Excellent Properties Of Graphene Research Articles

Studying the Adsorption Process of Cadmium Ions by Fe3O4/Lmethionine/ graphene Oxide and Graphene Aerogel Nanocomposites from Aqueous Environments

Background: In recent years, graphene oxide (GO) and its nanocomposites have shown effective performance in wastewater treatment. Moreover, graphene aerogels (GAs) have excellent properties, such as high surface area, high porosity, low density, high electrical conductivity, and good mechanical properties, due to the combination of three-dimensional porous structures and excellent properties of graphene. Methods: In this study, synthesis of Fe3O4/L-methionine and graphene oxide and graphene aerogel nanocomposites (Fe3O4/L-Met, Fe3O4/L-Met/GO, Fe3O4/L-Met/GA) was performed. Then, the synthesized nanocomposites were confirmed by FT-IR, SEM and BET analyses. The adsorption capacity of cadmium ion by methionine nanocomposites and the effect of various experimental parameters, such as contact time, initial metal ion concentration, and initial pH, on the adsorption process were investigated. Results: The results showed that Fe3O4/L-Met at pH 7 was suitable for Cd (II) removal with 90% removal efficiency. In addition, adsorption capacity experiments at a constant concentration of 50 ppm Cd2+ showed that more than 50% of Cd2+ ions could be adsorbed by Fe3O4/L-Met and reach equilibrium within 2 hours. Conclusion: Thus, Fe3O4/L-Met/GA showed high adsorption capacity towards Cd2+ (212.31 mg/g), which was significantly higher than Fe3O4/L-Met (201.23 mg/g). Finally, adsorption kinetics and isotherm studies were investigated. Adsorption data showed excellent fit with quasi-second order models (R2> 0.99) and Freundlich isotherm models.

A Geant4 Simulation on the Application of Multi-layer Graphene as a Detector Material in High-energy Physics

The excellent properties of graphene, such as its high thermal conductivity, high electrical conductivity, and high electron density, make it an ideal candidate as a detector material in high-energy physics applications. In this work, we demonstrate the feasibility of multi-layer graphene (MLG) as a detector material in a high-energy environment. The Geant4 software package was used to estimate the energy of the deposited electrons within various thicknesses of MLG, ranging from 3 to 20 nm. The efficiency of the MLG as a detector material was further analyzed from the scattering angle and the yield of the secondary particles produced from the electron interaction with the material. The incident electron’s kinetic energy used herein ranged between 30 keV and 1 GeV, at a particle fluence of 1×107 e/cm2. The results show that the deposited energy was relatively low for the interaction with 1 MeV electrons, and dramatically increased as the thickness increases beyond 15 nm. This result was further supported by the highest yield of gamma radiation recorded by the interaction with a kinetic energy larger than 1 MeV, for thickness larger than 15 nm. The results suggest that the MLG works best as a charged particle detector in low energy ranges, while for high energy ranges, a thickness over 15 nm is suggested. The findings demonstrate that a MLG with a thickness larger than 15 nm could potentially be used as a detector material in high-energy conditions.

Sagnac Ring Humidity Sensor With a Melting Cone Based on Graphene Properties

This study proposes a new type of fused cone Sagnac ring humidity sensor based on graphene properties. First, the single-mode optical fiber (SMF) is fused with the photonic crystal fiber (PCF) to form SMF-PCF-SMF interference. Then, the SMFs at both ends of the PCF are folded in half to form a ring. The ring is placed on the fiber pulling cone translation platform for pulling cone coupling. A Sagnac interferometer that connects the PCF is formed by applying the birefringence effect of melting cone coupling. The prepared interferometer is placed on a special optical platform, and graphene is coated on the fused cone area and the PCF. The excellent properties of graphene are utilized to measure humidity. Experimental results show that sensitivity to humidity is within the range of 36.0% relative humidity (RH)-75.3% RH, reaching 340.13pm/% RH. The sensor proposed in this study exhibits the characteristics of a simple structure, easy manufacturing, and low cost. It can be used as reference for the design and development of new sensors.

A Monolayer Composite of h-BN Doped by a Nano Graphene Domain: As Sensitive Material for SO2 Gas Detection

The development of two-dimensional materials with gas-sensitive properties has been a research focus in the field of materials science. Considering the excellent properties of graphene and hexagonal boron nitride, a monolayer composite is put forward and its potential for gas sensing has been investigated by density functional theory. Compared to common gases in the atmosphere and three other toxic gases, sulfur dioxide tends to have a strong mutual effect with this composite. Together with electronic analyses, it is proved that the composite presents excellent sensitivity toward sulfur dioxide molecules and the conductivity can be used as a vital parameter to diagnose the status of gas sensor. What’s more, a co-adsorption model demonstrates a favorable performance in high moisture working environment. Thus, we can reasonably draw the conclusion that the presented composite could be an eligible candidate for sulfur dioxide gas detection.

Rapid production of few layer graphene for energy storage via dry exfoliation of expansible graphite

Contrasted with the excellent properties of graphene, searching for an effective industrial production method is still necessary for progressing from the laboratory to commercial applications. This study presents a rapid and mass production method to get large-scale few layer graphene using the expansivity of expansible graphite. Under a suitable thermal treatment temperature (550 °C), the interlayer spacing of expansible graphite can increase sharply, then assisted with simple mechanical crushing, large-scale few layer graphene are obtained. By this dry exfoliation method, we exfoliated expansible graphite into graphene with high quality and structural integrity. The method can be achieved with yield of 93% and the Atomic force microscopy (AFM) results show the nanosheets have a thickness about 2.3 nm. Using the availability of this method, we show the excellent application values of graphene in phase change material (PCM) field for energy storage. This work shows huge potential applications of graphene in many practical fields.

Synthesis and characterization of graphene nanoribbons on hexagonal boron nitride

Graphene, as a typical representative of the two-dimensional material family, has received a wide attention due to its excellent physical and chemical properties. Graphene nanoribbon (GNR) is graphene in a width of several to a few tens of nanometers. GNRs not only inherit most of the excellent properties of graphene, but also have their own specific properties such as band gap opening and spin-polarized edge states, which make it the potential candidate in graphene based electronics in the future. Hexagonal boron nitride (h-BN), which has similar lattice constant with graphene, normally serves as an ideal substrate for graphene and GNRs. It can not only effectively preserve their intrinsic properties, but also benefit for the fabrication of electrical devices via popular semiconductor processes. In this paper, we reviewed the development history of research of graphene and GNRs on h-BN in recent years. The recent progress of physical properties is also discussed. In order to realize the large scale production of graphene and GNRs on h-BN, high quality h-BN multilayer is necessary. In addition, recent progresses about h-BN preparation methods are presented, and the progresses could pave the way for the further application of GNRs in the electronics. Finally, the research direction of graphene and GNRs on h-BN in the future is discussed.

Multistimuli-Responsive Intrinsic Self-Healing Epoxy Resin Constructed by Host–Guest Interactions

The self-healing abilities inside polymeric materials are desirable functions in materials science. Host–guest chemistry, combined with excellent properties of graphene, was used for the construction of multistimuli-responsive intrinsic self-healing epoxy materials. By ultraviolet (UV) curing, the unsaturated epoxy resin was connected with β-cyclodextrin/graphene complex through free radical copolymerization. The introduced complex, acting as macro-cross-linker and photothermal agent, can reconnect the damage-induced broken bonds through dynamic host–guest interaction. In this work, the epoxy composites exhibited a high healing efficiency of up to 79.2% and tensile strength of up to 20.8 MPa under heating or near-infrared stimulation, which represent relatively excellent values among all the reported intrinsic self-healing epoxy resin and host–guest self-healing systems.

Preparing graphene oxide–copper composite material from spent lithium ion batteries and catalytic performance analysis

The wide use of lithium ion batteries (LIBs) has created much waste, which has become a global issue. It is vital to recycle waste LIBs considering their environmental risks and resource characteristics. Anode graphite from spent LIBs still possess a complete layer structure and contain some oxygen-containing groups between layers, which can be reused to prepare high value-added products. Given the intrinsic defect structure of anode graphite, copper foils in LIB anode electrodes, and excellent properties of graphene, graphene oxide–copper composite material was prepared in this work. Anode graphite was firstly purified to remove organic impurities by calcination and remove lithium. Purified graphite was used to prepare graphene oxide–copper composite material after oxidation to graphite oxide, ultrasonic exfoliation to graphene oxide (GO), and Cu2+ adsorption. Compared with natural graphite, preparing graphite oxide using anode graphite consumed 40% less concentrated H2SO4 and 28.6% less KMnO4. Cu2+ was well adsorbed by 1.0 mg L−1 stable GO suspension at pH 5.3 for 120 min. Graphene oxide–copper composite material could be successfully obtained after 6 h absorption, 3 h bonding between GO and Cu2+ with 3/100 of GO/CuSO4 mass ratio. Compared to CuO, graphene oxide–copper composite material had better catalytic photodegradation performance on methylene blue, and the electric field further improved the photodegradation efficiency of the composite material.

Improvement in electrochemical performance of calcined LiNi0.5Mn1.5O4/GO

This study aimed to use the excellent properties of graphene as coating for the cathode material LiNi0.5Mn1.5O4. In this work, we added a calcination process based on the graphene oxide coating process from previous studies to obtain the calcined LiNi0.5Mn1.5O4/GO composite. The morphology and structure of the prepared samples were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Their performance as electrodes of lithium-ion battery was investigated by charge/discharge and cycle performance tests. The calcined LiNi0.5Mn1.5O4/GO composite obtained by the improved method presented a thin, compact, and uniform coating layer and improved the electrochemical performances of LiNi0.5Mn1.5O4 with no effect on the crystal structure. The calcined LiNi0.5Mn1.5O4/GO could deliver a capacity of 131.2mAhg−1, which was approximately 10mAhg−1 larger than that of LiNi0.5Mn1.5O4. After 280 cycles at 1C rate, the calcined LiNi0.5Mn1.5O4/GO could still deliver a reversible capacity of 123.2mAhg−1, retaining 94% of its initial reversible capacity.

Preparation of Graphene Quantum Dots and Their Biological Applications

As the derivatives of graphene, graphene quantum dots (GQDs) have the excellent properties of graphene, and photoluminescence (PL) properties that ordinary graphene does not possess, which is attributed to quantum confinement effect and boundary effect. Moreover, GQDs perform well in terms of cytotoxicity and biocompatibil- ity. Recently, the synthetic method of GQDs is increasingly diverse, which is usually divided into two main groups: top-down and bottom-up. With increasing application of GQDs in biomedical field, higher requirements on their morphology and size control are put forward. In this paper, we focus on the synthetic methods that are promising to control morphology and size of GQDs. Advantages and disadvantages of these methods are listed and analyzed comparatively. The biological applications of GQDs, including biological imaging, biological sensors, drug delivery and antibacterial agents, etc. are introduced. Suggestions on the choice of synthetic method for preparation of GQDs are given based on the requirements of diverse applications. The remained problems and the development directions in the research of GQDs are put forward.

Rapid synthesis of graphene/cobalt hydroxide composite with enhanced electrochemical performance for supercapacitors

A simple and rapid one-pot process is developed for the synthesis of reduced graphene oxide/cobalt hydroxide (rGO/Co(OH)2) composite. The morphology and microstructure of the composite are examined by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Both morphology and element analyses confirm that Co(OH)2 nanoparticles are homogeneously and tightly attached on the surfaces of rGO. The electrochemical performances of the rGO/Co(OH)2 composite as electrode materials for supercapacitors are systematically investigated. A synergistic effort built from the excellent properties of graphene and fine structure of the composite guarantees its superior capacitive performances than those of pure rGO and Co(OH)2. The specific capacitance of the rGO/Co(OH)2 composite reaches 474 F g−1 at a current density of 1 A g−1 and this value can even retain 300 F g−1 at a high current density of 10 A g−1, showing a relatively good rate capability. Moreover, the specific capacitance of this electrode still remains 90% after 1000 times of cycling, demonstrating a good cycle stability of this composite.

Effectively improved field emission for graphene film by mechanical surface modification

A mechanical surface treatment is presented by using adhesive tape to modify the surface morphology of graphene cathodes and to improve their field emission properties. The treated graphene cathodes have numerous vertical sharp edges, which act as excellent field emission sites. Effectively improved field emission properties with low turn on field, low threshold field, high emission current density and high field enhancement factor are obtained due to the full utilization of the unique structure and excellent properties of graphene.

Electrochemical sensors based on graphene materials

Single–layered graphene, emerging as a true two–dimensional nanomaterial, has tremendous potential for electrochemical catalysis and biosensing as a novel electrode material. Considering the excellent properties of graphene, such as large surface–to–volume ratio, high conductivity and electron mobility at room temperature, low energy dynamics of electrons with atomic thickness, robust mechanical and flexibility, we give a general view of recent advances in electrochemical sensors based on graphene. We are highlighting here important applications of graphene and graphene nanocomposites, and the assay strategies in electrochemical sensors for DNA, proteins, neurotransmitters, phytohormones, pollutants, metal ions, gases, hydrogen peroxide, and in medical, enzymatic and immunosensors.