Graphene Hybrid Nanosheets Research Articles

Preparation and sodium storage properties of CoFe2O4 composite S N co-doped RGO

The application value of iron-base binary oxide in sodium-ion batteries has been widely concerned by researchers, and CoFe2O4 has a better development prospect because of its cost efficiency. However, the CoFe2O4 will produce volume expansion during the reaction, resulting in the collapse of the material structure. This paper created the ground-breaking CFO/SNRGO nanocomposite structure by using a microwave approach. This intricate arrangement entails CoFe2O4 nanoparticles firmly adhering to S and N co-doped graphene hybrid nanosheets. The prepared CFO/SNRGO nanocomposite showcased remarkable electrochemical capabilities. Through the uniform integration of CoFe2O4 nanoparticles onto the SNRGO hybrid nanosheets, we managed to minimize the stacking between SNRGO nanosheets and reduce the size of the CoFe2O4 nanoparticles. Additionally, the SNRGO serves as a buffer layer, allowing it to adjust to variations in volume and stop the CoFe2O4 nanoparticles from collapsing while Na+ is being embedded or removed. This cooperative amalgamation of SNRGO and CoFe2O4 contributes to the outstanding electrochemical performance observed in the CFO/SNRGO nanocomposites. After 200 cycles at an electrical concentration of 0.05 A g−1, the CFO/SNRGO nanotechnology demonstrated a notable 357.3 mAh g−1 bidirectional ability. and sustained excellent rate performance. Even when subjected to an increased electrical concentration of 1.5 A g−1, the reversible capacity remained steady at 174 mAh g−1. These impressive outcomes are due to the robust coupling between the CoFe2O4 nanoparticles and SNRGO within the nanocomposites.

Preparation and sodium storage properties of Ni-CoFe2O4/Reduced graphene oxide

The Ni-doped CoFe2O4 graphene composites (Ni-CFO/RGO) have been successfully prepared using the microwave-assisted method. The substance is a novel nanocomposite structure in which CoFe2O4 nanoparticles are tightly and uniformly attached to graphene hybrid nanosheets. The synergistic effect of Ni doping and CoFe2O4 can reduce the volume expansion of CoFe2O4 in the reaction process and inhibit the stacking of graphene. Because the Ni-CFO/RGO composite is structurally stable during the electrochemical reaction, it has a good theoretical capacity. Excellent carbon composite can further enhance the electron transport performance and structural stability of the material, thereby improving the electrochemical performance and cycle life of the material. Doping Ni2+ into metal oxides can not only form oxygen vacancies, and improve the transport capacity of sodium ions, but also broaden the electron transport channel. In addition, the catalyst can form a composite structure with metal oxide, which can effectively inhibit its volume expansion. At the same time, reacting with carbon materials, can also effectively reduce the accumulation of carbon, thereby reducing its resistance. After 200 cycles at a current density of 0.05 A g−1, it can provide a high sodium storage capacity of 380.6 mAh g−1, which still keeps 203.4 mAh g−1 at 1.5 A g−1.

Research on Tunable SPR Sensors Based on WS2 and Graphene Hybrid Nanosheets

A prismatic excitation-based affinity biosensor consisting of the prism (BK7), WS2/graphene hybrid nanosheets, and silver (Ag) as the active metal for the surface plasmon resonance is proposed in this present research. The introduction of the transition metal WS2/graphene layer protected the silver substrate and enhanced the adsorption of biomolecules, which facilitated the quality and performance of detection. Here, we improved the detection structure by focusing on the metallic materials, graphene and WS2 film layers, and the thickness of the measured medium on the sensing effect. The results show that the silver film had a more desirable resonance effect, and the design of the symmetric detection structure produced a double resonance peak, and it provides a reference for distributed sensing. Changing the thickness of the detection medium can dynamically adjust the wave vector matching conditions, which gives the sensor a certain tunability. In the bilayer WS2 and monolayer graphene (W = 2, G = 1) configuration, the sensitivity was up to 224 deg/RIU with a quality factor of 96.97 RIU−1, which has potential for clinical analytic and biochemical detecting applications.

Thermally Conductive and Electrically Insulated Silicone Rubber Composites Incorporated with Boron Nitride-Multilayer Graphene Hybrid Nanofiller.

Thermally conductive and electrically insulating composites are important for the thermal management of new generation integrated and miniaturized electronic devices. A practical and eco−friendly electrostatic self−assembly method was developed to prepare boron nitride−multilayer graphene (BN−MG) hybrid nanosheets. Then, BN−MG was filled into silicone rubber (SR) to fabricate BN−MG/SR composites. Compared with MG/SR composites with the same filler loadings, BN−MG/SR composites exhibit dramatically enhanced electrical insulation properties while still maintaining excellent thermal conductivity. The BN−MG/SR with 10 wt.% filler loading shows a thermal conductivity of 0.69 W·m−1·K−1, which is 475% higher than that of SR (0.12 W·m−1·K−1) and only 9.2% lower than that of MG/SR (0.76 W·m−1·K−1). More importantly, owing to the electron blocking effect of BN, the electron transport among MG sheets is greatly decreased, thus contributing to the high−volume resistivity of 4 × 1011 Ω cm for BN−MG/SR (10 wt.%), which is fourorders higher than that of MG/SR (2 × 107 Ω·cm). The development of BN−MG/SR composites with synergetic properties of high thermal conductivity and satisfactory electrical insulation is supposed to be a promising candidate for practical application in the electronic packaging field.

Fabrication of nitrogen-doped porous graphene hybrid nanosheets from metal–organic frameworks for lithium-ion batteries

To achieve a good electrochemical performance of lithium-ion batteries (LIBs), the design and optimization of the anode is a key issue. Herein, the fabrication of nitrogen-doped porous graphene hybrid nanosheets (denoted as N-PGNS) is proposed via a simple functional group-induced growth of zeolitic imidazolate framework (ZIF-8) on graphene oxides (GO) followed by a one-step pyrolysis strategy. Detailed characterizations reveal that the N-doped porous carbon derived from ZIF-8 is homogeneously anchored on graphene, and can provide high electroactivity and numerous diffusion channels for fast Li+ transport. Meanwhile, the incorporation of graphene as a conductive framework and supporting substrate can accelerate the transfer of electrons. Taking advantage of the synergistic role between the graphene framework and N-doped porous carbon, the N-PGNS exhibits a stable reversible specific capacity of 741.8 mA h g–1 as the anode for LIBs, which is notably higher than that of the N-doped porous carbon obtained directly by pyrolysis of ZIF-8. Furthermore, the N-PGNS electrodes also show superior electrochemical stability with an initial capacity of 90.38% over 1000 cycles at 5 A g–1. The current strategy, which can control and adjust the growth of ZIF-8 via the inducing effect of GO, provides a promising solution to construct graphene hybrid nanosheets for high-performance LIBs.

Synergistic strengthening effect of alumina anchored graphene nanosheets hybrid structure in aluminum matrix composites

The microstructure design of graphene based reinforcement is an effective route to obtain graphene/aluminum composites with good mechanical properties. In this study, alumina anchored on graphene nanosheets hybrid (Al2O3@GNS) was in situ synthesized by a sodium chloride template-assisted high-temperature calcination strategy. Al2O3@GNS was used as a reinforcement to fabricate aluminum matrix composites (Al2O3@GNS/Al) by flake powder metallurgy (FPM) route. It was found that Al2O3@GNS was homogenously distributed and a relatively obvious synergistic strengthening effect was acquired by employing Al2O3@GNS as reinforcement of the composites. ∼1.0 vol%-Al2O3@GNS/Al composite obtained the maximum tensile strength of 359 MPa, an ∼131.6% improvement superior to pure Al. The strengthening efficiency of Al2O3@GNS is higher than those reinforced by individual GNS, Al2O3 or its simple mixture. An elongation of 11.2% was achieved in the ∼ 1.0 vol%-Al2O3@GNS/Al composite, exhibiting a favorable strength-ductility synergy. The synergistic strengthening effect was attributed to the formation of an interlocked network of Al2O3@GNS, which was beneficial to improve the load transfer efficiency from the matrix to reinforcement in the composites.

Interactions Between Hemin-Binding DNA Aptamers and Hemin–Graphene Nanosheets: Reduced Affinity but Unperturbed Catalytic Activity

We demonstrate herein that hemin–graphene hybrid nanosheets (H–GNs) can differentiate hemin-binding DNA aptamers (i.e., guanine-rich DNA sequences that form G-quadruplex structures upon binding hemin) and nonspecific single-stranded oligonucleotides colorimetrically. By exploiting the tendency of the H–GNS to aggregate under high ionic strength and their inherent catalytic activities, excess H–GNS were removed and the amount of H–GNs remaining in the supernatant was quantified. Subsequently, the binding affinity of hemin-binding DNA aptamers to the H–GNS was determined upon titration with the DNA. With the conformity of the experimental data to the Langmuir adsorption isotherm, hemin is hypothesized to be sandwiched between the G-quadruplex DNA and graphene forming a ternary complex as a result of the specific binding of the aptamer with the H–GNS. The binding affinity of the aptamer is not as strong as that of hemin/G-quadruplex in solution, which is attributed to electronic effects imparted by the graphene surface. The catalytic activity of the resulting complex, however, was confirmed to be higher than that of H–GNs alone.

Insights into the electrochemical capacitor performance of transition metal-vertical graphene nanosheet hybrid electrodes.

Vertical graphene nanosheets (VGN) are envisioned as supercapacitor (SC) electrode materials due to their distinct geometry and remarkable properties. Of late, the hybrid structures of graphene-transition metal (TM) or oxides were found to exhibit enhanced charge storage capacity. Herein, we report the charge storage performance of VGN-transition metal nanoparticle (Au, Ag, Cu, and Ni) hybrid electrodes. Amongst them, Ni-decorated VGN exhibited the highest enhancement, up to 3.04 mF cm-2 (121.6 F g-1) compared to 0.16 mF cm-2 (6.4 F g-1) for as-grown VGN. Further, this was corroborated by the improved electrical as well as ionic conductivity of the metal-decorated VGN structures. Additionally, the presence of metal-oxygen-carbon bonding ensured a contribution of pseudocapacitance. Ab initio calculations elucidated the extent as well as the nature of charge (e-) transfer in TM nanoparticle-VGN hybrid structures. These findings are well corroborated with the charge storage performance. A combined effect from charge transfer and pseudocapacitance on the charge storage performance of TM nanoparticle-VGN hybrid electrodes is demonstrated. A symmetric coin-cell supercapacitor device using Ni/VGN electrodes was fabricated and the sustained performance tested over 10 000 charge-discharge cycles.

Free-standing, flexible β-Ni(OH) 2 /electrochemically-exfoliated graphene film electrode for efficient oxygen evolution

Abstract The oxidation of water into molecular oxygen (oxygen evolution reaction, OER) is a pivotal reaction in many energy conversion devices. The high cost of IrO 2 , however, seriously hinder its large-scale applications in water oxidation. Here, we have at first reported a free-standing and flexible film electrode consisting of 2D β-Ni(OH) 2 /electrochemically-exfoliated graphene hybrid nanosheets (NiG-2), which is synthesized by a solvothermal reaction and an assembly process. The as-obtained NiG-2 film electrode exhibited an excellent electrocatalytic OER activity with an extremely low OER onset overpotential of ∼250 mV in a 1 M KOH aqueous solution, which is lower than these of the commercial Ir/C (370 mV at 10 mA cm −2 ) catalyst.

Preparation of MoS2‐graphene Hybrid Nanosheets and Simultaneously Electrochemical Determination of Levodopa and Uric Acid

AbstractMoS2 nanoflakes were prepared by exfoliating commercial MoS2 powders with the assistance of ultrasound and graphene foam was synthesized by chemical vapor deposition using nickel foam as the template. MoS2‐graphene hybrid nanosheets were developed through the combination of MoS2 nanoflakes and graphene nanosheets by ultrasonic dispersion. The hybrid nanosheets were sprayed onto the ITO coated glass, which acts as an electrode for the simultaneously electrochemical determination of levodopa and uric acid. The MoS2‐graphene hybrid nanosheets were characterized by scanning electron microscopy, X‐ray diffraction and Raman spectroscopy. The results show that the hybrid nanosheets are composed of MoS2 and graphene with a sheet‐like morphology. The sensitivity of the electrode for levodopa and uric acid is 0.36 μA μM−1 and 0.39 μA μM−1, respectively. The electrode also shows low limit of detection, good selectivity, reproducibility and stability. And it is potential for use in clinical research.

Supercapacitors: 3D Porous Nanoarchitectures Derived from SnS/S‐Doped Graphene Hybrid Nanosheets for Flexible All‐Solid‐State Supercapacitors (Small 12/2017)

Supercapacitors: 3D Porous Nanoarchitectures Derived from SnS/S‐Doped Graphene Hybrid Nanosheets for Flexible All‐Solid‐State Supercapacitors (Small 12/2017)

Self-assembly of novel hierarchical flowers-like Sn3O4 decorated on 2D graphene nanosheets hybrid as high-performance anode materials for LIBs

Novel hierarchical flower-like Sn3O4 assembled by thin Sn3O4 nanosheets, as a kind of mixed-valence tin oxide, decorated on two-dimensional graphene nanosheets has been synthesized via a hydrothermal route and a step solution deoxidization technique. More importantly, as the anode materials for lithium ion batteries, the flower-like Sn3O4/graphene composite has not been investigated in detail. Noticeably, the nanosheets stemming from flower-like Sn3O4 and graphene have been linked together to form a specials three dimensional structure, possessing high active surface area and large enough inner spaces, which is benefit to the diffusion of liquid electrolyte into the electrode materials. In addition, the special structure could provide sufficient free volume to buffer the volume expansion appeared in the process of discharging and charging. The as-prepared flowers-like Sn3O4/graphene displayed excellent electrochemical performance with high capacity and good cycling stability as anode materials for lithium ion batteries. The discharge capacity is 1727mAh/g in the first cycle at the current density of 60mA/g. The obtained reversible capacity is 631mAh/g with a coulomb efficiency of 97.04% after 50 cycles. With its better electrochemical properties, the as-prepared flowers-like Sn3O4/graphene has the potential to be the next generation materials as an environmentally benign, abundant, cheap anode materials for lithium ion batteries.

3D Porous Nanoarchitectures Derived from SnS/S-Doped Graphene Hybrid Nanosheets for Flexible All-Solid-State Supercapacitors.

3D porous nanoarchitectures derived from SnS/S-doped graphene hybrid nanosheets are successfully prepared by controllable thermal conversion of oleylamine-capped mixed-phase SnS2 -SnS nanodisks precursors, and employed as electroactive material to fabricate flexible, symmetric, all-solid-state supercapacitors. The fabricated solid devices exhibit very high areal specific capacitance (2.98 mF cm-2 ), good cycling stability (99% for 10 000 cycles), excellent flexibility, and desirable mechanical stability.

Bimetallic PtAg alloyed nanoparticles and 3-D mesoporous graphene nanosheet hybrid architectures for advanced oxygen reduction reaction electrocatalysts

Novel hybrid architectures made up of ultrafine and uniform AgPt alloyed nanoparticles and 3-D conductive networks of mesoporous graphene nanosheets are first synthesized for advanced ORR electrocatalysts.

A High-Performance Lithium-Ion Capacitor Based on 2D Nanosheet Materials.

Lithium-ion capacitors (LICs) are promising electrical energy storage systems for mid-to-large-scale applications due to the high energy and large power output without sacrificing long cycle stability. However, due to the different energy storage mechanisms between anode and cathode, the energy densities of LICs often degrade noticeably at high power density, because of the sluggish kinetics limitation at the battery-type anode side. Herein, a high-performance LIC by well-defined ZnMn2 O4 -graphene hybrid nanosheets anode and N-doped carbon nanosheets cathode is presented. The 2D nanomaterials offer high specific surface areas in favor of a fast ion transport and storage with shortened ion diffusion length, enabling fast charge and discharge. The fabricated LIC delivers a high specific energy of 202.8 Wh kg-1 at specific power of 180 W kg-1 , and the specific energy remains 98 Wh kg-1 even when the specific power achieves as high as 21 kW kg-1 .

Selective and sensitive determination of copper ions in soft drink based on high catalysis of hemin–graphene hybrid nanosheets coupled with enzyme inhibitions

A simple and selective colorimetric biosensor was presented based on high catalysis of hemin–graphene hybrid nanosheets coupled with enzyme inhibitions. Alcohol oxidase (AO) can catalyze the oxidations of methanol to produce hydrogen peroxide (H2O2). Subsequently, the resulting H2O2 could be catalyzed to oxidize 3,3,5,5-tetramethylbenzidine (TMB) and then produce a blue color reactions by using hemin–graphene hybrid nanosheets with intrinsic peroxidase-like activity. The activity of AO could be selectively inhibited by the copper ions, and therefore, the oxidase-catalyzed reactions of TMB was decreased. Fortunately, other metal ions even at 10 or 100 times copper ions concentrations showed no intensive inhibitions to the AO activity. Based on this functional materials-enzyme inhibitions system, a simple, selective and sensitive colorimetric biosensor was established to determine copper ions in soft drinks. The linear relationship was obtained from 5 nM to 1 μM, and the detections limit was 1.4 nM. The results were in good agreement with those obtained by the classic ICP-MS. It was demonstrated that the proposed method had an excellent practical perspective on the determinations of copper ions in foodstuff samples.

A Facile Approach to Covalently Functionalized Graphene Nanosheet Hybrids and Polymer Nanocomposites

AbstractHomogeneous dispersion and a good interface between polymer and filler is crucial to obtain high‐performance polymer composites. In this work, we use a novel method employing organic aminopropyl‐functionalized nanosilica sols (OAS‐sols) to functionalize graphene oxide (GO) and thereby synthesize OAS covalently grafted graphene hybrid nanosheets (OAS‐graphene). The spherical OAS covalently attached on the two‐dimensional (2D) nanosheet GO surfaces creates OAS‐graphene hybrids, which have large surface areas and homogeneous amino active sites distributed on the nanosheets. The OAS‐graphene gave an improved dispersion and interface compatibility as well as a decreased thermal interfacial resistance. As a result, the thermal conductivity and mechanical properties of the epoxy nanocomposites were significantly improved at low loading while maintaining high electrical insulative properties.

Hierarchical Layered WS2 /Graphene-Modified CdS Nanorods for Efficient Photocatalytic Hydrogen Evolution.

Graphene-based ternary composite photocatalysts with genuine heterostructure constituents have attracted extensive attention in photocatalytic hydrogen evolution. Here we report a new graphene-based ternary composite consisting of CdS nanorods grown on hierarchical layered WS2 /graphene hybrid (WG) as a high-performance photocatalyst for hydrogen evolution under visible light irradiation. The optimal content of layered WG as a co-catalyst in the ternary CdS/WS2 /graphene composites was found to be 4.2 wt %, giving a visible light photocatalytic H2 -production rate of 1842 μmol h(-1) g(-1) with an apparent quantum efficiency of 21.2 % at 420 nm. This high photocatalytic H2 -production activity is due to the deposition of CdS nanorods on layered WS2 /graphene sheets, which can efficiently suppress charge recombination, improve interfacial charge transfer, and provide reduction active sites. The proposed mechanism for the enhanced photocatalytic activity of CdS nanorods modified with hierarchical layered WG was further confirmed by transient photocurrent response. This work shows that a noble-metal-free hierarchical layered WS2 /graphene nanosheets hybrid can be used as an effective co-catalyst for photocatalytic water splitting.

Active Fe2O3 nanoparticles encapsulated in porous g-C3N4/graphene sandwich-type nanosheets as a superior anode for high-performance lithium-ion batteries

A novel composite anode of active Fe2O3 nanoparticles encapsulated in g-C3N4/graphene hybrid nanosheets has been developed for high-performance lithium-ion batteries.

Enhancing the cycling stability of Na-ion batteries by bonding SnS2ultrafine nanocrystals on amino-functionalized graphene hybrid nanosheets

An integrated composite tin sulfide bonded on an amino-functionalized graphene as a novel anode material for NIBs is reported. Tight contact with SnS2nanocrystals and discharge products on the amino-functionalized graphene interface results in excellent electrochemical performance.