Surface Of Graphene Nanosheets Research Articles

Multidimensional construction of 1T-MoS2@graphene nanosheets nanocomposites for enhanced electromagnetic wave absorption

The preparation of electromagnetic (EM) wave absorption materials provided with the characteristics of thin matching thickness, broad bandwidth, and mighty absorption intensity is an efficient solution to current EM pollution. Herein, Graphene nanosheets (GN) were firstly fabricated via a facile high-energy ball milling method, subsequently high-purity 1T-MoS2 petals were uniformly anchored on the surface of GN to prepare 1T-MoS2@GN nanocomposites. Plentiful multiple reflection and scattering of EM waves in a distinctive multidimensional structure formed by GN and 1T-MoS2, copious polarization loss consisting of interfacial polarization loss and dipolar polarization loss severally derived from multitudinous heterointerfaces and profuse electric dipoles in 1T-MoS2@GN, and mighty conduction loss originated from plentiful induced current in 1T-MoS2@GN generated via the migration of massive electrons, all of which endowed 1T-MoS2@GN nanocomposites with exceptional EM wave absorption performances. The minimum reflection loss (RLmin) of 1T-MoS2@GN reached –50.14 dB at a thickness of only 2.10 mm, and the effective absorption bandwidth (EAB) was up to 6.72 GHz at an ultra-thin matching thickness of 1.84 mm. Moreover, the radar scattering cross section (RCS) reduction value of 36.18 dB m2 at 0° could be achieved as well, which ulteriorly validated the tremendous potential of 1T-MoS2@GN nanocomposites in practical applications.

Fabrication and Optimization of Primary Batteries Using Ni/Graphene Nanosheet Electrodes

This study aims to investigate the impact of varying the mass ratio of Ni to Graphene Nano Sheets (GNS) and how incorporating GNS affects the performance of a primary battery prototype (Ni/GNS//electrolyte//GNS). The primary battery prototype was developed using both impregnation and alloy methods. Different mass ratios of Ni/GNS to electrolyte to GNS were tested, including ratios of 1:2:1 (A), 2:2:1 (B), 1:2:2 (C), 2:1:2 (D), and 1:1:2 (E). The characterization of GNS, Ni/GNS, and the primary battery prototype involved using X-Ray Diffraction (XRD) and Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX) instruments. A multimeter was employed to measure electrical conductivity, energy density, and power density. A potentiostat/galvanostat was used to measure cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). XRD analysis showed a broad and weak peak at 2θ= 24.32° for GNS, confirming its successful synthesis. Additionally, a peak at 2θ = 43.5° indicated effective deposition of Ni on the GNS surface in Ni/GNS. The SEM-EDX results supported the XRD findings, showing regularly spaced pores and a thin surface layer in GNS. Notably, white spots on the graphene surface in Ni/GNS indicated successful Ni deposition. In terms of electrical conductivity, the highest value was observed in the primary battery prototype for sample D (2:1:2), which measured 1.11 S/cm2. These results were also supported by measurements of energy density and power density in sample D, which achieved the highest values among all samples, with 144,788 Wh/kg and 252,500 W/kg, respectively. Moreover, the CV and EIS measurements remained stable at 0.30 kΩ and 0.88 kΩ, suggesting that GNS could potentially conduct electrons owing to its electrical conductivity.

Thermal conductive nylon 6 composites using hybrid fillers to construct a three‐dimensional thermal conductive network

AbstractThe rapid progress in miniaturization and integration of semiconductor power devices has made heat dissipation a critical concern in the development of high‐performance semiconductor devices, thereby increasing the demands for the heat transfer efficiency of polymer composites. To address this issue, an efficient three‐dimensional (3D) heat conduction network structure is constructed in the polymer matrix by leveraging the mutual reaction of amino and epoxy groups on the surface of the filler treated by coupling during the melt mixing process, this approach leads to an enhancement in the thermal conductivity of the composites. First, the inert surfaces of graphene nanosheets (EX‐G) and carbon fibers (CF) are coated with polydopamine (PDA) to form active sites. Subsequently, the graphene (EX‐G), alumina (Al2O3), and carbon fiber (CF) are treated with an amine coupling agent (KH550) and epoxy coupling agent (KH560), respectively. Notably, at a filler content of 25 wt%, the thermal conductivity (TC) of the composites increases by approximately 282% compared to pure nylon 6. This research contributes novel insights into the field of thermally conductive polymer composites.Highlights The surface of the EX‐G and CF covered by PDA generates active sites. Fillers reduce the interface thermal resistance through chemical bonds. Fillers surface reaction builds a 3D thermal conductive network. 3D network structure can significantly improve the TC of composites. Only 25 wt% of hybrid fillers in a 282% increased TC of composites.

Graphene nanosheet-supported ultrafine RuO2 quantum dots as electrochemical energy materials

Ruthenium oxide (RuO2) shows great promise as an electrode material for supercapacitors, which are energy storage devices that have large power densities. However, RuO2 materials suffer low surface area, poor electrical conductivity and a tendency to aggregate after reactions, limiting their rate capability and cycle stability and can lead to inadequate redox reactions with electrolytes. To address these problems, this work synthesized homogeneous ultrafine-RuO2 quantum dots (QDs) materials with a size of around 2 nm on the surface of graphene nanosheets (GNS) via a facile hydrothermal method. The small size and uniform distribution of RuO2 QDs in the composite electrode material allowed for a high concentration of active adsorption sites for ions in the electrolyte while also facilitating efficient electrochemical redox reactions. The resulting RuO2/GNS composite exhibited a large specific area of 177.34 m2g‐1 and demonstrated an excellent capacitance performance of 1138.5 Fg‐1 at a current density of 0.5 Ag‐1. Additionally, a retention rate of 91.4 % when applying current densities from 0.5 to 10 Ag‐1 and cycling stability with 94.5 % retention after 20000 cycles, demonstrates the occurrence of a rapid and reversible faradaic redox reaction on the electrode surface. The symmetrical supercapacitor configuration with two identical RuO2/GNS electrodes was fabricated and demonstrated a high capacity (309.16 Fg‐1 at a current density of 0.5 Ag‐1) and an outstanding retention rate of 91.2 % at a current density of 10 A g−1). A device operated within a 1.8 V potential window showed high energy density from 126 Whkg‐1 to 139.2 Whkg‐1 and a power density from 440.1 Wkg‐1 to 8494.4 Wkg‐1 at current densities ranging from 0.5 Ag‐1 to 10 Ag‐1, respectively. This ultrafine-RuO2 quantum dots composite is a potentially promising advanced functional electrode material for electrochemical applications beyond supercapacitors and may be suitable for a broader range of energy storage and conversion applications.

3D porous alumina/graphene hybrids prepared by atomic layer deposition and their performance for water treatment

Metal / carbon hybrids have impressive potential of applications in many fields: catalysis, energy conversion and storage, environmental. However, further efforts are needed to achieve a better control of homogeneity of the metal oxide deposit on the carbon surface to provide reliable synthesis approaches of metal / carbon hybrids. In this work, atomic layer deposition is used to prepare 3D porous alumina / reduced graphene oxide hybrid monoliths. We show that atomic layer deposition, even though rarely reported to prepare metal oxide / carbon hybrids, allows a conformal coating onto the graphene nanosheet surface. In-depth advanced characterization have been performed thanks to a coupled approach consisting of the preparation of lamellas of the porous hybrid by means of focused ion beam and their analysis by transmission electron microscopy. A good accessibility of the alumina precursors to the internal surface of the prepared 3D porous carbon monoliths was evidenced. The alumina / graphene hybrid prepared with 50 cycles of ALD deposit has a surface as high as 284 m2/g. As a proof-of-concept for the interest of the designed hybrids, they are tested for the removal of Congo red, a standard organic dye pollutant. 87 and 98 % of Congo red removal were reached at the first and the second step of adsorption proving the good adsorption performance and reusability ability of the de designed hybrid adsorbents. We believe that such multi-porous 3D alumina / graphene macrostructures that offers a favorable accessibility to the adsorption sites open interesting potentialities for pollution remediation applications.

Multi-electron reaction based molybdenum pentasulfide towards high-energy density all-solid-state lithium batteries

All-solid-state lithium batteries based on multiple electron reaction cathode can exhibit high reversible specific capacity, and thus realizing high energy density. Improving electronic/ionic conductivities and alleviating volume changes are of great significance for achieving high performance all-solid-state batteries. In this work, amorphous MoS5 nanoparticles are homogeneously anchored on the surface of graphene nanosheets by a hydrothermal method, thereby improving electronic conductivity and reducing volume changes of active material. Then, Li7P3S11 nanoparticles are coated on MoS5@10 %graphene via an in situ liquid-phase method, resulting in intimate interface contact between active material and electrolyte. The resultant all-solid-state lithium batteries based on MoS5@10 %graphene-15 %Li7P3S11 nanocomposite cathodes exhibit a high initial discharge capacity of 1030.1 mAh/g at 0.1 A/g and a reversible specific capacity of 570.7 mAh/g at 0.5 A/g after 500 cycles. Moreover, the obtained all-solid-state lithium battery using MoS5@10 %graphene-15 %Li7P3S11 cathode displays a high energy density of 493.0 Wh kg−1 at 0.1 A/g and a high power density of 470.3 W kg−1 at 1.0 A/g based on the total mass of cathode layer. The unique structure endows excellent electronic/ionic conductivities of active material and intimate interface contact in the cathode layer, enabling a stable all-solid-state lithium battery with good cycling stability and high energy density.

Enhanced Na-ion storage via creating smooth ions transportation pathways in a modified heterostructure

Sodium-ion batteries (SIBs) have drawn evolutionary attention due to the urgent requirements for renewable energy storage. Unfortunately, the cycle stability and rate capability of promising SnO2 materials are far from satisfactory. Herein, enhanced Na-ion storage via creating smooth ion transportation pathways in a modified heterostructure has been originally demonstrated. The tuned composite of uniformly dispersed SnO2 particles anchored on the surface of graphene nanosheets was prepared via a facile hydrothermal treatment with the help of iodine. Inspiringly, an anticipated Na-ion storage can be successfully achieved, with reversible Na-ion storage of 486.1 mA h g−1 at 50 mA g−1 and rate capability of 343.8 mA h g−1 even at 800 mA g−1. The exceptional electrochemical property profited from the synergistic effect of the heterostructure with plentiful ion transportation pathways for fast Na-ion diffusion. This work opens a practical opportunity for the design of next-generation rechargeable batteries in energy storage.

Distribution model of Iron (Fe) on Fe/Graphene Nano Sheets

In this paper, we report about the distribution model of Iron (Fe) atoms on Graphene Nano Sheets (GNS). The purpose of this research is to evaluate the performance of Fe/GNS in terms of the distribution of Fe atoms on the graphene surface. GNS and Fe/GNS were prepared with modified Hummer's and impregnation methods, respectively. We found that the morphology of graphite is different compare to GNS where GNS has thin layers and no stacking sheets (Scanning Electron Microscope (SEM) data) and it contains majority Carbon (C) element (more than 90 wt%) (EDX data). The X-Ray Diffraction (XRD) data of GNS shows the appearance weak and broad peak on 2θ = 26.6o indicating GNS was formed, and the sharp peaks on 2θ = 43.84o prove that Fe atoms are well deposited on GNS (XRD data). Both SEM and XRD data prove GNS produced and Fe deposited on GNS. Further, we propose the distribution model of Fe atoms on GNS surfaces based on three steps. The first step is the Fe precursor react with GNS to produce Fe ions. The second step is Fe ions reduce while being deposited on GNS surfaces, generating Fe clusters. Finally, Fe clusters migrate on the surfaces of GNS to form Fe particles. The smallest Fe crystal size in Fe/GNS is at 3.81% Fe (1.5009 nm) and distributed into GNS. Based on those data, GNS was found to affect the properties of Fe metal.

Graphene-based resistant sensor decorated with Mn, Co, Cu for nitric oxide detection: Langmuir adsorption & DFT method

PurposeThe purpose of this paper is to investigate the ability of transition metals (TMs) of iron-, nickel- and zinc-doped graphene nanosheet for adsorption of toxic gas of nitric oxide (NO). The results of this paper have provided a favorable understanding of the interaction between TM-doped graphene nanosheet and NO molecule.Design/methodology/approachA high performance of TM-doped graphene nanosheet as a gas sensor is demonstrated by modeling the material’s transport characteristics by means of the Langmuir adsorption and three-layered ONIOM/ density functional theory method. The Langmuir adsorption model has been done with a three-layered ONIOM using CAM-B3LYP functional and LANL2DZ and 6–311G (d, p) basis sets by Gaussian 16 revision C.01 program towards the formation of of NO→TM(Mn, Co, Cu)-doped on the Gr nanosheet.FindingsThe changes of charge density for Langmuir adsorption of NO on Mn-, Co- and Cu-doped graphene nanosheet orderly have been achieved as: ΔQCo-doped = +0.309 >> ΔQMn-doped = −0.074 > ΔQCu-doped = −0.051. Therefore, the number of changes of charge density have concluded a more remarkable charge transfer for Mn-doped graphene nanosheet. However, based on nuclear magnetic resonance spectroscopy, the sharp peaks around Cu doped on the surface of graphene nanosheet and C19 close to junction of N2 and Co17 have been observed. In addition, Cu-doped graphene sheet has a large effect on bond orbitals of C8–Cu 17, C15–Cu 17 and C16–Cu17 in the adsorption of NO on the Cu-doped/Gr which has shown the maximum occupancy. The amounts of through IR computations based on polarizability have exhibited that has indicated the most energy gap because of charge density transfer from the nitrogen atom in NO to Mn-doped graphene nanosheet, though Originality/valueThis research aims to explore the adsorption of hazardous pollutant gas of “NO” by using carbon nanostructure doped by “TM” of iron, nickel and zinc to evaluate the effectiveness of adsorption parameters of various TM-doped graphene nanosheets.

Carbon anode of intercalation capacitive coupling mechanism enabling long term potassium ion capacitors at low temperature

Low temperature comprehensive performance of the dominating lithium ion batteries (LIBs) is a matter of increasing concern. In this work, we screen typical carbon anodes with different structural features such as interlayer spacing, degree of graphitization, porosity, and specific surface area, for sustainable potassium ion capacitors (PICs) at −20 °C. Graphene nanosheet (GN) exhibits much better K+ storage performance over the other carbon materials including graphite, activated carbon, and hard carbon, which is ascribed to the synergistic effects of high conductivity, enlarged interlayer spacing, moderate specific surface area, mesopore structure, and short K+ diffusion path. This screening guides a design direction of carbon anode for K+ storage device at low temperature. Meanwhile, the electrolyte additive of Cs cation could be preferably reduced at the surface of GN during the potassiation, which enables a thin and robust solid electrolyte interphase (SEI) layer and effectively suppresses the co-intercalation induced GN exfoliation and electrolyte decomposition, giving rise to improved cyclic stability at −20 °C. The assembled PICs based on the GN anode and optimized electrolyte enable a comprehensive low temperature performance, especially long-term stability (2000 cycles) over batteries, demonstrating a reliable electrical energy storage device at low temperature.

A novel Ti(OH)4/graphene flame retardant towards reducing fire hazards of phenolic resin

Ti(OH) 4 /graphene was synthesized by hydrolysis of titanium tetrachloride into titanium hydroxide and precipitation on the surface of graphene nanosheets, and was incorporated into phenolic resin to prepare phenolic composites using hexamethylenetetramine as a curing agent. After that, the effects of Ti(OH) 4 /graphene on the thermal stability, flame retardancy, and smoke suppression properties of phenolic matrix were studied. When the content of Ti(OH) 4 /graphene was 5 wt.%, phenolic composites passed the UL-94 V-0 rating with a limiting oxygen index (LOI) of 28.6%, and the residual char at 800 °C was 56.83 wt.%. Cone calorimeter tests demonstrated that the peak heat release rate (pHRR), total heat release (THR) and total smoke production (TSP) of phenolic composite contained 10 wt.% Ti(OH) 4 /graphene were 86.3 kW/m 2 , 30.74 MJ/m 2 and 1.8 m 2 , respectively, which were reduced by 41.85%, 24.82%, and 30.78% compared with pure phenolic resin. And the smoke density test also showed that the smoke density of phenolic composite contained 10 wt.% Ti(OH) 4 /graphene had a 51.89% reduction. These data indicated that Ti(OH) 4 /graphene can effectively improve the flame retardant and smoke suppression performance. Moreover, the char residue after combustion is investigated using SEM, FTIR, XRD and Raman technologies, and the results demonstrated that Ti(OH) 4 /graphene could greatly promote the formation of a continuous and dense char residue layer in phenolic composites. Py-GC/MS results further revealed that the degradation products contents of phenolic resins were decreased by incorporating Ti(OH) 4 /graphene. Therefore, the flame retardancy of phenolic composite is significantly improved through the mechanism of endothermic effect, coverage effect, and dilution effect of combustible gas. This feasible method can provide new insights for reducing fire hazards of phenolic resin. • Ti(OH) 4 /graphene was prepared and incorporated into phenolic resin as an additive flame retardant. • Phenolic composites containing only 5 wt.% Ti(OH) 4 /graphene passed UL-94 V-0 rating. • Ti(OH) 4 /graphene significantly improved flame retardancy performances of phenolic composites. • The flame retardant mechanism of Ti(OH) 4 /graphene in phenolic composites was investigated.

Mass ratio-dependently tunable enhancement of the optical nonlinearities of SnO2/RGO composites

The composite of graphene and semiconductor nanoparticles has attracted increasing interest in the search for novel nonlinear optical materials. Herein, composites of reduced graphene oxide (RGO) and SnO2 nanoparticles with different mass ratios were synthesized via a facile hydrothermal method. The structural morphology and basic physical properties of the SnO2/RGO composites were characterized using TEM, SEM, XRD, Raman, XPS and UV–Vis spectra, indicating that SnO2 nanoparticles were uniformly anchored on the surface of graphene nanosheets through covalent and partial-ionic bonds. The third-order optical nonlinearities of the composites were studied for the first time by the Z-scan technique using a picosecond laser at 532 nm. It was found that the composites demonstrated saturable absorption and positive nonlinear refraction properties, and both were significantly enhanced compared with pure SnO2 nanoparticles and RGO nanosheets, and the enhancement was tunable with the variation of SnO2:GO mass ratio. The maximum saturable absorption coefficient and the third-order susceptibility of the as-prepared SnO2/RGO composites were obtained to be −2.93×10–11 m W−1 and 2.25 × 10–11 esu, respectively. The maximum saturable absorption modulation depth obtained was 10% with the corresponding saturation light intensity of 0.3 GW cm−2. Moreover, the optimised third-order susceptibility of SnO2/RGO was found much greater than many other materials ever studied. Several involved factors contributing to the nonlinearities were discussed. The results propose that the third-order optical nonlinearities of SnO2/RGO and other similarly structured composites can be potentially tuned to meet certain application requirements of nonlinear optical devices by controlling the mass ratio of semiconductor to graphene.

Synthesis of MnO2/Graphene Nanocomposites using Plasma Electrolysis Method for Photocatalytic Degradation of Methyl Orange Dye in Water

This report presented an effective way to synthesize MnO2/graphene nanocomposites using the plasma electrolysis method for photocatalytic degradation of methyl orange dye in water. The morphology, structure, and chemical composition of MnO2/graphene nanocomposites materials were investigated through scanning electron microscopy (SEM), Raman spectra, and Fourier-transform infrared (FTIR) spectroscopy, respectively. SEM results showed that MnO2 nanoparticles with particle sizes of 30-50 nm were attached uniformly on the surface of graphene nanosheets. The photodegradation activity was performed under UV-visible irradiation to evaluate the potential application of MnO2/graphene nanocomposites.

Microwave absorption and dielectric behavior of lead sulfide – graphene composite nanostructure embedded polyvinylidinedilfuoride thin films

A lightweight and flexible microwave absorbing composite of polyvinyledine difluoride (PVDF) was fabricated by loading PbS nanocubes embedded Graphene hybrid nanostructures into the PVDF matrix. The PbS embedded graphene nanosheets (PbS/GNs) are synthesized by hydrothermal technique. The PXRD pattern of the PbS, GNS and PbS/GNS suggested face-centered cubic structured PbS loaded GNS nanosheets. FE-SEM images of the graphene-bound lead sulfide octahedral nanocubes are found to have a size of 100 nm and are unvaryingly distributed on the surface of graphene nanosheets. HRTEM image of graphene surface image showing sheet-like structure is embedded with PbS nanocrystals. The PbS/GNs in PVDF matrix were found to exhibit enhanced dielectric constant, reduction in resistivity, and electrical conductivity. The high dielectric constant was exhibited by the 4% GNs dispersed PVDF with a value of 3.7x105 and 6% GNs/PbS dispersed PVDF showed 3.5 x105 at 1 MHz. The composite PbS/GNs into PVDF exhibit the maximum reflection loss dips in frequency band X for the PbS/Gra/PVDF samples. It is apparent that there are three absorption peaks in the region of 9–12 GHz in which the absorption of −6.9 dB is observed at 10 GHz.

Effect and mechanism of doped graphene nanosheets on phase transition properties of sodium nitrate

Molten salt is regarded as one of most promising candidates for solar energy storage due to possessing stable properties and large energy storage densities. However, the intrinsically low thermal conductivity of molten salt has become a bottleneck for rapid heat storage and transport. The addition of nanoparticles is generally considered to be a most effective way to improve the thermal conductivity of molten salt phase change materials (PCMs), while the phase change enthalpies of the nanocomposite phase change materials usually show two opposite trends of enhancement or decrement. Furthermore, the reason for the abnormal change of phase change enthalpy has not been clear in the literature so far, so the mechanism of change needs to be further explored. In this work, graphene nanosheets (GNS)@NaNO<sub>3</sub> (sodium nitrate) nanocomposite phase change materials are prepared by the hydration ultrasonic method. The materials are characterized by scanning electron microscope, and the phase change characteristics are measured using differential scanning calorimeter. Molecular dynamics simulation is carried out to explain the mechanism for the formation of the NaNO<sub>3</sub> dense layer and the non-collateral decrease of the enthalpy from the microscopic level. With the increase of GNS mass fraction, the melting point of the GNS@NaNO<sub>3</sub> composite phase change material decreases slightly while the phase change enthalpy decreases significantly with a non-colligative trend. A 13.81% decrease of the theoretical phase change enthalpy is observed with a GNS doping ratio of 1.5%. The NaNO<sub>3</sub> clusters observed on the surface of GNS are considered to have not melted, thereby resulting in a reduction in the phase change enthalpy. The mechanism is further investigated by molecular dynamics simulation, showing that the strong van der Waals attraction between GNS and NaNO<sub>3</sub> leads the 2–4 Å-thick NaNO<sub>3</sub> dense layer to form in the vicinity of GNS. With the increase of GNS mass fraction, the centroid equivalent distance between the dense layer and GNS gradually increases, which leads their mutual attraction to first increase and then weaken. When GNS mass fraction is 1.5%, the centroid equivalent distance reaches the position closest to the potential well, leading to a strongest mutual attraction. In other words, the phase change enthalpy decreases most obviously at this mass fraction. Thus, some conclusions can be drawn as follows. The type of interaction between molten salt and nano-enhancers and the position of the potential well are the fundamental reasons for the thickness of molten salt dense layer and the reduction of phase change enthalpy. The calculation of the interaction energy can be used to guide the selection of the mass fraction of the nano-enhancers, so as to avoid the loss of core material cluster and phase change enthalpy caused by the introduction of the nano-enhancers to a greatest extent. The preparation cost of the composite phase change material can also be reduced to a certain extent.

Synthesis and Third-Order Nonlinear Synergistic Effect of ZrO2/RGO Composites.

Tuning the third-order nonlinear properties of graphene by hybrid method is of great significance in nonlinear optics research. ZrO2/reduced graphene oxide (RGO) composites with different ZrO2 concentrations were prepared by a simple hydrothermal method. The morphology and structure show that ZrO2 nanoparticles were uniformly dispersed on the surface of graphene nanosheets. The nonlinear optical (NLO) characteristics of composites with different ZrO2 concentrations were studied by the Z-scan technique of 532 nm picosecond pulsed laser. The results showed that ZrO2/RGO composites had saturated absorption and positive nonlinear refraction characteristics. Meanwhile, the third-order nonlinear susceptibility of the ZrO2/RGO composite with a 4:1 mass ratio of ZrO2 to graphene oxide could reach 23.23 × 10−12 esu, which increased tenfold compared to RGO, and the nonlinear modulation depth reached 11.22%. Therefore, the NLO characteristics could be effectively adjusted by controlling the concentration of ZrO2, which lays a foundation for further research on the application of ZrO2/RGO composites in NLO devices.

Defective graphene nanosheets for drinking water purification: Adsorption mechanism, performance, and recovery

Defect-rich graphene oxide (dGO) was used as sorbent for organic contaminants of emerging concern in tap water, including drugs and dyes, and the performance compared to those of lower-defects graphene types. The role of holes and carbonyl- carboxylic groups on graphene nanosheets surface on the adsorption mechanism and efficiency was investigated. dGO showed enhanced adsorption capacity toward two fluoroquinolone antibiotics (ofloxacin, OFLOX, and ciprofloxacin, CIPRO) in tap water with a maximum capacity of 650 mg/g, compared to 204 mg/g for Hummers derived commercial GO (hGO) and 125 mg/g for less defected Brodie derived GO (bGO) for OFLOX. The role of defects on the selective adsorption of OFLOX was also modelled by MD simulations, highlighting a mechanism mainly driven by the shape complementarity between the graphene holes and the molecules. Adsorption isotherms revealed different adsorption model for dGO, with a Langmuir fitting for dGO and BET fitting for all the other investigated samples. The maximum adsorption capacity of dGO for OFLOX was about six times higher than that of Granular Activated Carbon (95 mg/g), the industrial adsorption standard technology. Finally, it was also demonstrated that dGO can be recovered from treated water by ultrafiltration, this preventing secondary contamination risks and enabling safe use of graphene nanosheets for water purification.

A rapid nanobiosensing platform based on herceptin-conjugated graphene for ultrasensitive detection of circulating tumor cells in early breast cancer

AbstractIn this paper, we use a simple and cheap approach for the synthesis of herceptin-conjugated graphene biosensor to detect the HER2-positive breast cancer cells. The bifunctional graphene-herceptin nanosheets are prepared from graphite by a simple ultrasonic-mediated technique. The prepared protein-mediated graphene is fully characterized. The results show the exfoliation of graphene layers in herceptin solution. Moreover, herceptin is effectively conjugated into the surface of graphene nanosheets. The synthesized herceptin-conjugated graphene is applied for breast cancer detection. The linear range of this biosensor is 1–80 cells, which is significant. The biosensor shows an excellent selectivity performance for detection of HER2-positive cancer cells. Likewise, the stability and functionality of the biosensor is about 40 days. Based on the results, this device is a promising candidate for rapid and selective detection of cancer cells.

Graphene/chitosan/Ag+- doped hydroxyapatite triple composite fiber coatings on new generation hybrid titanium composite by electrospinning

In this work, The hybrid hydroxyapatite (HaP), chitosan (CH) and graphene nanosheets (GNS) mixtures were applied by electrospinning on the surface of GNS and Si3N4 (SN) binary powder reinforced hybrid titanium (Ti) metal composites surface to improve composite biosurface functionallity. The surfaces of coated materials were characterized and antibacterial tests were carried on for their suitability in the industry by performing artificial body fluid tests. The hybrid nano fiber coatings formed a homogeneous structure on the composite. According to bioactivity tests and microstructure analysis, it was seen that HaP, which has the best results in the change of pH (pH= 11.80) values. The lowest mass change (0.0005 g) was observed on the 10th day of pure titanium. The highest mass change (0.0210 g) was obtained as on the HaP coated hybrid titanium composite. According to the antibacterial test result the hybrid nanofiber containing silver (Ag+) doped HaP on Ti composites showed the best antibacterial property aganist the E.coli. The fabricated electrospin coated hybrid composites can be a potantial candidate for dental, orthopedic implant applications and tissue engineering.

Supercritical CO2 Assisted Solvothermal Preparation of CoO/Graphene Nanocomposites for High Performance Lithium-Ion Batteries.

Supercritical CO2 (scCO2) is often used to prepare graphene/metal oxide nanocomposite anodes for high performance lithium-ion batteries (LIBs) by the assisted solvothermal method due to its low viscosity, high diffusion, zero surface tension and good surface wettability. However, the formation mechanism of metal oxides and the combination mechanism between metal oxides and graphene in this system are superficial. In this work, a cobalt monoxide/graphene (CoO/G) nanocomposite is fabricated via the scCO2 assisted solvothermal method followed by thermal treatment. We elucidate the mechanism that amorphous intermediates obtain by the scCO2 assisted solvothermal method, and then ultrafine CoO nanoparticles are crystallized during the heat treatment. In addition, scCO2 can promote CoO to be tightly fixed on the surface of graphene nanosheets by interfacial chemical bonds, which can effectively improve its cycle stability and rate performance. As expected, the CoO/G composites exhibit higher specific capacity (961 mAh g−1 at 100 mA g−1), excellent cyclic stability and rate capability (617 mAh g−1 after 500 cycles at 1000 mA g−1) when applied as an anode of LIB.