Applications Of Graphene Materials Research Articles

Applications of Graphene Materials in Lithium-ion Batteries

In recent years, the escalating global energy crisis and the ever-increasing concern over environmental pollution have stimulated extensive research efforts towards exploring new green energy sources and accelerating the transformation and upgrading of traditional energy structures. Lithium-ion batteries (LIBs), known for their exceptional properties including high energy density, excellent discharge performance, long lifespan, non-toxicity, and environmental friendliness, have been regarded as the backbone of new energy systems. Additionally, graphene, a two-dimensional novel nanomaterial, has recently gained attention as a kind of electrode material exhibiting great promise for utilization in LIBs due to exceptional performance attributes. Notably, significant evidence from current studies has revealed that the integration of graphene into LIBs leads to a substantial improvement in their electrochemical performance. However, advancements in the performance during cycling and the capacity for charging of LIBs remain imperative. Therefore, the investigation of materials based on graphene for enhancing the performance of LIBs holds substantial importance. This paper has various aspects related to the utilization of graphene and graphene-based composites materials in electrodes in LIBs. A comprehensive analysis is conducted on the current literature and recent progress in the respective field, including the modification of composites formed by integrating metal oxides with graphene, the usage of graphene as a conductive agent, etc. Furthermore, this paper provides an outlook on the future enhancements and developments concerning the utilization of graphene in LIBs. The findings and analyses presented in this study hope to contribute novel insights for researchers and encourage the development of LIBs with larger capacity and longerlasting operational capabilities.

A density functional study of the coronene-pyrrole system in relation to its possible application as NO2 and NH3 sensors

According to recent research on the application of graphene materials as sensors and particularly polypyrrole-graphene materials, which are especially promising, the functionalization of graphene with a pyrrole molecule might be considered a viable alternative as a NO2 and NH3 sensor. In this way, a graphene sheet simulated as a coronene molecule was used in order to test whether this kind of functionalization could be useful for detecting the NO2 and NH3 toxic gases with a relatively high sensitivity. NO2 was studied as an example of an electron acceptor molecule, and NH3 as an electron donor molecule. Both molecules were adsorbed on two different regions of the functionalized adsorbent, and the energy ranges found for adsorption were reported and compared with those of the pristine graphene. The results indicated that in the coronene-pyrrole system, pyrrole tends to lie almost parallel to the coronene sheet in a π-π stacking interaction between the two conjugated systems, being the closest distances of 3.0 and 3.2 Å. The use of Δ (ΔHOMO-LUMO) as a descriptor confirmed that the coronene-pyrrole system is a good option as a NO2- and NH3-sensor; therefore, it might be an easy and suitable descriptor for characterizing the performance of a sensor; all calculations were made using a Density Functional formalism, through a functional M06-2X in combination with the 6-31G(d,p) basis set.

Applications of Graphene-Based Materials in Sensors: A Review.

With the research and the development of graphene-based materials, new sensors based on graphene compound materials are of great significance to scientific research and the consumer market. However, in the past ten years, due to the requirements of sensor accuracy, reliability, and durability, the development of new graphene sensors still faces many challenges in the future. Due to the special structure of graphene, the obtained characteristics can meet the requirements of high-performance sensors. Therefore, graphene materials have been applied in many innovative sensor materials in recent years. This paper introduces the important role and specific examples of sensors based on graphene and its base materials in biomedicine, photoelectrochemistry, flexible pressure, and other fields in recent years, and it puts forward the difficulties encountered in the application of graphene materials in sensors. Finally, the development direction of graphene sensors has been prospected. For the past two years of the COVID-19 epidemic, the detection of the virus sensor has been investigated. These new graphene sensors can complete signal detection based on accuracy and reliability, which provides a reference for researchers to select and manufacture sensor materials.

Revealing intrinsic spin coupling in transition metal-doped graphene.

Graphene materials offer attractive possibilities in spintronics due to their unique atomic and electronic structures, which is in contrast to their limited applications in the design of sophisticated spintronic devices. This should be attributed to the lack of knowledge about the intrinsic characteristics of graphene materials, especially the diverse correlations between sites within the materials and their roles in spin-signal generation and propagation. This work comprehensively studies the spin couplings between transition metal atoms doped on graphene and reveals their potential application in spintronic device design through the realization of various logic gates. In addition, the effects of the distance between doped metal atoms and the number of carbon layers on the logic gate implementation further verify that the spin-coupling effect can exhibit a certain distance dependence and space propagation. The achievements in this work uncover the potential value of graphene materials and are expected to open up new avenues for exploring their application in the design of sophisticated spintronic devices.

A Review on Graphene Oxide Two-dimensional Macromolecules: from Single Molecules to Macro-assembly

Graphene oxide (GO), which consists of two-dimensional (2D) sp2 carbon hexagonal networks and oxygen-contained functional groups, has laid the foundation of mass production and applications of graphene materials. Made by chemical oxidation of graphite, GO is highly dispersible or even solubilized in water and polar organic solvents, which resolves the hard problem of graphene processing and opens a door to wet-processing of graphene. Despite its defects, GO is easy to functionalize, dope, punch holes, cut into pieces, conduct chemical reduction, form lyotropic liquid crystal, and assemble into macroscopic materials with tunable structures and properties as a living building block. GO sheet has been viewed as a single molecule, a particle, as well as a soft polymer material. An overview on GO as a 2D macromolecule is essential for studying its intrinsic properties and guiding the development of relevant subjects. This review mainly focuses on recent advances of GO sheets, from single macromolecular behavior to macro-assembled graphene material properties. The first part of this review offers a brief introduction to the synthesis of GO molecules. Then the chemical structure and physical properties of GO are presented, as well as its polarity in solvent and rheology behavior. Several key parameters governing the ultimate stability of GO colloidal behavior, including size, pH and the presence of cation in aqueous dispersions, are highlighted. Furthermore, the discovery of GO liquid crystal and functionalization of GO molecules have built solid new foundations of preparing highly ordered, architecture-tunable, macro-assembled graphene materials, including 1D graphene fibers, 2D graphene films, and 3D graphene architectures. The GO-based composites are also viewed and the interactions between these target materials and GO are carefully discussed. Finally, an outlook is provided in this field, where GO is regarded as macromolecules, pointing out the challenges and opportunities that exist in the field. We hope that this review will be beneficial to the understanding of GO in terms of chemical structure, molecular properties, macro-assembly and potential applications, and encourage further development to extend its investigations from basic research to practical applications.

Research advances in physiological toxicity of graphene on plants

Graphene is one of the most popular carbon nanomaterials that widely used in many fields due to its unique physical and chemical properties. The expanding production and application of graphene materials has led to their inputs into the environment, with increasing risks of environment and human health. Therefore, elucidating the potential toxic effects of graphene and the related mechanism are of significance to evaluate its ecological risk and bio-safety. To date, many studies have reported the physiotoxicological effects of graphene on plants. Literature showed that graphene had concentration-dependent effects on the physiological response of plants, including seed germination, growth, oxidative stress, photosynthetic characteristics, plant hormones, and metabolic processes. In the future, it is necessary to establish a widely accepted phytotoxicity evaluation system for the safe manufacture and use of graphene.

Application of graphene materials in tribology — analysis of state of the problem and the preliminary research

Present publication describes one of the most interesting materials discovered in recent years, which is graphene. This paperwork contains information about graphene’s structure, properties, applications and methods of synthesis. The special attention has been given to tribological applications of graphene structures, including the usage of the graphene itself in the composite materials, protective integuments, and additives to lubricants (oils, greases). This publication was based on the information and research results published in the international articles and preliminary researches realized at the Military University of Technology as well. The research results concern the changes of basic lubricants’ parameters, which contain different amount of graphene oxide (or comparatively of hexagonal boron nitride). The results obtained during the tests indicate that graphene oxide could improve lubricating abilities of oils and greases. Keywords: tribology, lubricants, graphene, graphene oxide.

Plasma jet printing for preparation of N-doped graphene electrode

Graphene, the 2-D allotrope of carbon, is well known for its remarkable electronic and optical properties. Nitrogen doping can manipulate local electronic structure and thus improve the performance of a graphene powered device. Therefore, developing a method of graphene production that is low in cost, simple in operation and high in controllability is important. It carries a vital value for the industrial applications of graphene materials in the future. For this study, graphene oxide (GO) and GO/AuNPs (gold nanoparticles) films were prepared using plasma jet printing technology. Then, a dielectric barrier discharge at a sub-atmospheric pressure in nitrogen gas was used to obtain N-doped and reduced graphene oxide (N-rGO). The microstructure of the sample was observed using a scanning electron microscope. Then, the materials were analyzed using X-ray diffraction, Raman spectra, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Finally, the cyclic voltammetry profiles and galvanostatic charge/discharge curves of N-rGO and N-rGO/AuNPs capacitors were tested. Results have indicated that the ultimate materials with a porous structure after the nitrogen plasma treatment presented a pretty good capacitor performance.

Graphene oxide and reduced graphene oxide induced neural pheochromocytoma-derived PC12 cell lines apoptosis and cell cycle alterations via the ERK signaling pathways.

Given the novel applications of graphene materials in biomedical and electronics industry, the health hazards of these particles have attracted extensive worldwide attention. Although many studies have been performed on graphene material-induced toxic effects, toxicological data for the effect of graphene materials on the nervous system are lacking. In this study, we focused on the biological effects of graphene oxide (GO) and reduced graphene oxide (rGO) materials on PC12 cells, a type of traditional neural cell line. We found that GO and rGO exerted significant toxic effects on PC12 cells in a dose- and time-dependent manner. Moreover, apoptosis appeared to be a response to toxicity. A potent increase in the number of PC12 cells at G0/G1 phase after GO and rGO exposure was detected by cell cycle analysis. We found that phosphorylation levels of ERK signaling molecules, which are related to cell cycle regulation and apoptosis, were significantly altered after GO and rGO exposure. In conclusion, our results show that GO has more potent toxic effects than rGO and that apoptosis and cell cycle arrest are the main toxicity responses to GO and rGO treatments, which are likely due to ERK pathway regulation.

Nanotoxicity of Graphene and Graphene Oxide

Graphene and its derivatives are promising candidates for important biomedical applications because of their versatility. The prospective use of graphene-based materials in a biological context requires a detailed comprehension of the toxicity of these materials. Moreover, due to the expanding applications of nanotechnology, human and environmental exposures to graphene-based nanomaterials are likely to increase in the future. Because of the potential risk factors associated with the manufacture and use of graphene-related materials, the number of nanotoxicological studies of these compounds has been increasing rapidly in the past decade. These studies have researched the effects of the nanostructural/biological interactions on different organizational levels of the living system, from biomolecules to animals. This review discusses recent results based on in vitro and in vivo cytotoxicity and genotoxicity studies of graphene-related materials and critically examines the methodologies employed to evaluate their toxicities. The environmental impact from the manipulation and application of graphene materials is also reported and discussed. Finally, this review presents mechanistic aspects of graphene toxicity in biological systems. More detailed studies aiming to investigate the toxicity of graphene-based materials and to properly associate the biological phenomenon with their chemical, structural, and morphological variations that result from several synthetic and processing possibilities are needed. Knowledge about graphene-based materials could ensure the safe application of this versatile material. Consequently, the focus of this review is to provide a source of inspiration for new nanotoxicological approaches for graphene-based materials.

Lithium Storage Characteristics and Possible Applications of Graphene Materials

Graphene materials are materials with a flat mono/few layer of carbon atoms tightly packed to a two-dimensional honeycomb lattice. Graphene materials are expected to be applied in lithium ion batteries due to their unique structural, mechanical and electrical properties. As an anode material, the charge/discharge characteristics of graphene materials is similar to those of low-temperature soft carbon materials, such as high capacity, low initial efficiency and large voltage hys- teresis. Although attractive results have been achieved for graphene as anode materials for LIBs, detailed lithium storage mechanisms are still not clear. The effects of the following several structural parameters including disorder degree, surface area, micropores, interlayer spacing, C/O ratio and layer number on the lithium storage properties are discussed. Thermally reduced graphene materials with a highly disordered structure and high surface area has exceptionally high reversible capac- ity. Micropores in graphene materials have a great impact on their electrochemical performance. Although these micropores can provide additional sites for increased reversible lithium storage, it can also results in severe capacity fading and voltage hysteresis. Oxygen functional groups and larger interlayer spacing may provide higher reversible capacity of graphene, but the micropores and defect-based reversible storage may be the main contribution. Effect of layer number on lithium storage mechanisms of graphene and the conclusion are still in debate. Graphene with rich oxygen functional groups is a promising cathode material with high capacity and rate performance for lithium storage. High specific capacity of graphene cathode is mainly ascribed to lithiation reaction of oxygen functional groups, such as epoxide and carbonyl groups. Lithiation of oxygen functional groups still requires further study for a full understanding. Based on the lithium storage characteristics of graphene anode and cathode, lithium ion capacitors with high energy density and graphene composite cathode materials for lithium ion batteries may be designed and developed in the future. Graphene based lithium ion capacitors facilitate the reversible lithium storage, which significantly improves the energy density of lithium ion capacitors compared to those of conventional systems based on activated carbon. LiFePO4 modified with graphene layers has reached 208 mAh/g in specific capacity. The excess capacity is attributed to the reversible reduction-oxidation reaction between the lithium ions of the electrolyte and the exfoli- ated graphene flakes.

Recent applications of graphene-based materials in capillary electrophoresis

Graphene and graphene-based materials have been widely applied in biochemical and chemical analysis because of its unique physical and chemical properties. Recent applications of graphene-based materials in capillary electrophoresis (CE) were highlighted, such as modification of amperometric detection electrode, preparation of monolithic column, modification of capillary inner wall and modification of microchip. The potential application of graphene materials in CE is discussed in this review.