Surface Of Graphene Oxide Nanosheets Research Articles

Radiolabeled florescent-magnetic graphene oxide nanosheets: probing the biodistribution of a potential PET-MRI hybrid imaging agent for detection of fibrosarcoma tumor.

Radiolabeled graphene oxide (GO) nanosheets has been one of the most extensively studied nanoplatform for in vivo radioisotope delivery. Herein, we describe the functionalization of the surface of GO nanosheets with Fe3O4 magnetic nanoparticles, cysteine amino acid as an interface ligand, and cadmium telluride quantum dots. To enable In vivo PET imaging, the GO@Fe3O4-cys-CdTe QDs were labeled with 68Ga to yield [68Ga] Ga-Go@ Fe3O4-Cys-CdTe QDs. Furthermore, serum stability tests were performed and the biological behavior of the nanocomposite was evaluated in rats bearing fibrosarcoma tumor. Liver, blood and tumor were the most accumulated sites at 1 h after the injection, and the radiolabeled nanocomposite as a PET/MRI imaging agent showed fast depletion from body and acceptable tumor uptake. Magnetic (Fe3O4) and fluorescent components (CdTe QDs) along with a positron-emitting radionuclide will help to design a multimodal imaging system (PET/MRI/OI) which will offer the advantages of combined imaging techniques and further possible used in localized radionuclide therapy. Overall, [68Ga] Ga-GO@Fe3O4-cys-CdTe QDs nanocomposite shows great promise as a radiolabeled imaging agent owing to high accumulation in tumor region.

Sulfonic acid (-HSO3) functionalization effect on graphene oxide membrane by (3 mercaptopropyl) trimethoxysilane and their applications in hydrogen membrane fuel cells

Conventional proton exchange membrane fuel cells (PEMFCs) use a perfluorinated ionomer membrane, e.g., Nafion®, which is expensive and subject to a rigorous synthesis process. Graphene oxide membrane (GOM) is acknowledged as a promising alternative electrolyte due to its hydrophilic nature and attractive proton conductivity in wet conditions. However, GOM loses its negative surface functional groups by hydrogen gas at the anode during operation in PEMFCs, resulting in increased electronic conductivity. In addition, two-dimensional graphene oxide (GO) nanosheets exhibited a larger anisotropy difference in proton conductivity compared to Nafion®. In this study, (3-mercaptopropyl)trimethoxysilane (MPTS, HS(CH2)3Si(OCH3)3) was reacted with the surface of GO nanosheet (M-GOM) by vigorous stirring, where unreacted MPTS was partially removed by a rinsing cycle except the M-GOM powder. Reactive MPTS has two essential reactions which were carried out by forming a hydrolysis reaction (Si-OCH3 to Si-OH) and a condensation reaction (Si-OH to Si-O-Si). The thiol groups of MPTS were oxidized to sulfonic acid groups (-HSO3) to provide high proton conducting stations with GO functional groups (M-GOM/oxid) and compared with non-oxidized thiol groups in a GO matrix (M-GOM/unoxid). The superior –HSO3 effect on M-GOM have reported for proton conductivity, physicochemical properties, ion exchange capacity, thermal stability, gas permeability and fuel cell performance. Furthermore, a hydrogen-permeable metal layer was deposited by a DC magnetron sputter to increase mechanical strength and reduce fuel crossover. A dual-layer membrane composed of M-GOM/unoxid or M-GOM/oxid and Pd thin film was analyzed as an electrolyte for a hydrogen membrane fuel cell (HMFC), which simultaneously performs two roles, an anode catalyst and an electrolyte.

Self-assembled cobalt disulfide-graphene oxide composite for efficient and environmentally friendly removal of antibiotic ornidazole through PMS activation

In this study, a highly active peroxymonosulfate (PMS) activator was prepared by the self-assembly of cobalt disulphide (CoS2) nanoparticles on the surface of graphene oxide nanosheets using a simple electrostatic self-assembly method. The catalysts were characterized, and their ability to activate PMS to eliminate ornidazole (ORZ) was assessed. Degradation experiments showed that the CoS2−GO/PMS system exhibited excellent ORZ degradation performance, removing 99.7 % of ORZ in 10 min. In four consecutive cycles, the reduction rate of ORZ removal by the composite catalyst decreased by only 1.8 %. Both radical quenching experiments and electron paramagnetic resonance (EPR) tests revealed that sulfate radical (SO4•-) and superoxide radical (O2•-) contributed to the major reactive oxygen species (ROS). X-ray photoelectron spectroscopy (XPS) results showed that the sulfur (S) species in CoS2 played an important role in the Co(III)/Co(II) cycle, driving the catalyst to exhibit excellent PMS activation. Liquid chromatography-mass spectrometry (LC-MS) was used to determine the possible decomposition processes and identify the intermediates of the ORZ medium. Remarkably, the biotoxicity assessment of degraded intermediates analyzed by ECOSAR software indicated the environmentally friendly features of the degradation process.

Nanoplasmonic engineering construction of europium oxide incorporated on graphene oxide surface and its nano heterojunction through the zinc oxide nanoparticles for water-clean

The redesigned engineering building of europium (III) oxide nanoparticles and zinc oxide nanoparticles on the electron carrier surface of graphene oxide nanosheet is the main target to increase the effectiveness of the electron transfer and photogeneration of reactive oxygen species for the photocatalytic and adsorption process. The hybrid nanocomposite fabricates by the precipitation and grinding method and characterization of the nanocomposite perform by various techniques, such as field emission scanning electron microscopy (FEG-SEM), FT-IR spectroscopy, zeta potential, and UV–visible spectrophotometer. The hybrid nanocomposite's stability is performed through the cyclic voltammetry technique by measuring the CV-cycle's multi-cycles. The adsorption process and photocatalytic activity are detected by using the UV–visible spectroscopy, where the degradation efficiency of characterized absorption peaks of pollutants was followed. The ability of the modified surface of hybrid nanocomposite against the pollutants for example methylene blue dye, p-nitrocatechol, p-nitrophenol, and removal of the chromium heavy metal to obtain the clean water was performed successfully. The rate constant and efficiency of the fabricated nanocatalyst were calculated, the photodegradation of methylene blue was 0.005 min−1 (efficiency 68 %), in sodium hydroxide was 0.03764 min−1 (efficiency 94 %), and in hydrogen peroxide was 0.02837 min−1 (efficiency 96 %). The p-nitrocatechol has photodegradation at 5.7564 min−1 (efficiency 89 %), p-nitrophenol 0.00492 min−1 (efficiency 74 %), and chromium ions adsorption appeared at 0.13381 min−1 (efficiency 54 %). The study confirms the hybrid nanocomposite is a promising candidate as a novel membrane for clean water production.

Composite Membrane Based on Graphene Oxide and Carboxymethylcellulose from Local Kazakh Raw Materials for Possible Applications in Electronic Devices

The synthesis of new composite nanomaterials based on graphene oxide (GO)modified with cellulose and its derivatives, as well as nanocellulose, is currently an important direction and contributes toward solving many problems in various fields such as nanotechnology, information technology, medicine, high-dielectric materials, and nanoelectronics. In this work, for the first time, for the production of GO and its membrane with carboxymethylcellulose (CMC), local Kazakhstan “Ognevsky” graphite was used as the initial raw material. In this regard, the preparation of nanocomposites of GO modified with cellulose derivatives, including CMC, attracts great interest from scientists and expands its field of practical application due to the significant changes in its physicochemical properties. In this work, the GO obtained using the Hummers method was modified by CMC, and its physicochemical, structural, and electrical characteristics were studied. The GO/CMC membrane was synthesized by mixing 1% GO with crushed solid mass of CMC (0.03 g; 0.06 g; 0.15 g) and then processing using ultrasound. The surface morphology of the GO/CMC membrane was studied using scanning electron microscopy (SEM). It has been established that by increasing the mass of CMC (0.03 g; 0.06 g; 0.15 g), the polymerization of CMC occurs on the surface of GO nanosheets. Cross-sectional micrographs of GO/CMC show the formation of sandwich-like layered structures. The synthesis efficiency (yield) of GO from synthetic graphite is 10.8%, and GO from Ognevsky graphite is 11.9%, almost 1.1% more than GO from synthetic graphite. The mechanical tensile strength increases from 2.3 MPa to 14.3 MPa and the Young’s modulus from 2.3 MPa to 143 MPa. The electrical parameters of the humidity sensor based on GO and GO/CMC membranes (0.03 g; 0.06 g; 0.15 g) were studied as a function of humidity to determine the performance of the device.

Experimental Investigation of Mechanical Properties of Clay–Cement Slurry Containing Graphene Oxide

As a widely used material in underground engineering, clay–cement slurry grouting is known for its initial poor anti-seepage and filtration capacity, the low strength of the resulting stone body, and its tendency towards brittle failure. To explore efficient and environmentally friendly grouting materials, industrial-grade graphene oxide (GO) was incorporated into a clay–cement slurry to create a new type of slurry called a GO composite. These GO composites were then utilized to reinforce fractured formations. Uniaxial compression tests, shear strength tests, permeability tests, and electron microscopy scans were conducted to investigate the strength, permeability, and microscopic features of the GO composite-reinforced fractured formations. Furthermore, the optimization effect and application prospects of graphene oxide on clay–cement slurry materials were evaluated. The experimental results demonstrated that the modified slurry effectively improved the compressive strength (increased by 7.2% to 32.5%) and shear strength (increased by 28.6% to 105.3%) of consolidated fractured gravel. By conducting orthogonal experiments with range analysis, variance analysis, and multiple regression analysis, it was shown that there was a strong correlation between the consolidated body and three factors influencing the permeability coefficient. Among these factors, the OPC content had the most significant impact on the permeability coefficient, followed by the GO content. Graphene oxide was found to promote cement hydration reactions, guide the growth of hydration products on the surface of graphene oxide nanosheets, optimize the pore structure in grouting materials, and reduce microcracks between the slurry and the fractured gravel interface. Electron microscopy characterization and fractal analysis revealed that the addition of graphene oxide effectively reduced the degree of microdamage during the sample’s failure process. This ensured the integrity of the sample during the unstable failure process, enhanced the material’s toughness, and improved its ability to resist loads.

Multi-treatments based on polydimethylsiloxane and metal-organic framework wrapped with graphene oxide for achieving long-term corrosion and fouling protection: experimental and density functional theory aspects

In this study, ZIF-8 metal–organic framework decorated on surface of graphene oxide nanosheets and functionalized with silane moieties (F-GO@MOF) is employed to enhance the anti-corrosion, anti-bacterial, and anti-fouling properties of epoxy coatings modified with polydimethylsiloxane (epoxy-PDMS). The epoxy-PDMS/F-GO@MOF sample has revealed super-hydrophobic behavior with least water contact angle changes (Δθ ≈ 5° while Δθ ≈ 17° is recorded for epoxy-PDMS sample) during 20 days of immersion, twice pull-off adhesion strength (6.8 MPa compared to 3.7 MPa for epoxy-PDMS coating), and significantly higher impedance modulus (8.82 × 108 Ω·cm2 which is 3 times more than the epoxy-PDMS sample) during 60 days of immersion in NaCl electrolyte. The anti-bacterial test against Pseudomonas sp. and anti-fouling monitoring in Qingdao port have shown that fewer bacteria and marine organisms are attached on the epoxy-PDMS/F-GO@MOF coating, respectively, indicating advanced fouling and bacterial resistance of the nanocomposite sample. Based on the theoretical studies by density functional theory (DFT) method, the binding of the components in the GO@MOF complex is notably large which could inhibit the penetration of corrosive agents toward the steel substrate. In addition, the stabilization of the GO@MOF nanohybrid is mainly controlled through van der Waals (vdW) forces.

Lacunary Polyoxometalate iImmobilized on Graphene Oxide: An Effective Electrocatalyst for Hydrogen Generation in Aqueous Solution

AbstractA new stable nanocomposite comprising thiol‐functionalized lacunary Keggin‐type phosphomolybdate (PMo11) and graphene oxide (GO) was prepared via the thiol‐ene click reaction. Various characterization techniques, like FT‐IR spectroscopy, energy‐dispersive X‐ray (EDX) spectroscopy, and X‐ray diffraction (XRD) analysis showed the strong covalent interaction of GO and PMo11 species and successful formation of PMo11−S−GO nanocomposite. Nitrogen adsorption‐desorption analysis revealed the decrease in GO surface area after introducing PMo11 species. The prepared nanocomposite was employed in the electrocatalytic hydrogen evolution reaction (HER) in 0.5 M H2SO4 solution. A low overpotential of 335 mV and small Tafel slope of 71 mV.dec−1 were obtained in electrocatalytic HER experiments. The nanocomposite exhibited high stability and negligible loss of electrocatalytic activity for at least 850 cycles which is a result of the stable covalent attachment of lacunary Keggin type phosphomolybdate to the surface of GO nanosheets.

Facile fabrication of the hybrid of amorphous FePO4·2H2O and GO toward high performance sodium-ion batteries

Iron phosphate (FePO4) with moderate working voltage is an appealing cathode material for room temperature rechargeable sodium-ion batteries (SIBs), while the low electronic conductivity and poor cycle performance remarkably impede its possible energy storage applications. In this work, we report a simple route to fabricate graphene oxide (GO) hybridized amorphous FePO4·2H2O composite for SIBs. By directly mixing FeCl3·6H2O and GO (mass controlled by x wt% of the mass of FeCl3·6H2O) in an agate mortar with pestle, Fe3+ ions could be bound by the oxygen-containing functionalities on the surface of GO nanosheets. After adding NH4H2PO4 powder to the above mixture, a direct room temperature solid state reaction between the GO-confined Fe3+ ions and PO43− polyanions results in an in-situ hybridization of amorphous FePO4·2H2O and GO, i.e. the target electroactive material (denoted as FePO4@GO-x) is attained. In-depth mechanism for the solid state reaction is demonstrated by FTIR and XPS techniques. The optimized hybrid of amorphous FePO4·2H2O and GO (FePO4@GO-15 composite) exhibits the best sodium storage performance. A high reversible charge capacity of 129.0 mAh g−1 is delivered at a current density of 100 mA g−1 for the first cycle, which is around 90% of the theoretical capacity (144 mAh g−1) of FePO4·2H2O. The composite also exhibits outstanding rate performance, superior reversibility, and satisfactory long-lasting cycle stability. When cycled at a high current density (800 mA g−1 at 31 °C), the composite cathode still delivers a charge capacity of 51 mAh g−1 over 1000 cycles, corresponding to 67% of the first charge capacity. The results presented clearly indicate that the hybrid of amorphous FePO4·2H2O and GO is a promising cathode material for SIBs.

Functionalized graphene oxide-based lamellar membranes for organic solvent nanofiltration applications.

In this study, two-dimensional graphene oxide-based novel membranes were fabricated by modifying the surface of graphene oxide nanosheets with six-armed poly(ethylene glycol) (PEG) at room conditions. The as-modified PEGylated graphene oxide (PGO) membranes with unique layered structures and large interlayer spacing (∼1.12 nm) were utilized for organic solvent nanofiltration applications. The as-prepared 350 nm-thick PGO membrane offers a superior separation (>99%) against evans blue, methylene blue and rhodamine B dyes along with high methanol permeance ∼ 155 ± 10 L m-2 h-1, which is 10-100 times high compared to pristine GO membranes. Additionally, these membranes are stable for up to 20 days in organic solvent. Hence the results suggested that the as-synthesized PGO membranes with superior separation efficiency for dye molecules in organic solvent can be used in future for organic solvent nanofiltration application.

SYNTHESIS OF COMPOSITE MEMBRANE BASED ON GRAPHENE OXIDE AND NANOSTARCH

Intensive research of nanocomposites contributes to the development of new materials in the fields of medicine, nanoelectronics, high dielectric materials, energy, biotechnology and information technology. Therefore, the synthesis of new materials by modifying of grapheme oxide with nanostarch and the study of its properties are of great interest. In this study, nanocomposite membrane was synthesized by modifying of graphene oxide in a 1:1 volume ratio with nanostarch and their chemical structures were studied by fourier-transform infrared spectroscopy and ultraviolet spectroscopy. The results of the study showed the absorption of the etheric bond C=O in the ultraviolet spectrum at full length was 243 nm. The infrared spectrum showed new etheric bonds O=C-OH at a wavelength of 1150 cm-1. The scanning electron microscopy analysis indicates that grapheme oxide is homogeneously coated by starch, it means that nanostarch was successfully polymerized on the surfaces of graphene oxide nanosheets and formed sandwich-like structures. The X-Ray diffraction analysis indicatedthat the crystalline structure changes to amorphous to a certain extent due to the ester bond formed between graphene oxide and starch. The electrical properties showed the resistivity of the initial graphene oxide was ρ = 5.53·103 Ohm·m and after its modification by starch, the resistivity of the graphene oxide/starch membrane increased by 2 orders, which was equal to 2.59·105 Ohm·m. According to the results, high dielectric materials are very important in electrical and electronics engineering. Therefore, there is no doubt that there will be great interest in this field.

Study on Properties of Epoxy Composites Modified by Functional Graphite Oxide and Polyurethane

To improve the performance of the epoxy resin, isophorone diisocyanate (IPDI)-modified graphene oxide (GO) nanosheets were used, and the modified graphene oxide (iGO) was grafted with epoxy resin using polyurethane (PU) chain segments as a bridge to prepare epoxy composites. The iGO was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction analysis (XRD), and transmission electron microscopy (TEM), and the results showed that IPDI increased the layer spacing of iGO from 0.79 nm to 1.06 nm by grafting with hydroxyl and carboxyl groups on the surface of GO nanosheets, which improved the degree of exfoliation of iGO. Tensile testing, dynamic thermomechanical analysis (DMA), and scanning electron microscopy (SEM) were used to figure out the thermomechanical properties of the modified epoxy composites. The results show that the tensile strength and elongation at break of the as-prepared 0.5% iGO-PU/EP composites are 0.2 and 6.3 times higher than those of pure EP, respectively, and that the glass transition temperature was raised by about 2°C, with a significant increase in crosslinking.

Vertical and uniform growth of MoS2 nanosheets on GO nanosheets for efficient mechanical reinforcement in polymer scaffold

ABSTRACT Graphene oxide (GO) and molybdenum disulphide (MoS2), have drawn more and more attention as reinforcement in polymer. However, their large specific surface area and strong van der Waals forces result in serious aggregations in polymer matrix, which restrains the reinforcement effect. In this study, MoS2 nanosheets were in situ synthesised vertically and uniformly on the surface of GO nanosheets with the help of a hexadecyl trimethyl ammonium bromide (CTAB) assisted hydrothermal process to facilitate their dispersion in polylactic acid (PLLA) scaffold manufactured via selective laser sintering (SLS). The experimental results revealed that the 1.5 wt% GO/MoS2 nanocomposite exhibited better dispersion state compared with the 1.5 wt% GO and 1.5 wt% MoS2 in PLLA matrix. Therefore, the PLLA scaffold loading 1.5 wt% GO/MoS2 presented 10.2 and 1461 MPa of tensile strength and modulus with enhancement of 61% and 58%, respectively, compared with the pure PLLA scaffold. The reinforcement mechanisms mainly included crack deflection, crack bridging, crack pinning and pulling out of GO/MoS2. What’s more, the GO/MoS2-PLLA scaffold possessed benign cytocompatibility for cell behaviour, suggesting hopeful applications in bone defect repair.

Silicon dioxide nanoparticles decorated on graphene oxide nanosheets and their application in poly(l-lactic acid) scaffold

IntroductionThe aggregation of graphene oxide (GO) is considered as main challenge, although GO possesses excellent mechanical properties which arouses widespread attention as reinforcement for polymers. ObjectivesIn this study, silicon dioxide (SiO2) nanoparticles were decorated onto surface of GO nanosheets through in situ growth method for promoting dispersion of GO in poly(l-lactic acid) (PLLA) bone scaffold. MethodsHydroxyl and carboxyl functional groups of GO provided sites for SiO2 nucleation, and SiO2 grew with hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) and finally formed nanoparticles onto surface of GO with covalent bonds. Then, the GO@ SiO2 nanocomposite was blended with PLLA for the fabrication of bone scaffold by selective laser sintering (SLS). ResultThe results indicated that the obtained SiO2 were distributed relatively uniformly on surface of GO under TEOS concentration of 0.10 mol/L (GO@SiO2-10), and the covering of SiO2 on GO could increase interlayer distance of GO nanosheets from 0.799 nm to 0.894 nm, thus reducing van der Waals forces between GO nanosheets and facilitating the dispersion. Tensile and compressive strength of scaffold containing GO@SiO2 hybrids were significantly enhanced, especially for the scaffold containing GO@SiO2-10 hybrids with enhancement of 30.95 % in tensile strength and 66.33 % in compressive strength compared with the scaffold containing GO. Additionally, cell adhesion and fluorescence experiments demonstrated excellent cytocompatibility of the scaffold. ConclusionsThe good dispersion of GO@SiO2 enhances the mechanical properties and cytocompatibility of scaffold, making it a potential candidate for bone tissue engineering applications.

Synthesis and preparation of poly (AM-co-AMPS)/GO nanocomposites hydrogel as a rheology modifier and fluid loss controller for use in oil well cementing

The aim of the present work is to evaluate the influence of graphene oxide (GO) on copolymer nanocomposites hydrogel structure based on acrylamide (AM) and 2-acryloamido-2-methylpropane sulfonic acid (AMPS) in the presence of the N, N-methylene-bis-acryl-amide (NMBA) by the free radical copolymerization technique. The influence of poly (AM-co-AMPS)/GO as a rheology modifier along with fluid loss controller on the rheological and mechanical properties of brine cement slurry was also investigated. The characterization results confirmed the synthesis of AM monomer and AMPS and showed their grafting with GO surface. The poly (AM-co-AMPS)/GO hydrogel improved the rheological properties of the cement slurry as compared to conventional cement slurry. Furthermore, free water and fluid loss of cement slurry declined by adding the copolymer nanocomposites hydrogel at elevated temperatures. Moreover, not only the thickening time of cement slurry dropped but also, the compressive strength increased with a rise of nanocomposites hydrogel concentrations. However, the nanocomposite hydrogels showed a great effect on early compressive strength than the final compressive strength. The results of this investigation revealed the excellent performance of crosslinked structure of copolymer nanocomposites hydrogel due to the linking of sulfonated AMPS and AM on the surface of GO nanosheet in the attendance of NMBA. This renders greater stability to the cement slurry against salinity and temperature changing of well formations during cementing operation. Thus, poly (AM-co-AMPS)/GO as a suitable rheology modifier and property enhancer can be applied in oil well cementing.

Improvement in bioavailability of curcumin within the castor‐oil based polyurethane nanocomposite through its conjugation on the surface of graphene oxide nanosheets

AbstractRecently biocompatible polyurethane (PU) films, made from renewable bioactive compounds have been introduced as a feasible option to accelerate wound healing process. In this work, graphene oxide (GO) nanostructures were applied as a practical nanocarrier system to enhance the bioavailability of curcumin within castor‐oil based PU elastomer nanocomposites. Successfully modification of GO nanosheets with curcumin (C‐GO) were confirmed by FT‐IR, XRD, TGA, Raman spectroscopy, and FE‐SEM microscopy techniques. FE‐SEM images demonstrated a good dispersion quality of C‐GO nanosheets in the PU matrix, demonstrating the enhanced bioavailability of curcumin. Based on XRD diffractograms, PU/C‐GO nanocomposite showed a lower crystallinity and microphase‐separation degree compared to blank PU sample. This finding is probably originated from the amphiphilic properties of C‐GO which provides possibility of good interactions with hard and soft domains in PU backbone. Moreover, compared to PU/GO nanocomposite, the surface modification of GO with curcumin increased the tensile strength and Young's modulus of PU/C‐GO nanocomposite to 4.92 and 44.49 MPa, respectively. The in vitro MTT assay revealed a significant viability for L929 fibroblast cells in exposure with PU/C‐GO film. Besides, the results of in vivo wound healing evaluation on the mouse model indicated that the PU/C‐GO sample could accelerate the healing rate by promoting the proliferation and re‐epithelialization of fibroblast cells in the wound site. Thus, it is suggested that the PU/C‐GO nanocomposite film may has a potential and promising application as a wound dressing.

In Situ Grown Tungsten Trioxide Nanoparticles on Graphene Oxide Nanosheet to Regulate Ion Selectivity of Membrane for High Performance Vanadium Redox Flow Battery

AbstractThe application of vanadium redox flow batteries (VRFBs) has encountered challenges because the most commonly used commercial membrane (perfluorinated sulfonic acid, PFSA) has severe vanadium ion permeation, which yields poor stability of the battery. Herein, a PFSA‐based hybrid membrane with a sandwich structure created using a reinforced polytetrafluoroethylene thin layer with hydrophilic nanohybrid fillers is developed. The tungsten trioxide (WO3) nanoparticles are in situ grown on the surface of graphene oxide (GO) nanosheets to overcome the electrostatic effect, and to enhance the hydrophilicity and dispersibility of GO nanosheets, which is embedded in the PFSA matrix to act as a “barrier” to reduce vanadium ions permeation. In addition, these hydrophilic WO3 nanoparticles on GO nanosheets surface serve as proton active sites to facilitate proton transportation. As a result, at 120 cm−2, the cell of the hybrid membrane displays high Coulombic efficiency (over 98.1%) and high energy efficiency (up to 88.9%), better than the commercial Nafion 212 membrane at the same condition. These performances indicate the proposed hybrid membrane is applicable for VRFB application. Also, this design method of the membrane can be extended to other fields including water treatments and fuel cells.

Fe3O4 Nanoparticle-Decorated Graphene Oxide Nanosheets for Magnetic Assembly of Artificial Nacre

Natural nacre, often referred as nature’s armor, has a typical “brick-and-mortar” hierarchical micro-/nanoscale multilayer microstructure and remarkable tensile strength and toughness. The highly ordered multilayer microstructure of nacre provides valuable insights into constructing advanced nanocomposites. Although significant success has been achieved in simulating artificial nacre-mimetic materials on a laboratory scale, it is still difficult to apply on a large scale because of time-consuming sequential depositions. In this study, a rapid and large-scalable magnetic assembly process for the fabrication of the graphene oxide (GO)-based composite film that mimics the structure of nacre was reported. Magnetic GO nanosheets were synthesized by decorating Fe3O4 nanoparticles on the surface of GO nanosheets and then assembled with poly(vinyl alcohol) (PVA) solution to form nacre-mimetic nanocomposites via the magnetic assembly technique. The tensile strength and toughness of the MGO–PVA film can reach 248.0 ± 6.7 MPa and 7.0 ± 0.5 MJ·m–3, which are 5.0 and 4.0 times higher than the pure MGO film, respectively. More interestingly, after in situ reduction by hydroiodic acid, the tensile strength reached as high as 340.0 ± 6.2 MPa. This work offers a rapid process of fabricating strong integration nacre-inspired materials, which shows applications in engineering, aerospace, flexible energy devices, and electromagnetic interference shielding materials.

Intracellular CircRNA imaging and signal amplification strategy based on the graphene oxide-DNA system

CircRNA is a type of covalently closed circular RNA molecule that serves as a potential biomarker for the disease early diagnosis and clinical researches. To achieve living cell imaging of specific circRNA, we developed a novel graphene oxide (GO)-based catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR) signal dual amplification system (GO-CHA-HCR, abbreviated GO-AR) for circ-Foxo3 imaging in living cells. The developed system consists of four types of designed hairpin DNA HP1, HP2, H1, and fluorophore-labeled H2, which are absorbed on the GO nanosheets surface leading to fluorescence quenching. In the presence of circ-Foxo3, the CHA cycle was initiated to form a hybrid chain with split fragments, which triggered the HCR cycle to generate dsDNA nanowires that were then released from GO. This process recovered the quenched fluorescence, realizing two-stage signal amplification. The GO-AR system effectively improved the signal-to-noise ratio compared to the traditional GO-CHA and GO-HCR detection system. The detection limit of circ-Foxo3 was as low as 15 pM with excellent sensitivity and selectivity. In addition, the enzyme-free sensing system was successfully applied in living cell circRNA imaging and serum circRNA detection, indicating its high potential in clinical diagnostics.

Enhancement of the photocurrent and electrochemical properties of the modified nanohybrid composite membrane of cellulose/graphene oxide with magnesium oxide nanoparticle (GO@CMC.MgO) for photocatalytic antifouling and supercapacitors applications

A novel nanohybrid material (NHM) of magnesium oxide nanoparticle (MgO NPs) and modified antifouling membrane surface of graphene oxide nanosheet (GO) and carboxymethylcellulose (CMC) has been created via precipitation and ultrasonication methods, then characterized via various techniques for a novel antifouling membrane for water treatment, and supercapacitor applications for energy applications. The electrochemical properties of nanohybrid material (NHM) have been synthesized successfully by the cyclic voltammetry technique for detecting charge transfer, supercapacitor, and energy storage. Also, the optical properties of NHM antifouling nanomembrane have been detected by zeta potential and UV-spectroscopy apparatus for the following the generation of electrons, charge transfer, and formation of the reactive oxygen species (ROS) for oxidation of the organic materials pollutants for water treatment. The electron transfer of GO@CMC.MgO has been revealed via the photocatalytic process for the degradation of organic and inorganic pollutions. The supercapacitor and energy applications have been detected via the measurements of electrochemical impedance spectroscopy (EIS) by Nyquist plots, the following results have been obtained:-A good electron transfer has been detected with GO@CMC.MgO NHM.-The photocatalytic process with organic compounds pollution has been detected.-The supercapacitor and energy application have been revealed.The Results demonstrated that the fabricated NHM is promising electrode material for supercapacitor applications, energy storage and water treatment.