyanate treatment. Nitrogen sorption analysis revealed a much larger surface area of the obtained porous materials compared with that of the powdery graphite oxide, indicating that diisocyanate molecules act as covalently linked nanoscale spacers between the sheets and effectively limit their face-to-face stacking.