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Dependence of energy on optimization step. The top panel is corresponding to the triangular graphone. The geometries and forces on each atom are shown for the corresponding step: (a) n = 1 (triangular graphone), (b) n = 175, (c) n = 240, (d) n = 278 and (e) n = 417 (rectangular graphone). The bottom panel is corresponding to the geometry shown in Fig. 1(b). The geometries and forces on each atom are shown for the corresponding step: (a) n = 1, (b) n = 90, (c) n = 160, and (d) n = 260 (rectangular graphone).
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Graphone is half-hydrogenated graphene. The structure of graphone is
illustrated as trigonal adsorption of hydrogen atoms at first. However, we
found the trigonal adsorption is metastable. We present an illustration in
detail to explain how a trigonal adsorption geometry evolves into a rectangular
adsorption geometry. We check the change of magneti...
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Citations
... Furthermore, graphene has an extremely high electric conductivity [2], and it is also one of the strongest known two-dimensional materials, which is, at the same time, quite flexible. Since the synthesis of graphene, many other two-dimensional materials have been discovered or proposed, including graphone [3], graphane [4], graphene oxide [5], phagraphene [6], graphyne [7], etc., which are of interest due to their unique atomic structure, as well as mechanical, optical, and electronic properties [8,9]. For example, graphane and graphone are hydrogenated derivatives of graphene. ...
We report the geometry, kinetic energy, and some optical properties of the 6,6,12-graphyne-based systems. We obtained the values of their binding energies and structural characteristics such as bond lengths and valence angles. Moreover, using nonorthogonal tight-binding molecular dynamics, we carried out a comparative analysis of the thermal stability of 6,6,12-graphyne-based isolated fragments (oligomer) and two-dimensional crystals constructed on its basis in a wide temperature range from 2500 to 4000 K. We found the temperature dependence of the lifetime for the finite graphyne-based oligomer as well as for the 6,6,12-graphyne crystal using a numerical experiment. From these temperature dependencies, we obtained the activation energies and frequency factors in the Arrhenius equation that determine the thermal stability of the considered systems. The calculated activation energies are fairly high: 1.64 eV for the 6,6,12-graphyne-based oligomer and 2.79 eV for the crystal. It was confirmed that the thermal stability of the 6,6,12-graphyne crystal concedes only to traditional graphene. At the same time, it is more stable than graphene derivatives such as graphane and graphone. In addition, we present data on the Raman and IR spectra of the 6,6,12-graphyne, which will help distinguish it from the other carbon low-dimensional allotropes in the experiment.
... For this reason, tuning graphene by means of hydrogenation is gaining popularity due to its distinctive properties and applications. However, the imbalance in the sublattice results in instability in free-standing graphone, which mainly arises due to the fact that carbon atoms of only one of the sublattice sheets of graphene is adsorbed by hydrogen [10]. This has prompted researchers to study hydrogen adsorption with various degrees of coverage in order to better understand the optimization of the magnetic and electronic properties for the purposes of hydrogen storage applications [11][12][13]. ...
With the incredible discovery of graphene (Gr), all of the properties studied to date suggest that it has promising applications in the development of semiconductor, spintronic, insulating, and polymer materials. However, efforts are still underway to fully understand the nature of metal–graphone(GrH) interaction in order to offer better scope for tuning the electronic and magnetic properties, which can be performed by intercalation of atoms via metal support on graphene. We chose metal atoms belonging to the s and p blocks, namely Na and Al, respectively, as the intercalating atoms. Herein, the maximum coverage of a monolayer of Na and Al was comparatively studied on a Ni(111) surface. Significant changes in the magnetic and electronic properties at the Ni(111)/graphone interface were observed upon intercalation. Of the two intercalating metal atoms, Na proved to be more effective, such that the magnetic properties of the surface Ni were only slightly decreased, and the graphone also showed better magnetic properties than in the absence of Na.
... Different results have been achieved by changing the doping amount or the adsorption position of hydrogen atoms [23][24][25][26]. For example, fully hydrogenated graphene shows a wide bandgap with annihilated Dirac points [27,28], while half-hydrogenated graphene shows anti-ferromagnetism (AFM) instead of ferromagnetism (FM) [29,30]. Moreover, it has been discussed how the band-gap opening changes under different hydrogen coverages [31]. ...
We performed first-principles calculations on two hydrogenated graphene systems with different hydrogen coverages, C8H2 and C50H2, to analyze their electronic and superconducting properties. Our results show that their electronic properties are highly correlated to the hydrogenation positions. If the two hydrogen atoms are attached to the same sublattice, the final system will be ferromagnetic. Otherwise, it will maintain nonmagnetic rather than anti-ferromagnetic. Moreover, the distance between the doped hydrogens can trigger the movement of Dirac points, which will even annihilate when the distance is close to the maximum. We further studied their superconducting properties by applying hole doping and tensile strains. The results show that the superconducting transition temperature Tc increases with more holes and reaches its maximum of about 20.2 K at the critical doping level (xc = 0.17 holes/cell). Our results show that the superconductivity mainly originates from the coupling between the out-of-plane lattice vibration modes and the electronic pz orbitals of carbon atoms. The increase of Tc can be attributed to the stronger coupling between the electrons and the low-frequency phonon. However, the application of biaxial and uniaxial tensile strain will depress the superconductivity because of the modulation of the low-frequency phonon. It is worthy to note that weak anharmonicity exists in the hydrogenated graphene systems. This work provides a systematic study on tuning the superconductivity of hydrogenated graphene.
... Previous studies [6,13] imply that Graphene as a carbon allotrope can be considered as an excellent radiation resistance enhancer in metal-Graphene NCs such as Cu-Graphene and Ni-Graphene NCs. Other allotropes of carbon such as Graphone [32,33] and Graphdiyne [34][35][36][37] can be directly used on Graphene as Graphene/Graphone [38] and Graphene/ Graphdiyne bilayers [39]. The bilayers such as Graphene/ Graphone can act in Curie temperature higher than room temperature [38]. ...
Carbon allotropes can be considered as an excellent radiation resistance enhancer in metal-Graphene nanocomposites (NCs). Many research groups studied the radiation resistance and interface stability of metal-Graphene NCs and revealed that Graphene can improve the radiation resistance of NCs under irradiation. Other allotropes of carbon have not been studied up to now. Therefore, in this work, four Cu-based NCs such as Cu-Graphene, Cu-Graphyne, Cu-Graphdiyne, and Cu-Graphane were studied by molecular dynamics (MD) to understand the role of carbon allotropes on the radiation resistance of Cu-based NCs. Compared with pure copper; four Cu-based NCs have fewer residual defects in the bulk region after irradiation. The results demonstrated that the interface of these NCs acts as a sink for radiation-induced defects, and preferentially traps interstitials over vacancies. The results of energetic calculations indicate the defect formation energy is reduced in the vicinity of interface regions. Compared with Cu-Graphyne and Cu-Graphdiyne, Cu-Graphene and Cu-Graphane have low segregation energy for interstitial emission mechanism to annihilate vacancies. Also, Cu/Graphane/Cu interface has a higher strength of interaction and attraction with vacancies due to the low value of vacancy formation energy (Evac). Thermodynamic and structural analyses reveal that Graphdiyne plane isn’t a stable plane during collision cascades. The results of this study can provide a fundamental perspective on the radiation resistance of Cu-based NCs including different carbon allotropes to select the best allotrope to improve the radiation resistance of NC for using in extreme radiation environments.
... They include SWCNT, MWCNT, graphene, graphene oxide, carbon-based supercapacitors or electrode materials, metal-free carbon catalysts derived from organic polymers, carbon quantum dots, and carbon aerogels, just to name a few. For more details, readers are referred to monographs and many excellent reviews [6][7][8][9][10][11]. Interests in discovering yet further advanced carbon materials, such as graphane, a fully hydrogenated version of graphene, and graphone, a half hydrogenated graphene [12,13] are strong. One of the common drawbacks of advanced carbon materials is the lack of mass-productive methods. ...
... Polymers 2021,13, 3775 ...
This comprehensive review article summarizes the key properties and applications of advanced carbonaceous materials obtained from polybenzoxazines. Identification of several thermal degradation products that arose during carbonization allowed for several different mechanisms (both competitive ones and independent ones) of carbonization, while also confirming the thermal stability of benzoxazines. Electrochemical properties of polybenzoxazine-derived carbon materials were also examined, noting particularly high pseudocapacitance and charge stability that would make benzoxazines suitable as electrodes. Carbon materials from benzoxazines are also highly versatile and can be synthesized and prepared in a number of ways including as films, foams, nano-fibers, nanospheres, and aerogels/xerogels, some of which provide unique properties. One example of the special properties is that materials can be porous not only as aerogels and xerogels, but as nanofibers with highly tailorable porosity, controlled through various preparation techniques including , but not limited to, the use of surfactants and silica nanoparticles. In addition to the high and tailorable porosity, benzoxazines have several properties that make them good for numerous applications of the carbonized forms, including electrodes, batteries, gas adsorbents, catalysts, shielding materials, and intumescent coatings, among others. Extreme thermal and electrical stability also allows benzoxazines to be used in harsher conditions, such as in aerospace applications.
... GYs have shown improved electronic properties and charge carriers in the optics and electronics industries. Graphone and graphane are hydrogenated forms of graphene-with fundamental band gaps of 2.45 and 5.4 eV, respectively, and interesting magnetic properties-that have shown potential for nanoelectronics and spintronics [29][30][31]. Due to structural similarities with graphene, these materials are considered to be excellent candidates for carbonaceous electronic devices, and they surely will be the subject of advanced studies for multiple and versatile applications. Scientists have been theoretically studying graphynes since the 1980s, which initially attracted attention after the discovery of fullerenes [32]. ...
Doping and its consequences on the electronic features, optoelectronic features, and magnetism of graphynes (GYs) are reviewed in this work. First, synthetic strategies that consider numerous chemically and dimensionally different structures are discussed. Simultaneous or subsequent doping with heteroatoms, controlling dimensions, applying strain, and applying external electric fields can serve as effective ways to modulate the band structure of these new sp2/sp allotropes of carbon. The fundamental band gap is crucially dependent on morphology, with low dimensional GYs displaying a broader band gap than their bulk counterparts. Accurately chosen precursors and synthesis conditions ensure complete control of the morphological, electronic, and physicochemical properties of resulting GY sheets as well as the distribution of dopants deposited on GY surfaces. The uniform and quantitative inclusion of non-metallic (B, Cl, N, O, or P) and metallic (Fe, Co, or Ni) elements into graphyne derivatives were theoretically and experimentally studied, which improved their electronic and magnetic properties as row systems or in heterojunction. The effect of heteroatoms associated with metallic impurities on the magnetic properties of GYs was investigated. Finally, the flexibility of doped GYs’ electronic and magnetic features recommends them for new electronic and optoelectronic applications.
... Further, it has been predicted that graphone possesses indirect band gap of the order of 0.46 eV, and may exhibit also magnetic properties [J. Zhou and Jena (2009) ;Feng and Zhang (2012)]. The magnetic ordering as well as the bandgap can be controlled by the hydrogenation patterns. ...
... Note that the rectangular geometry is the energetically most favoured con guration for semihydrogenated graphene (graphone). The rectangular graphone has been shown in [109] to be an AFM semiconductor with an indirect band gap of ∼2.45 eV while triangular graphone is an FM semiconductor having an indirect band gap of 0.67 eV. Unlike the tetragonal structure, a strong σ bond between C and H atoms essentially breaks the delocalisation of the π bonded network of graphene resulting in unpaired electrons responsible for the FM ground state in triangular graphone [64]. ...
Inspired by the success of graphene, various two dimensional (2D) non-hexagonal graphene allotropes having sp 2 bonded tetragonal rings in free standing (FS) (hypothetical) form and on different substrates have been proposed recently. These systems have also been fabricated after modifying the topology of graphene by chemical processes. In this review, we would like to in- dicate the role of tetra-rings and the local symmetry breaking on the structural, electronic and optical properties of the graphene system. The first principles computations have demonstrated that the tetragonal graphene (TG) allotope exhibits appreciable thermodynamic stability. The band structure of the TG nannoribbons (TGNRs) strongly depends on the size and edge geometry. This fact has been supported by the transport properties of TGNRs. The optical properties and Raman modes of this graphene allotrope have been well explored for the characterization purpose. Re- cently, a tight binding model has been used to unravel the metal to semiconductor transition under the influence of external magnetic fluxes. Even the introduction of transition metal atoms into this non-hexagonal network can control the magnetic response of the TG sheet. Furthermore, the collective effect of B-N doping and confinement effect on structural and electronic properties of TG systems have been investigated. We also suggest future directions to be explored to make the synthesis of T-graphene and its various derivatives/allotropes viable for verification of theoretical predictions. It is observed that these doped systems act as a potential candidate for carbon monox- ide (CO) gas sensing and current rectification device. Therefore, all these experimental, numerical and analytical studies related to non-hexagonal TG systems are extremely important from basic science point of view as well as for the device applications in sensing, optoelectronic and photonic devices.
... Theorists have attempted to tackle the issue of exchange coupling, with a range of predictions. [91][92][93][94][95] Ultimately, these predictions can either be validated or rendered moot only by experimental measurement; however, the hydrogenated graphene obtained by existing synthetic methods is noncrystalline. Thus, until a method is discovered for obtaining crystalline hydrogenated graphene, theoretical predictions of this type will have only limited value. ...
... 10(a) and 10(d)]. 5,85,94,95,100 These observations indicate that there should be essentially no absorption of photons less than this threshold energy. ...
Graphene’s chemical versatility is unique among two-dimensional materials. One of the simplest and most well-studied chemical modifications of graphene is hydrogenation. The electronic, optical, and mechanical properties of hydrogenated graphene can differ significantly from those of unmodified graphene, and the tunability of these properties has played a major factor in the broad interest in hydrogenated graphene throughout the scientific community. Here, the author presents a practical review of the state of the art in hydrogenated graphene research. The target audience is the researcher who is interested in working with hydrogenated graphene but lacks practical experience with the material. The author focuses on considerations of the working scientist, highlighting subtleties in preparation and characterization that are generally only gained by experience in the laboratory. In addition, the author enumerates a number of the most important categories of results concerning the properties of hydrogenated graphene. In particular, the author examines what these results mean for potential near- and long-term applications of hydrogenated graphene.
... Semi-hydrogenated derivative of graphene is called graphone [40]. Although this material is yet to be realized through experimentations [41], but theoretical calculations revealed that unhydrogenated carbon atoms in graphone couple antiferromagnetically [42], and therefore, found potential applications in magnetism, spintronix, organic ferroelectrics, molecular packing [39,43 -47] carbon sheet, resulting in a mixture of sp 2 and sp 3 hybridized carbon atoms. Upon geometry relaxation, it was found that graphone has a somewhat zigzag shape as can be seen in figure 3b [39,45]. ...
Graphene and its derivatives possess some intriguing properties, which generates tremendous interests in various fields, including biomedicine. The biomedical applications of graphene-based nanomaterials have attracted great interests over the last decade, and several groups have started working on this field around the globe. Because of the excellent biocompatibility, solubility and selectivity, graphene and its derivatives have shown great potential as biosensing and bio-imaging materials. Also, due to some unique physicochemical properties of graphene and its derivatives, such as large surface
area, high purity, good bio-functionalizability, easy solubility, high drug loading capacity, capability of easy cell membrane penetration, etc., graphene-based nanomaterials become promising candidates for bio-delivery carriers. Besides, graphene and its derivatives have also shown interesting applications in the fields of cell-culture, cell-growth and tissue engineering. In this article, a comprehensive review on the applications of graphene and its derivatives as biomedical materials has been presented. The unique properties of graphene and its derivatives (such as graphene oxide, reduced graphene oxide, graphane, graphone, graphyne, graphdiyne, fluorographene and their doped versions) have been discussed, followed by discussions on the recent efforts on the applications of graphene and its derivatives in biosensing, bio-imaging, drug delivery and therapy, cell culture, tissue engineering and cell growth. Also, the challenges involved in the use of graphene and its derivatives as biomedical materials are discussed briefly, followed by the future perspectives of the use of graphene-based nanomaterials in bioapplications. The review will provide an outlook to the applications of graphene and its derivatives, and may open up new horizons to inspire broader interests across various disciplines.
