Graphene Materials Research Articles

Two-Dimensional Pentagonal Materials with Parabolic Dispersion and High Carrier Mobility

Materials with high carrier mobility, represented by graphene, have garnered significant interest. However, the zero band gap arising from linear dispersion cannot achieve an ideal on–off ratio in field-effect transistors (FETs), limiting practical applications in certain fields. In contrast, parabolic dispersion usually exhibits extremely high carrier mobility and an appropriate band gap. In this work, we predicted a planar pentagonal lattice composed entirely of pentagons (namely penta-MX2 monolayer), where M = Ni, Pd and Pt, X = group V elements. Using first-principles calculations, we demonstrated a parabolic dispersion within this framework, which results in intriguing phenomena, such as a direct band gap (0.551–1.105 eV) and extraordinary high carrier mobility. For penta-MX2 monolayer, the carrier mobility can attain ~1 × 108 cm2 V−1 s−1 (PBE), surpassing those of black phosphorene, graphene and 2D hexagonal materials. This monolayer also displays anisotropic mechanical properties and significant absorption peaks in the ultraviolet spectrum. Remarkably, 2D penta-MX2 monolayers are promising for successful experimental exfoliation, particularly when X is a nitrogen element, opening up new possibilities for designing two-dimensional semiconductor materials characterized by high carrier mobility.

Effects of Graphene Materials on Asphalt and Asphalt Mixture

Effects of Graphene Materials on Asphalt and Asphalt Mixture

CRISPR–Cas Systems Associated with Electrolyte-Gated Graphene-Based Transistors: How They Work and How to Combine Them

In this review, recent advances in the combination of CRISPR–Cas systems with graphene-based electrolyte-gated transistors are discussed in detail. In the first part, the functioning of CRISPR–Cas systems is briefly explained, as well as the most common ways to convert their molecular activity into measurable signals. Other than optical means, conventional electrochemical transducers are also developed. However, it seems that the incorporation of CRISPR/Cas systems into transistor devices could be extremely powerful, as the former provides molecular amplification, while the latter provides electrical amplification; combined, the two could help to advance in terms of sensitivity and compete with conventional PCR assays. Today, organic transistors suffer from poor stability in biological media, whereas graphene materials perform better by being extremely sensitive to their chemical environment and being stable. The need for fast and inexpensive sensors to detect viral RNA arose on the occasion of the COVID-19 crisis, but many other RNA viruses are of interest, such as dengue, hepatitis C, hepatitis E, West Nile fever, Ebola, and polio, for which detection means are needed.

2D Nitrogen-Doped Graphene Materials for Noble Gas Separation.

Noble gases, notably xenon, play a pivotal role in diverse high-tech applications. However, manufacturing xenon is an inherently challenging task, due to its unique properties and trace abundance in the Earth's atmosphere. Consequently, there is a pressing need for the development of efficient methods for the separation of noble gases. Using mild fluorographene chemistry, nitrogen-doped graphene (GNs) materials are synthesized with abundant aromatic regions and extensive nitrogen doping within the vacancies and holes of the aromatic lattice. Due to the organized interlayer "nanochannels", nitrogen functional groups, and defects within the two-dimensional (2D)structures, GNs exhibits effective selectivity for Xe over Kr at low pressure. This enhanced selectivity is attributed to the stronger binding affinity of Xe to GN compared to Kr. The adsorption is governed by London dispersion forces, as revealed by theoretical calculations using symmetry-adapted perturbation theory (SAPT). Investigation of other GNs differing in nitrogen content, surface area, and pore sizes underscores the significance of nitrogen functional groups, defects, and interlayer nanochannels over thesurface area in achieving superior selectivity. This work offers a new perspective on the design and fabrication of functionalized graphene derivatives, exhibiting superior noble gas storage and separation activity exploitable in gas production technologies.

Advances in Graphene Field Effect Transistors (FETs) for Amine Neurotransmitter Sensing

Amine neurotransmitters (NTs) are crucial in the central nervous system, and dysregulation in their levels is implicated in a spectrum of neurological disorders. Thus, a precise and timely assessment of their concentrations is critical for early diagnosis and treatment efficacy monitoring. Graphene-based field effect transistors (GFETs) have become a ground-breaking instrument in the detection of these NTs because of their exceptional electrical characteristics and adaptability. This paper summarises the significant advancements in GFET biosensors in amine NT detection and highlights developments in the selectivity, sensitivity, and limit of detection (LOD) attained by selecting various graphene materials and functionalisation approaches.

Computational Design of the Electronic Response for Volatile Organic Compounds Interacting with Doped Graphene Substrates

Changes in the work function provide a fingerprint to characterize analyte binding in charge transfer-based sensor devices. Hence, a rational sensor design requires a fundamental understanding of the microscopic factors controlling the modification of the work function. In the current investigation, we address the mechanisms behind the work function change (WFC) for the adsorption of four common volatile organic compounds (toluene, ethanol, 2-Furfurylthiol, and guaiacol) on different nitrogen-doped graphene-based 2D materials using density functional theory. We show that competition between the surface dipole moment change induced by spatial charge redistribution, the one induced by the pure adsorbate, and the one caused by the surface deformation can quantitatively predict the work function change. Furthermore, we also show this competition can explain the non-growing work function change behavior in the increasing concentrations of nitrogen-doped graphenes. Finally, we propose possible design principles for WFC of VOCs interacting with N-doped graphene materials.

Evaluation of the synergistic effect of platinum-supported graphene materials on methylcyclohexane decomposition via flow reactor experiments and reactive force-field molecular dynamics simulations

Hydrogen technology is a viable alternative to carbon-based energy sources. However, the widespread use of hydrogen energy is limited by its low volumetric energy density, complex supply chain, and difficulties related to hydrogen storage. This study investigates the influence of Pt-supported graphene additives on hydrogen formation and decomposition of methylcyclohexane (MCH), which is a potential hydrogen carrier, by conducting high-pressure liquid flow reactor experiments and reactive force-field molecular dynamics simulations. This investigation represents a notable improvement in the MCH decomposition and hydrogen generation efficiencies through enhanced catalytic dehydrogenation facilitated by Pt-decorated functionalized graphene sheets (Pt@FGSs). Experimental results indicate that under fixed reaction conditions, the bicomposite structure of the Pt@FGSs at a loading concentration of 50 ppmw reduces the dehydrogenation energy and increases the conversion rate by up to 45%. The yields of products such as hydrogen and low-carbon species are also significantly improved. Notably, hydrogen formation is enhanced by a factor of approximately 2, demonstrating the effectiveness of Pt@FGSs in facilitating fuel decomposition and promoting hydrogen production. In addition, reactive force-field molecular dynamics simulations elucidate possible enhancement mechanisms, in which Pt nanoparticles attach to FGSs and catalyze the dehydrogenation of MCH and its derivatives. The production of a higher amount of the produced hydrogen is evidenced by the desorption of H atoms attached to the Pt surface. This study provides valuable insights that can accelerate the transition towards sustainable and effective decarbonization strategies using MCH as a hydrogen carrier.

Catalytic chitosan/MXene/GO nanocomposite membrane for removing dye and heavy metals

This work reported the preparation of a catalytic nanocomposite nanofiltration (NF) membrane and its performance in removing dye and heavy metals without requiring UV irradiation. Two-dimensional (2D) materials MXene and graphene oxide (GO) were employed in developing chitosan-based catalytic nanocomposite membranes for the removal of dye molecules and heavy metals from textile industry wastewater. The incorporated MXene catalytically decomposed the hydrogen peroxide (H2O2) and generating reactive oxygen species (ROS), which oxidize methylene blue (MB) and reduce cobalt (Co2+) and copper (Cu2+) ions. The electron paramagnetic resonance spectroscopy and fluorescence emission spectroscopy confirmed the generation of superoxide radicals (•O2−). The fabricated chitosan/MXene/GO (CMG) membrane in this research exhibited high removal efficiencies of 96 %, 78 % and 76 % for dye, cobalt ions and copper ions, which were 4, 3.9 and 4 times higher than that of neat membrane, respectively. Similar results of 95 % were also observed in total organic matter (TOC) removal for both concentrations of dye. The CMG membrane also showed superior organic fouling resistance. The findings provided a new insight for non-UV dependent catalytic nanocomposite NF to efficiently remove hazardous contaminants such as dye and heavy metals from industrial effluent.

Non-Destructive Integration of Spark-Discharge Produced Gold Nanoparticles onto Laser-Scribed Graphene Electrodes for Advanced Electrochemical Sensing Applications

Gold nanoparticles (AuNPs) decorated graphene materials are preferable materials in a wide range of electrochemical applications, however, the current methods for preparing them have several limitations. Herein, we have developed a green, solution-free, and non-destructive method for the in-situ generation of AuNPs on laser-scribed graphene electrodes (LSGEs), addressing the limitations of traditional preparation methods. This novel technique, contrasting with the conventional solution-based electrochemical deposition, utilizes spark discharge to modify LSGEs, demonstrating superior performance in sensors and biosensors applications. Through comprehensive characterizations (scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectra, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Kelvin probe force microscopy (KPFM)), we observed significant distinctions in particle size, metal loading, stability, surface-to-volume ratio, and graphene quality between spark-discharge produced AuNPs (SP-AuNPs) and electrodeposition produced AuNPs (EC-AuNPs). The average particle sizes of the SP-AuNPs and EC-AuNPs are 10 nm and 38 nm, respectively. The SP-AuNPs modified LSGEs demonstrate exceptional electroanalytical performance in dopamine detection, with a broad detection range (0.6–90 µM) and low LOD (0.40 µM), further validated in human neuroblastoma cells SH-SY5Y. Our findings suggest that the spark discharge method represents a significant advancement in the synthesis of metal nanoparticle enhanced LSG electrodes, with broad implications for electrochemical sensing, biosensing, and biomedical applications.

Expression of Concern “ Structural modification of graphene material by silicon mono-doping and co-doping with heteroatoms as sensors for methyl tert-butyl ether (MTBE) as a fuel additive: Insight from DFT and MD simulation “ [Comput. Theoret. Chem. 1239 (2024) 114669]

Expression of Concern “ Structural modification of graphene material by silicon mono-doping and co-doping with heteroatoms as sensors for methyl tert-butyl ether (MTBE) as a fuel additive: Insight from DFT and MD simulation “ [Comput. Theoret. Chem. 1239 (2024) 114669]

High sensitivity and high figure of merit graphene mid-infrared multi-band tunable metamaterial perfect absorber

In the research of this paper, we have devised a mid-infrared band metamaterial perfect absorber made of graphene material. The absorber is composed of a traditional three-layer structure of MPA. The top layer is a graphene layer with a specific structure, with SiO2 as the dielectric layer and the gold film as the substrate. In the wavelength range of 5500 – 13000 nm, the graphene layer generates seven absorption peaks and shows ultra-high absorption efficiency. The respective absorption rates are 91.17%, 99.41%, 99.01%, 95.69%, 94.16%, 96.89%, and 95.01%. By verifying the absorption spectra and the principle of effective impedance matching, analyze the electric field distribution image of the xoy plane based on the principle of surface plasmon resonance, we have proved that it conforms to the classical physical theory and expounded the reason why the absorption peaks were formed. The comparison of different graphene patterns has confirmed the superiority of this structure. By changing the relaxation time and Fermi level of graphene, the tunability of the absorber structure has been verified. Changing the incident angle has proved its insensitivity to the polarization angle (0° - 50°). Finally, by calculating and comparing the figure of merit (FOM) and the sensitivity (S), it is shown that this structure has significant sensitivity and excellent application ability and value. We firmly believe that our absorber can be well applied in high-sensitivity sensors, filters and detectors, and can contribute to fields such as photoelectric detection, optical communication and photoelectric sensing.

Chitosan-grafted Graphene Materials for Drug Delivery in Wound Healing.

The effective and prompt treatment of wounds remains a significant challenge in clinical settings. Consequently, recent investigations have led to the development of a novel wound dressing production designed to expedite the process of wound healing with minimal adverse complications. Chitosan, identified as a natural biopolymer, emerges as an appealing option for fabricating environmentally friendly dressings due to its biologically degradable, nonpoisonous, and inherent antimicrobial properties. Concurrently, graphene oxide has garnered attention from researchers as an economical, biocompatible material with non-toxic attributes for applications in wound healing. Chitosan (CS) has been extensively studied in agglutination owing to its advantageous properties, such as Non-toxicity biological compatibility, degradability, and facilitation of collagen precipitation. Nonetheless, its limited Medium mechanical and antibacterial strength characteristics impede its widespread clinical application. In addressing these shortcomings, numerous researchers have embraced nanotechnology, specifically incorporating Metal nanoparticles (MNPs), to enhance the mechanical power and targeted germicide features of chitosan multistructures, yielding hopeful outcomes. Additionally, chitosan is a decreasing factor for MNPs, contributing to reduced cytotoxicity. Consequently, the combination of CS with MNPs manifests antibacterial function, superior mechanical power, and anti-inflammatory features, holding significant potential to expedite wound healing. This study delves into Based on chitosan graphene materials in the context of wound healing.

Casimir force tuning in 2D materials: effect of rotation in phosphorene

We theoretically examine the Casimir force with Lifshitz theory for two-dimensional media: graphene and phosphorene. We calculate the Casimir force for three different configurations: (a) phosphorene-graphene, (b) phosphorene-phosphorene (with rotation), and (c) a system composed of gold and a two-dimensional material (graphene or phosphorene). According to our calculations, we have determined that systems consisting solely of two-dimensional media can reduce the magnitude of the Casimir force by half or more, in comparison to systems composed of two-dimensional material and gold. The results show that in phosphorene configurations, high frequencies play a dominant role in contributing to the Casimir force, allowing greater force magnitudes for low interlayer distances compared to systems composed of gold or graphene. Our calculations also show that, as a result of the anisotropy of the phosphorene layers, it is possible to design a mechanical modulator with only two phosphorene layers by considering a relative rotation between them by an angle θ. In this regard, the anisotropy of phosphorene and the modulation of the separation between the phosphorene layers make it possible to tune the amplitude of Casimir force. The proposed configurations could lead to the development of nanotechnology applications incorporating 2D materials into their structures.

CVD graphene with high electrical conductivity: empowering applications

Abstract Graphene is an extraordinary material boasting a unique structure, enthralling properties, and promising application vistas. Particularly, the remarkable electrical conductivity of graphene confers it with an inimitable superiority in multiple fields. Endeavors have been continuously made to progressively elevate the conductivity of graphene materials that are synthesized using chemical vapor deposition (CVD), the primary means to prepare high-quality graphene in batches. From this perspective, we offer a comprehensive analysis and discussions on the growth, transfer, and post-treatment strategies evolved towards highly conductive graphene over the past five years. Large-area graphene films, ranging from monolayer to multilayer ones, are initially addressed, succeeded by graphene-based composites which enable traditional metals and non-metal materials to showcase novel or enhanced electrical performances. Eventually, an outlook for future directions to achieve higher electrical conductivity and to develop novel applications for CVD graphene materials is provided.

Applications of Graphene Materials in Optoelectronic Devices

Graphene is a groundbreaking material at the forefront of material science and nanotechnology area. Graphene exhibit special qualities, including great mechanical strength, strong electrical conductivity and thermal conductivity. Consequently, the optical property of graphene is focused in this work. The excellent optical properties of graphene make it a good candidate material for optoelectronic devices. In recent years, a great deal of research has been conducted on the use of graphene for optoelectronic devices. Therefore, conducting research in this field is of great significance. In this work, researches are analyzed and studied to gain new insights into this area. In addition, a summary of the prevalent synthesis methods utilized for the production of graphene is provided, accompanied by a detailed examination of the merits and demerits associated with each technique. Finally, the applications of graphene materials in optoelectronic devices are discussed in depth to further understand the development status of graphene materials. This work seeks to generate new ideas and directions for the future development of optoelectronic technology.

Graphene-Based Wound Dressings for Wound Healing: Mechanism, Technical Analysis, and Application Status.

The development of novel wound dressings is critical in medical care. Graphene and its derivatives possess excellent biomedical properties, making them highly suitable for various applications in medical dressings. This review provides a comprehensive technical analysis and the current application status of graphene-based medical dressings. Initially, we discuss the chemical structure and the fabrication method of graphene and its derivatives. We then provide a detailed summary of the mechanisms by which graphene materials promote wound repair across the four stages of wound healing. Subsequently, we categorize the types of graphene-based wound dressings and analyze corresponding characteristics. Finally, we analyze the challenges encountered at present and propose solutions regarding future development trends. This paper aims to serve as a reference for further research in skin tissue engineering and the development of innovative graphene-based medical dressings.

Sustainable Production of Biomass-Derived Graphite and Graphene Conductive Inks from Biochar.

Graphite is a commonly used raw material across many industries and the demand for high-quality graphite has been increasing in recent years, especially as a primary component for lithium-ion batteries. However, graphite production is currently limited by production shortages, uneven geographical distribution, and significant environmental impacts incurred from conventional processing. Here, an efficient method of synthesizing biomass-derived graphite from biochar is presented as a sustainable alternative to natural and synthetic graphite. The resulting bio-graphite equals or exceeds quantitative quality metrics of spheroidized natural graphite, achieving a Raman ID/IG ratio of 0.051 and crystallite size parallel to the graphene layers (La) of 2.08 µm. This bio-graphite is directly applied as a raw input to liquid-phase exfoliation of graphene for the scalable production of conductive inks. The spin-coated films from the bio-graphene ink exhibit the highest conductivity among all biomass-derived graphene or carbon materials, reaching 3.58 ± 0.16 × 104 Sm-1. Life cycle assessment demonstrates that this bio-graphite requires less fossil fuel and produces reduced greenhouse gas emissions compared to incumbent methods for natural, synthesized, and other bio-derived graphitic materials. This work thus offers a sustainable, locally adaptable solution for producing state-of-the-art graphite that is suitable for bio-graphene and other high-value products.

Graphene Synthesis by Electrochemical Reduction of Graphene Oxide and Its Characterizations

Graphene is one of the nanoscale materials that has attracted many researchers to continue in-depth study on its unique properties where both the graphene oxide (GO) and electrochemical reduced graphene oxide (ERGO) are the derivatives of graphene. GO and ERGO can be further modified chemically for many types of application such as sensor and water filter membrane. However, to restore the electrical property of graphene, GO should be reduced to ERGO. There are several types of reduction methods which are fast to produce good quality and high yield of graphene material. However, those methods use toxic chemicals to reduce GO which can bring negative impact to both human and environment. Therefore, an electrochemical approach can be carried out to solve this issue. This study presents the electrochemical synthesis of GO and electrochemical reduction of ERGO. All characterizations were conducted by using Fourier transform infrared (FTIR) spectroscopy, X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM).

Significant temperature tunability of the band gap in two-dimensional materials

Two-dimensional (2D) materials have great attentions due to their novel physical and chemical properties. The band gap Eg plays a significant role in influencing their applications, which can be changed by the temperature. In this work, taking the Group-IV materials (graphene, silicene, germanene, and stanene) as the examples, we first study the temperature-dependent Eg by employing the state-of-the-art electron-phonon renormalization calculations. It shows that the primary Eg at K-point is almost unchanged while that at Γ-point decreases directly with temperature increase in all the systems (e.g., Eg reduction in stanene from 100 K to 500 K is 0.006 eV at K-point and 0.148 eV at Γ-point, respectively). The differences are originated from the different chemical bond characteristics at band edges, which are π-bonding at K-point but (σ*) σ (anti-) bonding at Γ-point. The latter are more sensitive to the temperature-induced vibrations, such as the out-of-plane acoustic phonon modes in the three buckling systems. The strong sensitivity of σ-bonding to the vibrations can be further examplified by another four 2D systems (P4, InSb, MgCl2, and C2F2), screening from the database MatHub-2d. This phenomenon offers the temperature tunability for the band gaps at Γ-point of 2D materials, which may have more application significances in optoelectronics.

Recent Advancements of Graphene and Some Selected Graphene-Based Electrode Materials for Lithium-Ion Battery

Graphene is a two-dimensional monolayer of carbon atoms arranged in a hexagonal lattice consisting of sp2 hybridized conjugated carbon atoms and serves as a promising electrode material for lithium-ion batteries (LIBs) owing to its superior properties, including a high specific surface area (2630 m2g-1), a high theoretical capacity (744 mAhg-1), excellent electrical conductivity, and a wide electrochemical potential window. Despite having these superior properties, the restacking as well as the van der Waals forces of attraction among the graphene layers and the long path for Li-ion diffusion are factors that reduce the specific surface area and active site for Li-ion storage, which in turn influence the electrochemical performance of LIBs. The functionalization of graphene to porous graphene, graphene quantum dots, and graphene oxides, as well as the integration of graphene with other foreign materials such as transitional metal oxides, various heteroatoms (boron, nitrogen, sulfur, etc.), and covalent organic frameworks (COF), are the two main strategies that have been widely applied to improve the properties of graphene for Li-ion battery applications. In this review, recent works regarding the performance of graphene and graphenebased electrode materials for LIBs applications were reviewed and presented in detail. Moreover, various graphene fabrication techniques in terms of quality and quantity of graphene produced as well as the future overview of graphene and some selected graphene-based materials for LIBs applications have been assessed and summarized.