Graphene-based Nanostructures Research Articles

Metal/Metal Oxide Modified Graphene Nanostructures for Electrical Biosensing Applications: A Review

Tremendous accomplishments have been made in the field of metal/metal oxide modified graphene nanostructures to overcome the problems of agglomeration and restacking in graphene biosensors. Some review articles are available on electrochemical biosensing applications of graphene based composites and hybrids. However, none of them have made significant contributions in their applications in the domain of field effect transistor (FET) and impedance biosensors. In this manuscript, the authors analytically summarize not only the state-of-the art electrochemical biosensors using metal/metal oxide modified graphene but also a detailed discussion on FET and impedance-based biosensors has been presented along with the comprehensive physics behind enhanced sensing performance of such devices. It has been observed that sub-femtomolar detection limits are achievable using FET and impedance based label free sensing which has been attributed to the metal nanoparticle induced modulation in band gap. Moreover, the technological advancements in the synthesis techniques based on encapsulation of various metal nanoforms onto electrochemically activated graphene to initiate more reactive sites on the graphene surface have been thoroughly compiled. Despite these advances, the use of graphene-based hybrid nanostructures for biosensors is still in its early stages and we have highlighted the existing challenges and indicated the future research direction.

Electric Directional Steering of Cathodoluminescence From Graphene-Based Hybrid Nanostructures

Controlling directional emission of nanophotonic radiation sources is fundamental to tailor radiation-matter interaction and to conceive highly efficient nanophotonic devices for on-chip wireless communication and information processing. Nanoantennas coupled to quantum emitters have proven to be very efficient radiation routers, while electrical control of unidirectional emission has been achieved through inelastic tunneling of electrons. Here we prove that the radiation emitted from the interaction of a high-energy electron beam with a graphene-nanoparticle composite has beaming directions which can be made to continuously span the full circle even through small variations of the graphene Fermi energy. Emission directionality stems from the interference between the double cone shaped electron transition radiation and the nanoparticle dipolar diffraction radiation. Tunability is enabled since the interference is ruled by the nanoparticle dipole moment whose amplitude and phase are driven by the hybrid plasmonic resonances of the composite and the absolute phase of the graphene plasmonic polariton launched by the electron, respectively. The flexibility of our method provides a way to exploit graphene plasmon physics to conceive improved nanosources with ultrafast reconfigurable radiation patterns.

Progress and Prospects on the Fabrication of Graphene-Based Nanostructures for Energy Storage, Energy Conversion and Biomedical Applications.

Graphene, a two-dimensional (2D) layered material has attracted much attention from the scientific community due to its exceptional electrical, thermal, mechanical, biological and optical properties. Hence, numerous applications utilizing graphene-based materials could be conceived in next-generation electronics, chemical and biological sensing, energy conversion and storage, and beyond. The interaction between graphene surfaces with other materials plays a vital role in influencing its properties than other bulk materials. In this review, we outline the recent progress in the production of graphene and related 2D materials, and their uses in energy conversion (solar cells, fuel cells), energy storage (batteries, supercapacitors) and biomedical applications.

Tunable lateral spin polarization and spin-dependent collimation in velocity-modulated ferromagnetic-gate graphene structures

The influence of spatial variation of Fermi velocity on the spin-polarized transport properties of massless Dirac fermions in proximity-induced ferromagnetic graphene junction was investigated. We found that the velocity ratio ξ causing the width of the spin conductance dip near the Dirac point is broadened as the Fermi velocity ratio increases. In contrast, the effect of the Fermi velocity mismatch does not affect the shifting of the Dirac point. It leads to the indirect measurement of the Fermi velocity ratio that can be tuned by the spin-dependent conductance. In addition to the presence of both the exchange field and the Fermi velocity modulation, we found high spin filtering occurs when the Fermi velocity ratio ξ ≥ 1. Due to the transmission probability of electron with spin down, T↓ is blocked by the effect of Fermi velocity modulation similar to waves travelling through a different media. Moreover, we also found that the resonant transmission of the electron with spin up can be perfectly transmitted through the Fermi velocity barrier at the limit injected angle θ → π/2 for H/EF ≈ 1. The spin transport properties can be controlled by suitably modifying the strength of the ferromagnetic insulator and varying the Fermi velocity modulation, which leads to the highest spin polarization. By manipulating the behavior of spin-dependent collimation and spin beam splitting in this structure, we proposed a spin transport device for making lateral spin polarization. These interesting features will help make the development of spintronic devices in the graphene-based nanostructure.

Analytical Solution for Static and Dynamic Analysis of Graphene-Based Hybrid Flexoelectric Nanostructures

Owing to their applications in devices such as in electromechanical sensors, actuators and nanogenerators, the consideration of size-dependent properties in the electromechanical response of composites is of great importance. In this study, a closed-form solution based on the linear piezoelectricity, Kirchhoff’s plate theory and Navier’s solution was developed, to envisage the electromechanical behaviors of hybrid graphene-reinforced piezoelectric composite (GRPC) plates, considering the flexoelectric effect. The governing equations and respective boundary conditions were obtained, using Hamilton’s variational principle for achieving static deflection and resonant frequency. Moreover, the different parameters considering aspect ratio, thickness of plate, different loadings (inline, point, uniformly distributed load (UDL), uniformly varying load (UVL)), the combination of different volume fraction of graphene and piezoelectric lead zirconate titanate are considered to attain the desired bending deflection and frequency response of GRPC. Different mode shapes and flexoelectric coefficients are also considered and the results reveal that the proper addition of graphene percentage and flexoelectric effect on the static and dynamic responses of GRPC plate is substantial. The obtained results expose that the flexoelectric effect on the piezoelastic response of the bending of nanocomposite plates are worth paying attention to, in order to develop a nanoelectromechanical system (NEMS). Our fundamental study sheds the possibility of evolving lightweight and high-performance NEMS applications over the existing piezoelectric materials.

Outstanding slow-light effect for graphene metasurface in terahertz

So as to realize good slow-light effects in a simple graphene-based nano-structure, a n-shaped graphene metasurface is proposed in this paper. Through the detailed studies, plasmon induced transparency (PIT) can be observed in the proposed metasurface, and the bright-dark mode is used to explain the physical mechanism of this phenomenon. Especially, a convenient modulation for PIT can be realized through Fermi level and carrier mobility. In addition, a developed coupled mode theory (CMT) is established for demonstrating the optical responses of the n-shaped graphene metasurface, and the theoretical results are in well agreement with the numerical results. At last, an excellent slow-light effect with ultra-high group index of 2510 can be achieved in the proposed simple graphene-based metasurface. The outstanding performance of slow-light effect may play important roles for designing the plasmonic slow-light devices in terahertz.

SARS‐CoV‐2 Inhibitors: Graphene Sheets with Defined Dual Functionalities for the Strong SARS‐CoV‐2 Interactions (Small 11/2021)

In article number 2007091, Ievgen S. Donskyi, Chuanxiong Nie, Kai Ludwig, Jakob Trimpert, and co-workers report an idea of designing a graphene-based nanostructure that can rupture corona virions. This study shows that a combination of two different mechanisms at nanobiointerfaces by manipulation of the functionality of nanoplatform is an efficient way to control and accelerate biointeractions and to produce new vectors for future antiviral applications.

Increasing the biocompatibility of graphene-based hybrid nanostructures with glycopolymer.

Hybrid nanostructures decorated with glycopolymers are appropriate for biomedical applications. In this paper, the results are obtained from nanographene (NG) decorated with glycoblock copolymer to increase their potential in use in therapies and in examining lectin interactions. A pyren-1-ylmethyl 4-cyano-4-((phenylcarbonothioyl)thio)pentanoate (CPADB-py) chain transfer agent was used in the synthesis of methyl methacrylate glycoblock copolymers (P2 and P3) by reversible addition-fragmentation chain transfer (RAFT) polymerization to adhere the polymer to the nanographene surface. Hybrid nanographenes (NG-1 and NG-2) were obtained by the non-covalent interaction of deprotected P2 and P3 with different fructopyranose groups (3-O-methacryloyl-1,2:4,5-di-O-isopropylidene-β-D-fructopyranose and 1-O-methacryloyl-2,3:4,5-di-O-isopropylidene-β-D-fructopyranose) in their backbones. Images obtained from transmission electron microscopy (TEM) of NG-1 and NG-2 show that glycoblock copolymer coating was performed homogeneously. Moreover, thermal gravimetric analysis (TGA) also confirmed a glycoblock copolymer coating of NG-1 and NG-2 by weight loss of 41% and 31%, respectively. In the last step of the study, the binding ability of glycoblock copolymers (P2-hyd and P3-hyd) with concanavalin A (ConA) lectin was investigated by a turbidimetric assay. Promising results were obtained from P3-hyd for the ConA interactions. Hence, this study may open a new avenue in the design of new multifunctional glyconanomaterials that show favorable binding properties with lectins.

Critical Influence of the Processing Route on the Mechanical Properties of Zirconia Composites with Graphene Nanoplatelets

Graphene-based nanostructures, used as potential reinforcement in ceramic composites, have a great tendency to agglomerate. This requires the use of homogenization techniques during the powder processing, posing the need to evaluate how these techniques affect the microstructure and the mechanical properties of the resulting composites. The influence of the processing route on the properties of 3YTZP (3 mol % yttria tetragonal zirconia polycrystals) ceramic composites with 10 vol % cost-effective GNP (graphene nanoplatelets) has been addressed. Four different powder processing routines combining ultrasonic powder agitation (UA) and planetary ball milling (PBM) in wet and dry media have been used and all the composites were densified by spark plasma sintering (SPS). The mechanical properties at room temperature in the macroscale have been assessed by Vickers indentations, four-point bending tests and the impulse-echo technique, while instrumented indentation was used to measure the hardness and Young’s modulus at the nanoscale. The application of dry-PBM enhances greatly the mechanical and electrical isotropy of the composites, slightly increases the hardness and lowers the elastic modulus, independently of the application of UA. The combination of UA and dry-PBM enhances the flexure strength by 50%, which is desirable for structural applications.

NANOPARTICLES OF NOBLE METALS ON THE SURFACE OF GRAPHENE FLAKES

Carbon is a spread element that has many different reaction combinations. Obtaining new composite materials based on nanoparticles is a very actual and perspective topic because nanoparticles possess unique properties. These properties are retained and even amplified when nanoparticles are located in various matrixes. Furthermore, nowadays, the creation of graphene-based composites and graphene-related structures is a promising area of synthesis of composite nanomaterials. Previous research has determined that graphene has a unique set of electrophysical, thermal, optical, and mechanical properties. In this study, the synthesis of nanocomposites representing nanoparticles of noble metals (Au, Pd, Rh) on the surface of graphene flakes were carried out, and the study of their composition, structure, physical and chemical properties, and possible applications in catalysis. The immobilization of nanoparticles on the surface of graphene oxide and graphene was developed, and the original method of synthesis of nanocomposite noble metal nanoparticles on the graphene flakes surface using supercritical isopropanol as a reduction agent for the transformation of graphene oxide into graphene was created. The study of physical and chemical properties of the obtained nanocomposites and results of the study of obtained nanocomposites as catalysts for model organic reactions of cross-coupling and hydroformylation showed that it is possible to create the graphene-based nanostructures as effective functional nanomaterials. Research on the synthesis of graphene compounds and its unique physical properties form a promising direction in the chemistry and physics of new inorganic functional materials. The resulting nanocomposites can be used in such branches as electrodes for LEDs and solar cells, field-effect transistors, supercapacitors, sensors, fuel cells.

Thermal conduction in three-dimensional printed porous samples by high resolution infrared thermography

The thermal conductivity (κ) is a key parameter that defines many of the technological uses of three-dimensional (3D) porous architectures. Despite the variety of methods for determining κ, problems generally arise when researchers try to apply them to cellular materials and 3D structures. The present work proposes an affordable lab-made device for analysing anisotropic heat flow in 3D porous architectures via high resolution infrared thermography. The method is validated using dense materials of known thermal conductivity. Temperature gradients measured for porous specimens have been correlated to the thermal conductivity estimated from a simple resistors model, assessing the main factors that affect the experimental measurements. The porous specimens of SiC, MAX-phase and graphene-based nanostructures are in-house manufactured by direct ink writing (robocasting).

Current Research of Graphene-Based Nanocomposites and Their Application for Supercapacitors.

This review acmes the latest developments of composites of metal oxides/sulfide comprising of graphene and its analogues as electrode materials in the construction of the next generation of supercapacitors (SCs). SCs have become an indispensable device of energy-storage modes. A prompt increase in the number of scientific accomplishments in this field, including publications, patents, and device fabrication, has evidenced the immense attention they have attracted from scientific communities. These efforts have resulted in rapid advancements in the field of SCs, focusing on the development of electrode materials with features of high performance, economic viability, and robustness. It has been demonstrated that carbon-based electrode materials mixed with metal oxides and sulfoxides can perform extremely well in terms of energy density, durability, and exceptional cyclic stability. Herein, the state-of-the-art technologies relevant to the fabrication, characterization, and property assessment of graphene-based SCs are discussed in detail, especially for the composite forms when mixing with metal sulfide, metal oxides, metal foams, and nanohybrids. Effective synthetic methodologies for the nanocomposite fabrications via intercalation, coating, wrapping, and covalent interactions will be reviewed. We will first introduce some fundamental aspects of SCs, and briefly highlight the impact of graphene-based nanostructures on the basic principle of SCs, and then the recent progress in graphene-based electrodes, electrolytes, and all-solid-state SCs will be covered. The important surface properties of the metal oxides/sulfides electrode materials (nickel oxide, nickel sulfide, molybdenum oxide, ruthenium oxides, stannous oxide, nickel-cobalt sulfide manganese oxides, multiferroic materials like BaMnF, core-shell materials, etc.) will be described in each section as per requirement. Finally, we will show that composites of graphene-based electrodes are promising for the construction of the next generation of high performance, robust SCs that hold the prospects for practical applications.

Graphene-family materials in electrochemical aptasensors.

The study of graphene-based carbon nanocomposites has remarkably increased in recent years. Functionalized graphene-based nanostructures, including graphene oxide and reduced graphene oxide, have great potential as new innovative electrode materials in the fabrication of novel electrochemical sensors. Electrochemical sensors based on aptamers attracted great attention because of their high sensitivity and selectivity, and simple instrumentation, as well as low production cost. Aptamers as a potent alternative to antibodies are functional nucleic acids with a high tendency to specific analytes. Electrochemical aptasensors show specific recognition ability for a wide range of analytes. Although aptamers are selected in vitro in contrast to antibodies, they are interesting due to advantages like high stability, easy chemical modifications, and the potential to be employed in nanostructured device fabrication or electrochemical sensing devices. Recently, new nanomaterials have shown a significant impact on the production of electrochemical sensors with high efficiency and performance. This review aims to give an outline of electrochemical aptasensors based on the graphene family materials and discuss the detection mechanism in this type of aptasensors. The present review summarizes some of the recent achievements in graphene-based aptasensors and includes their recent electroanalytical applications. Graphical Abstract Graphical Abstract.

Single-Walled Carbon Nanohorns as Promising Nanotube-Derived Delivery Systems to Treat Cancer.

Cancer has become one of the most prevalent diseases worldwide, with increasing incidence in recent years. Current pharmacological strategies are not tissue-specific therapies, which hampers their efficacy and results in toxicity in healthy organs. Carbon-based nanomaterials have emerged as promising nanoplatforms for the development of targeted delivery systems to treat diseased cells. Single-walled carbon nanohorns (SWCNH) are graphene-based horn-shaped nanostructure aggregates with a multitude of versatile features to be considered as suitable nanosystems for targeted drug delivery. They can be easily synthetized and functionalized to acquire the desired physicochemical characteristics, and no toxicological effects have been reported in vivo followed by their administration. This review focuses on the use of SWCNH as drug delivery systems for cancer therapy. Their main applications include their capacity to act as anticancer agents, their use as drug delivery systems for chemotherapeutics, photothermal and photodynamic therapy, gene therapy, and immunosensing. The structure, synthesis, and covalent and non-covalent functionalization of these nanoparticles is also discussed. Although SWCNH are in early preclinical research yet, these nanotube-derived nanostructures demonstrate an interesting versatility pointing them out as promising forthcoming drug delivery systems to target and treat cancer cells.

Graphene-Based Nanoparticles as Potential Treatment Options for Parkinson's Disease: A Molecular Dynamics Study.

IntroductionThe study of abnormal aggregation of proteins in different tissues of the body has recently earned great attention from researchers in various fields of science. Concerning neurological diseases, for instance, the accumulation of amyloid fibrils can contribute to Parkinson’s disease, a progressively severe neurodegenerative disorder. The most prominent features of this disease are the degeneration of neurons in the substantia nigra and accumulation of α-synuclein aggregates, especially in the brainstem, spinal cord, and cortical areas. Dopamine replacement therapies and other medications have reduced motor impairment and had positive consequences on patients’ quality of life. However, if these medications are stopped, symptoms of the disease will recur even more severely. Therefore, the improvement of therapies targeting more basic mechanisms like prevention of amyloid formation seems to be critical. It has been shown that the interactions between monolayers like graphene and amyloids could prevent their fibrillation.MethodsFor the first time, the impact of four types of last-generation graphene-based nanostructures on the prevention of α-synuclein amyloid fibrillation was investigated in this study by using molecular dynamics simulation tools.ResultsAlthough all monolayers were shown to prevent amyloid fibrillation, nitrogen-doped graphene (N-Graphene) caused the most instability in the secondary structure of α-synuclein amyloids. Moreover, among the four monolayers, N-Graphene was shown to present the highest absolute value of interaction energy, the lowest contact level of amyloid particles, the highest number of hydrogen bonds between water and amyloid molecules, the highest instability caused in α-synuclein particles, and the most significant decrease in the compactness of α-synuclein protein.DiscussionUltimately, it was concluded that N-Graphene could be the most effective monolayer to disrupt amyloid fibrillation, and consequently, prevent the progression of Parkinson’s disease.

One-pot hydrothermal preparation of B and N co-doped graphene aerogels loaded with cobalt oxides for the synergistic enhancement of oxygen reduction electrocatalysis

Developing non-precious metal catalysts with superior activity and stability for the oxygen reduction reaction (ORR) remains challenging for application of full cells. In this work, three-dimensional boron and nitrogen co-doped graphene aerogels loaded with cobalt oxides (3D BNGCo) catalysts were designed and prepared by a one-pot hydrothermal method. In this 3D nanoarchitecture, CoOx nanoparticles were evenly spread over the BNG surface without aggregation. As a non-precious metal cathode electrocatalyst, the 3D BNG-Co catalyst favors a direct 4e− pathway and exhibits excellent activity towards ORR, as well as superior long-term durability. In 0.1 M KOH solution, its onset potential, half-wave potential and limiting current density for the ORR reach −0.02 V (vs. Ag/AgCl), −0.3 V (vs. Ag/AgCl) and 5.6 mA cm−2, which are comparable to those of commercial 20 wt% Pt/C catalyst. The good electrochemical activities of the as-fabricated catalyst could be attributed to the 3D network foam, unique electronic structure, and the synergy effect of pyridinic N together with BC3 phases. The present work sheds insights into the effects of diatomic doping of the 3D graphene-based nanostructures in the field of ORR and and can be extended to other catalytic systems.

Current modulation in graphene p–n junctions with external fields

In this work we describe a proposal for a graphene-based nanostructure that modulates electric current even in the absence of a gap in the band structure. The device consists of a graphene p–n junction that acts as a Veselago lens that focuses ballistic electrons on the output lead. Applying external (electric and magnetic) fields changes the position of the output focus, reducing the transmission. Such device can be applied to low power field effect transistors, which can benefit from graphene’s high electronic mobility.

Thermally reduced graphene oxide as an electrode for CDI processes: A compromise between performance and scalability?

Capacitive deionization (CDI) is an alternative water desalination technology, which was investigated extensively in the last decade. The choice of electrodes' materials plays a major role in the electrosorption performance, affecting the whole desalination process. Graphene-based nanostructures in various types were extensively studied owing to their superior inherent physico-chemical properties. Whereas excellent electrosorption performance was reported – expressed in terms of salt adsorption capacity (SAC) or average salt adsorption rate (ASAR) – the cost-benefit of graphene-based electrodes, considering total production cost and much lower price of commercial activated carbon, is still controversial.Here, we explore partially exfoliated thermally reduced graphene oxide (GO) – denoted as PE-rGO – prepared by scalable low-temperature thermal exfoliation of GO under air atmosphere. PE-rGO displays a “paper-like” structure with nanoscale pores. By the construction of a lab-scale system, a few grams of product were produced in one batch. A PE-rGO electrode assembled in membrane-CDI three-electrode configuration showed moderate to high SAC of around 13 mg/g under potential window of 0–550 mV versus Ref. electrode in 2000 ppm NaCl solution. However, the energy consumption was shown to be nearly constant with increasing ASAR. This has significant implications for the energy consumption and the projected capital costs.

Two-step strategy for improving the tribological performance of Si3N4 ceramics: Controlled addition of SiC nanoparticles and graphene-based nanostructures

The tribological behaviour of silicon nitride (Si3N4) ceramics is investigated using a two-step strategy. A set of ceramic composites containing silicon carbide nanoparticles (SiCn) is developed and, subsequently, graphene-based fillers are added to the Si3N4/SiC composite with the best tribological performance. The friction coefficient and the wear rate of Si3N4 are reduced up to 22 % and 40 %, respectively, when a 10 vol.% of SiCn is incorporated into the ceramic matrix due to its improved mechanical response. Si3N4/SiC composites containing 11 vol.% of graphene nanoplatelets (GNPs) or reduced graphene oxide sheets (rGOs) are analysed under isooctane lubrication and dry testing. rGOs composite leads to an important decrease of the friction coefficient (50 %) under lubricated conditions, and an enhancement of the wear resistance (44 %) under dry sliding tests, as compared to the reference Si3N4/SiC. The best performance of rGOs composite is due to the nature of the lubricating tribofilm and its excellent toughness.

Effect of Solvents on Fe–Lignin Precursors for Production Graphene-Based Nanostructures

Kraft lignin was catalytically graphitized to graphene-based nanostructures at high temperature under non-oxidative atmospheres. To obtain the best catalytic performance, a uniform catalyst–lignin mixture must be made by bonding transitional metal (M) ions to oxygen (O), sulfur (S) or nitrogen (N)-containing functional groups in kraft lignin. One of the strategies is to dissolve or disperse kraft lignin in a suitable solvent, whereby the polymer chains in the condensed lignin molecules will be detangled and stretched out while the functional groups are solvated, and when mixing lignin solution with catalyst metal solution, the solvated metal ions in an aqueous solution can diffuse and migrate onto lignin chains to form M-O, M-S, or M-N bonds during the mixing process. Therefore, solvent effects are important in preparing M–lignin mixture for production of graphene-based nanostructures. Fe–lignin precursors were prepared by dissolving lignin with different solvents, including water, methanol, acetone, and tetrahydrofuran (THF). Solvent effects on the catalytic performance, size and morphology of graphene-based nanostructures were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), and nitrogen sorption measurements. The sizes, morphologies, and catalytic properties of the products obtained from Fe–lignin precursors are greatly influenced by the solvents used. It was found that Fe–lignin (THF) had the highest iron dispersion and the smallest iron particle size. Furthermore, Fe–lignin (THF) exhibited the best catalytic performance for graphitization of kraft lignin while the graphitization degree decreased in the order: Fe–lignin(THF) > Fe–lignin(Acetone) > Fe–lignin(methanol) > Fe–lignin(water).