We have studied the interaction of water and graphene doped with nitrogen in different configurations, namely, graphitic and pyridinic nitrogen, by means of the van der Waals density functional. We found that the local nitrogen configuration plays a key role in determining the stable water configuration, while the dispersion force is responsible for the water adsorption. With the graphitic nitrogen, water prefers to orient with its oxygen toward the surface, whereas for the pyridinic nitrogen it prefers to orient with its hydrogens toward the surface, because nitrogen is positively and negatively charged for the former and the latter, respectively. Our results have great implications for the modeling of the interface between water and nitrogen-doped graphitic systems.
Two-dimensional alloys of carbon and nitrogen represent an urgent interest due to prospective applications in nanomechanical and optoelectronic devices. Stability of these chemical structures must be understood as a function of their composition. The present study employs hybrid density functional theory and reactive molecular dynamics simulations to get insights regarding how many nitrogen atoms can be incorporated into the graphene sheet without destroying it. We conclude that (1) C:N=56:28 structure and all nitrogen-poorer structures maintain stability at 1000 K; (2) stability suffers from …
We report the local atomic and electronic structure of a nitrogen-doped graphite surface by scanning tunnelling microscopy, scanning tunnelling spectroscopy, X-ray photoelectron spectroscopy, and first-principles calculations. The nitrogen-doped graphite was prepared by nitrogen ion bombardment followed by thermal annealing. Two types of nitrogen species were identified at the atomic level: pyridinic-N (N bonded to two C nearest neighbours) and graphitic-N (N bonded to three C nearest neighbours). Distinct electronic states of localized π states were found to appear in the occupied and unoccup…
We show that the magnetic characteristics of Ta|CoFeB|MgO magnetic heterostructures are strongly influenced by doping the Ta underlayer with nitrogen. In particular, the saturation magnetization drops upon doping the Ta underlayer, suggesting that the doped underlayer acts as a boron diffusion barrier. In addition, the thickness of the magnetic dead layer decreases with increasing nitrogen doping. Surprisingly, the interface magnetic anisotropy increases to ~1.8 erg/cm2 when an optimum amount of nitrogen is introduced into the Ta underlayer. These results show that nitrogen doped Ta serves as …
Niobium superconducting radiofrequency cavities enable applications in modern accelerators and quantum computers. However, the surface resistance significantly deteriorates the cavities performance. Nitrogen doping surface treatment can consistently increase cavity performance by reducing surface resistance, but the improvement mechanism is not fully understood. Herein, we employed transmission electron microscopy and spectroscopy to uncover the structural and chemical differences of the Nb-air interface between the non-doped and nitrogen-doped cavities. The results indicate that nitrogen dopi…
High-quality nitrogen-doped graphene on nickel is prepared by exploiting both the catalytic properties of nickel and the solubility of nitrogen atoms into its bulk. Following the standard chemical vapor deposition procedure, a previously nitrogen-doped nickel substrate is exposed to carbon-containing precursors so that nitrogen atoms, segregating to the surface, remain trapped in the growing graphene network. Morphological and chemical characterization by scanning tunneling microscopy and X-ray photoelectron spectroscopy demonstrates that the process yields a flat, wide, continuous nitrogen-do…
We report on the formation of nitrogen-doped nanographenes containing five- and seven-membered rings by thermally induced cyclodehydrogenation on the Au(111) surface. Using scanning tunneling microscopy and supported by calculations, we investigated the structure of precursor and targets, as well as of intermediates. Scanning tunneling spectroscopy shows that the electronic properties of the target nanographenes are strongly influenced by the additional formation of non-hexagonal rings.
The magnetic state of Nitrogen-doped MgO, with N substituting O at concentrations between 1% and the concentrated limit, is calculated with density-functional methods. The N atoms are found to be magnetic with a moment of 1 Bohr magneton per Nitrogen atom and to interact ferromagnetically via the double exchange mechanism. The long-range magnetic order is established above a finite concentration of about 1.5% when the percolation threshold is reached. The Curie temperature increases linearly with the concentration, and is found to be about 30 K for 10% concentration. Besides the substitution o…
Chemical-Vapor-Deposition (CVD) diamond films were prepared using a variation of nitrogen addition into the gas source admixture by a direct current CVD method. The influence of nitrogen addition on the crystallographic texture and grain shape evolution in heteroepitaxial polycrystalline diamond films was investigated using high-resolution electron backscattering diffraction (HR-EBSD) and X-ray diffraction (XRD). The analysis reveals that an addition of 1.5% N2 to the CH4 gas flow leads to a strong enhancement of a {110} fiber texture. The phenomenon is discussed in terms of a competitive grow…
Nitrogen doped single wall carbon nanotubes have many functional benefits. Doping opens the possibility to control the electronic energy levels, surface energy, surface reactivity and charge carrier density. The additional electron in the outer shell changes the electronic properties of the nanotubes when introduced into the carbon lattice. Here we present the latest findings in the in-situ doping during synthesis of single wall carbon nanotubes using caffeine as a precursor of both carbon and nitrogen. A special furnace with two heating elements allowed us to sublimate and decompose the solid…
Having access to the chemical environment at the atomic level of a dopant in a nanostructure is crucial for the understanding of its properties. We have performed atomically-resolved electron energy-loss spectroscopy to detect individual nitrogen dopants in single-walled carbon nanotubes and compared with first principles calculations. We demonstrate that nitrogen doping occurs as single atoms in different bonding configurations: graphitic-like and pyrrolic-like substitutional nitrogen neighbouring local lattice distortion such as Stone-Thrower-Wales defects. The stability under the electron b…
Nitrogen-doped graphene was recently synthesized and was reported to be a catalyst for hydrogen dissociative adsorption under a perpendicular applied electric field (F). In this work, the diffusion of H atoms on N-doped graphene, in the presence and absence of an applied perpendicular electric field, is studied using density functional theory. We demonstrate that the applied field can significantly facilitate the binding of hydrogen molecules on N-doped graphene through dissociative adsorption and diffusion on the surface. By removing the applied field the absorbed H atoms can be released effi…
Graphene has vast promising applications on the nanoelectronics and spintronics because of its unique magnetic and electronic properties. Making use of an ab initio spin-polarized density functional theory, implemented by the method of Heyd-Scuseria-Ernzerhof 06(HSE06) hybrid functional, the properties of nitrogen substitutional dopants in semi-metal monolayer graphene were investigated. We found from our calculation, that introducing nitrogen doping would possibly break energy degeneracy with respect to spin(spin symmetry breaking) at some doping concentrations with proper dopant configuratio…
Using the ab initio FLAPW-GGA method we examine the electronic and magnetic properties of nitrogen-doped non-magnetic sesquioxide La2O3 emphasizing the role of doping sites in the occurrence of d0-magnetism. We predict the magnetization of La2O3 induced by nitrogen impurity in both octahedral and tetrahedral sites of the oxygen sublattice. The most interesting results are that (i) the total magnetic moments (about 1 μB per supercells) are independent of the doping site, whereas (ii) the electronic spectra of these systems differ drastically: La2O3:N with six-fold coordinated nitrogen behaves a…
Fullerene-based materials including C60 and doped C60 have previously been proposed as anodes for lithium ion batteries. It was also shown earlier that n- and p-doping of small molecules can substantially increase voltages and specific capacities. Here, we study ab initio the attachment of multiple lithium atoms to C60, nitrogen-doped C60 (n-type), and boron doped C60 (p-type). We relate the observed attachment energies (which determine the voltage) to changes in the electronic structure induced by Li attachment and by doping. We compare results with a GGA functional and a hybrid functional an…
Utilizing the strengths of nitrogen doped graphene quantum dot (N-GQD) as a substrate, here in, we have shown that one can stabilize the catalytically more active planar Au 20 (P-Au 20 ) compared to the thermodynamically more stable tetrahedral structure (T-Au 20 ) on an N-GQD. Clearly, this simple route avoids the usage of traditional transition metal oxide substrates which have been suggested and used for stabilizing the planar structure for a long time. Considering the experimental success in the synthesis of N-GQDs and in the stabilization of Au nanoparticles on N-doped graphene, we expect…
For a nitrogen dimer in insulating MgO, a ferromagnetic coupling between spin-polarized $2p$-holes is revealed by calculations based on the density functional theory amended by an on-site Coulomb interaction and corroborated by the Hubbard model. It is shown that the ferromagnetic coupling is facilitated by a T-shaped orbital arrangement of the $2p$-holes, which is in its turn controlled by an intersite Coulomb interaction due to the directionality of the $p$-orbitals. We thus conjecture that this interaction is an important ingredient of ferromagnetism in band insulators with $2p$ dopants.
In this paper, we have analysed the electronic and mechanical properties of Nitrogen(N) doped (6,1) SWCNTs based on first-principles and Molecular dynamic (MD) simulation. A schematic N-doping on SWCNT was performed along zigzag(zz) and armchair(ac) direction. Armchair doping is considered parallel to the tube axis while the zigzag is along the cross-section perpendicular to the tube axis. In doping pattern (both zz and ac) we have observed the variation in electronic properties for even number of N-doping and odd number of N-doping. To study the mechanical properties we have adopted ab-initio…
A finite Schottky barrier and large contact resistance between monolayer MoS2 and electrodes are the major bottlenecks in developing high-performance field-effect transistors (FETs) that hinder the study of intrinsic quantum behaviors such as valley-spin transport at low temperature. A gate-tunable graphene electrode platform has been developed to improve the performance of MoS2 FETs. However, intrinsic misalignment between the work function of pristine graphene and the conduction band of MoS2 results in a large threshold voltage for the FETs, because of which Ohmic contact behaviors are obser…
High Curie temperature of 900 K has been reported in Cr-doped AlN diluted magnetic semiconductors prepared by various methods, which is exciting for spintronic applications. It is believed that N defects play important roles in achieving the high temperature ferromagnetism in good samples. Motivated by these experimental advances, we use a full-potential density-functional-theory method and supercell approach to investigate N defects and their effects on ferromagnetism of (Al,Cr)N with N vacancies (V_N). Calculated results are in agreement with experimental observations and facts of real Cr-do…
The heat capacity Cm of polycrystalline fullerite C60 doped with nitrogen has been measured in the temperature interval 2 - 13 K. The contributions to heat capacity from translational lattice vibrations (Debye contribution), orientational vibrations of the C60 molecules (Einstein contribution) and from the motion of the N2 molecules in the octahedral cavities of the C60 lattice have been estimated. However, we could not find (beyond the experimental error limits) any indications of the first - order phase transformation that had been detected earlier in the dilatometric investigation of the or…
Defect configuration, not nitrogen content, governs the mechanical integrity of nitrogen-doped graphene: a molecular dynamics study
The University of Alabama in Huntsville（阿拉巴马大学亨茨维尔分校）；University of Illinois Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；Bangladesh University of Engineering and Technology（孟加拉工程技术大学）
We report accurate energetics of defects introduced in GaN on doping with divalent metals, focussing on the technologically important case of Mg doping, using a model which takes into consideration both the effect of hole localisation and dipolar polarisation of the host material, and includes a well-defined reference level. Defect formation and ionisation energies show that divalent dopants are counterbalanced in GaN by nitrogen vacancies and not by holes, which explains both the difficulty in achieving p-type conductivity in GaN and the associated major spectroscopic features, including the …
Using Density functional theory (DFT) in conjunction with a solvation model we have investigated the phenomenon of eletrode-electrolyte interaction at the electrode surface and its consequences on the electrochemical properties like the charge storage and total capacitance of doped and substituted oxygen functionalised Ti$_{3}$C$_{2}$ supercapcitor electrode. We have studied nitrogen doped, nitrogen substituted and molybdenum substituted Mxenes in acidic electrolyte H$_{2}$SO$_{4}$ solution. By considering nitrogen doping at different sites, we found that the greatest capacitance is obtained f…
In the present work we study the effect of nitrogen (N) and fluorine (F) doping in the electronic properties of ZrO$_2$ by using \emph{ab initio} electronic structure calculations. Our calculations show the importance of on-site Coulomb correlation in estimating the correct band gap of ZrO$_2$. The N and F doping provide hole and electron type impurity states in the band gap closer to the top of the valance band and bottom of the conduction band, respectively. The formation of such impurity states may be exploited in fabricating a $p$-$n$ junction expected to be useful in making an ultraviolet…
Graphitic nitrogen-doped graphene is an excellent platform to study scattering processes of massless Dirac fermions by charged impurities, in which high mobility can be preserved due to the absence of lattice defects through direct substitution of carbon atoms in the graphene lattice by nitrogen atoms. In this work, we report on electrical and magnetotransport measurements of high-quality graphitic nitrogen-doped graphene. We show that the substitutional nitrogen dopants in graphene introduce atomically sharp scatters for electrons but long-range Coulomb scatters for holes and, thus, graphitic…
Two-dimensional graphene exhibits many fascinating properties such as ballistic electronic conduction and quantum Hall effect at room temperature.1-4 Graphene doped electrochemically or through charge-transfer with electron-donor and -acceptor molecules,5-7 shows marked changes in electronic structure, with characteristic signatures in the Raman spectra.5-10 Substitutional doping, universally used in tuning properties of semiconductors, could be a powerful tool to control the electronic properties of graphene. Here, we present the structure and properties of boron and nitrogen doped graphenes,…
Active sites and catalytic mechanism of nitrogen-doped graphene in oxygen reduction reaction (ORR) have been extensively studied but are still inconclusive, partly due to the lack of an experimental method that can detect the active sites. It is proposed in this report that the active sites on nitrogen-doped graphene can be determined via the examination of its chemical composition change before and after ORR. Synchrotron-based X-ray photoelectron spectroscopy analyses of three nitrogen-doped multilayer graphene samples reveal that oxygen reduction intermediate OH(ads) which should chemically …
Sulfur and nitrogen dual doped graphene have been extensively investigated in the field of oxygen reduction reaction, supercapacitors and batteries, but their magnetic and absorption performance have not been explored. Besides, the effects of doping sequence of sulfur and nitrogen atoms on the morphology, structural property and the corresponding microwave absorption performance of the dual doped graphene remain unexplored. In this work, nitrogen and sulfur dual doped graphene with different doping sequence were successfully prepared using a controllable two steps facile thermal treatment meth…
This study investigates the photocatalytic nitrogen fixation on a cation-doped surface (Bi$_{x}$M$_{y}$)$_2$MoO$_6$ where (M = Fe, La, Yb) in both the orthorhombic and monoclinic configurations using a density functional theory (DFT) approach with experimentally validated model inputs. The proceeding discussion focuses on the Heyrovsky-type reactions for both the associative and dissociative reaction pathway related to nitrogen reduction. Key fundamental insight in the reduction mechanism is discussed that relates the material properties of the substitutional ions to the nitrogen and hydrogen …
Density functional theory with local spin density approximation has been used to propose possible room temperature ferromagnetism in N-doped NaCl-type BaO. Pristine BaO is a wide bandgap semiconductor, however, N induces a large density of states at the Fermi level in the nonmagnetic state, which suggests magnetic instability within the Stoner mean field model. The spin-polarized calculations show that N-doped BaO is a true half- metal, where N has a large magnetic moment, which is mainly localized around the N atoms and a small polarization at the O sites is also observed. The origin of magne…
Warsaw University of Technology（华沙理工大学）；Lublin University of Technology（卢布林理工大学）；BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park（BCMaterials，巴斯克材料、应用和纳米结构中心，UPV/EHU科学园）；Ikerbasque, Basque Foundation for Science（Ikerbasque，巴斯克科学基金会）；Cranfield University（克兰菲尔德大学）
Using microwave-assisted plasma chemical vapour deposition (CVD) a layer of Nitrogen doped ultra-nano-crystalline diamond (N-UNCD) is deposited on top of a non-conducting diamond layer, which itself is situated on a Silicon wafer. This structure is then shaped into Hall-bar devices of various dimensions using optical lithography and dry-etching techniques. The devices' electrical properties are investigated at various temperatures using a cryogen-free dilution refrigerator.
We report the first experimental observation of a doubly-charged defect in diamond, SiV2-, in silicon and nitrogen co-doped samples. We measure spectroscopic signatures we attribute to substitutional silicon in diamond, and identify a silicon-vacancy complex decorated with a nearest-neighbor nitrogen, SiVN, supported by theoretical calculations. Samples containing silicon and nitrogen are shown to be heavily photochromic, with the dominant visible changes due to the loss of SiV0/- and gain in the optically-inactive SiV2-.
Based on first principles density functional theory calculations we explored energetics of oxygen reduction reaction over pristine and nitrogen-doped graphene with different amounts of nitrogen doping. The process of oxygen reduction requires one more step then same reaction catalyzed by metals. Results of calculations evidence that for the case of light doped graphene (about 4% of nitrogen) energy barrier for each step is lower than for the same process on Pt surface. In contrast to the catalysis on metal surface the maximal coverage of doped graphene is lower and depends on the corrugation o…
A significant advance toward achieving practical applications of graphene as a two-dimensional material in nanoelectronics would be provided by successful synthesis of both n-type and p-type doped graphene. However reliable doping and a thorough understanding of carrier transport in the presence of charged impurities governed by ionized donors or acceptors in the graphene lattice are still lacking. Here we report experimental realization of few-layer nitrogen-doped (N-doped) graphene sheets by chemical vapor deposition of organic molecule 1, 3, 5-triazine on Cu metal catalyst. By reducing the …
Self-organized V-N co-doped TiO2 nanotube arrays (TNAs) with various doping amount were synthesized by anodizing in association with hydrothermal treatment. Impacts of V-N co-doping on the morphologies, phase structures, and photoelectrochemical properties of the TNAs films were thoroughly investigated. The co-doped TiO2 photocatalysts show remarkably enhanced photocatalytic activity for the CO2 photoreduction to methane under ultraviolet illumination. The mechanism of the enhanced photocatalytic activity is discussed in detail.
Samples of nitrogen-doped titanium dioxide (anatase, $0.2 \leq N \leq 1.0~wt\%$) prepared by the sol-gel method were investigated using X-band EPR spectroscopy, photoconductivity and photocatalysis measurements. $N\bullet$ and $NO\bullet$ paramagnetic defects in N-TiO2 have been observed; their concentrations and spin-Hamiltonian parameters were calculated. An increase both in the rate of the generation of free charge carriers and in the rate of photocatalysis was found in N-TiO2 in contrast with non-doped titania under visible light. The correlation of the density of the observed radicals wit…
II-oxide and III-nitride semiconductors doped by nonmagnetic 2p light elements are investigated as potential dilute magnetic semiconductors (DMS). Based on our first-principle calculations, nitrogen doped ZnO, carbon doped ZnO, and carbon doped AlN are predicted to be ferromagnetic. The ferromagnetism of such DMS materials can be attributed to a p-d exchange-like p-p coupling interaction which is derived from the similar symmetry and wave function between the impurity (p-like t_2) and valence (p) states. We also propose a co-doping mechanism, using beryllium and nitrogen as dopants in ZnO, to …
Nanocomposite metal oxide thin films exhibit assuring qualities in the field of gas sensors because of the collective opportunities provided by the heterointerface formation. In this work, we present the synthesis of nitrogen doped mesoporous In$_2$O$_3$-ZnO nano-composite thin films by simple wet chemical method using urea as the nitrogen precursor. SEM investigation suggests formation of mesoporous nano-composite thin films, where the uniformity of surface pore distribution depends on the relative proportion of In$_2$O$_3$ and ZnO in the composites. HRTEM investigation suggest formation of s…
First principle modeling of nitrogen- and boron-doped phosphorene demonstrates the tendency toward formation of highly ordered structures. Nitrogen doping leads to the formation of -N-P-P-P-N- lines. Further transformation to -P-N-P-N- lines across the chains of phosphorene occurs with increasing band gap and increasing nitrogen concentration, which coincides with the decreasing chemical activity of N-doped phosphorene. In contrast to the case of nitrogen, boron atoms prefer to form -B-B- pairs with the further formation of -P-P-B-B-P-P- patterns along the phosphorene chains. The low concentra…
We report depth-resolved photoluminescence measurements of nitrogen-vacancy (NV$^-$) centers formed along the tracks of swift heavy ions (SHIs) in type Ib synthetic single crystal diamonds that had been doped with 100 ppm nitrogen during crystal growth. Analysis of the spectra shows that NV$^-$ centers are formed preferentially within regions where electronic stopping processes dominate and not at the end of the ion range where elastic collisions lead to formation of vacancies and defects. Thermal annealing further increases NV yields after irradiation with SHIs preferentially in regions with …
The hybrid nanostructures of nitrogen doped carbon materials and nonprecious transition metals are among the most promising electrocatalysts to replace noble metal catalysts for renewable energy applications. However, the fundamental principles governing the catalytic activity of such hybrid materials remain elusive. Herein, we systematically explore the electrocatalytic properties of transition metals, transition metal oxides and carbides substrates covered by nitrogen-doped graphitic sheets for hydrogen evolution reaction (HER). Our first-principles calculations show that the graphitic sheet…
Prompted by recent reports on $\sqrt{3} \times \sqrt{3}$ graphene superlattices with intrinsic inter-valley interactions, we perform first-principles calculations to investigate the electronic properties of periodically nitrogen-doped graphene and carbon nanotube nanostructures. In these structures, nitrogen atoms substitute one-sixth of the carbon atoms in the pristine hexagonal lattices with exact periodicity to form perfect $\sqrt{3} \times \sqrt{3}$ superlattices of graphene and carbon nanotubes. Multiple nanostructures of $\sqrt{3} \times \sqrt{3}$ graphene ribbons and carbon nanotubes ar…
First-principles molecular dynamics (FPMD) simulations are performed on 6 and 12% Na in dense liquid N. A detailed description of structural and electronic properties leading to an understanding of the effect of Na-doping on the polymerization phase transition of N is presented. Compression of the mixtures from 5 to 90 GPa shows three distinct regions of characteristic local order separated by pressures near 30 and 65 GPa. Computation of Gibbs free energies of mixing shows that these mixtures are thermodynamically stable beyond 20 and 15 GPa for 6 and 12 % Na respectively.
Photocatalytic nitrogen fixation from air directly under sunlight can contribute significantly to carbon neutralization. It is an ideal pathway to replace the industrial Haber Bosch process in future. A Fe-doped layered WO$_3$ photocatalyst containing oxygen vacancies was developed which can fix nitrogen from air directly under sunlight at atmospheric pressure. The iron doping enhances the transport efficiency of photogenerated electrons. The photocatalytic efficiency is around 4 times higher than that of pure WO$_3$. The optimum nitrogen fixation conditions were examined by orthogonal experim…
We study the possibility of d0 ferromagnetism in the compound MgO doped with nitrogen (N). The Haldane-Anderson impurity model is formulated within the tight-binding approximation for determining the host band-structure and the impurity-host hybridization. Using the quantum Monte Carlo technique, we observe a finite local moment for an N impurity, and long-range ferromagnetic correlations between two N impurities. The ferromagnetic correlations are strongly influenced by the impurity bound state. When the ferromagnetic correlation between a pair of impurities is mapped onto the isotropic Heise…
In the present work, we systematically studied the effect of Al doping on the phase formation of iron nitride (Fe-N) thin films. Fe-N thin films with different concentration of Al (Al=0, 2, 3, 6, and 12 at.%) were deposited using dc magnetron sputtering by varying the nitrogen partial pressure between 0 to 100%. The structural and magnetic properties of the films were studied using X-ray diffraction and polarized neutron reflectivity. It was observed that at the lowest doping level (2 at.% of Al), nitrogen rich non-magnetic Fe-N phase gets formed at a lower nitrogen partial pressure as compare…
Photocatalytic water splitting is a promising renewable energy source as an alternative for limited fossil fuels. The effectiveness of the conversion from solar energy to hydrogen fuel relies primarily on the material. Previously, researchers studied different TMDs such as WS$_{2}$, and PdSe$_{2}$. These materials perform well in certain aspects such as strong adsorption stability and promising abilities for HER, however, their band gaps are still not ideal. In this paper, we studied a new TMD material WSe$_{2}$, which is currently used in heterostructure photocatalysts. To our knowledge, this…
Novel uses for 2-dimensional materials like graphene and hexagonal boron nitride (h-BN) are being frequently discovered especially for membrane and catalysis applications. Still however, a great deal remains to be understood about the interaction of environmentally and industrially elevant molecules such as water with these materials. Taking inspiration from advances in hybridising graphene and h-BN, we explore using density functional theory, the dissociation of water, hydrogen, methane, and methanol on graphene, h-BN, and their isoelectronic doped counterparts: BN doped graphene and C doped …
Hydrogen Storage on Transition-Metal-Decorated Nitrogen-Modified Carbon Nanoribbons
University of New England（新英格兰大学）；Karpagam Academy of Higher Education（卡尔帕甘高等教育学院）；Bhabha Atomic Research Centre（巴哈原子研究中心）；Homi Bhabha National Institute（霍米·巴巴国立研究所）；University of Canberra（堪培拉大学）；The University of Queensland（昆士兰大学）
The interaction between substitutional nitrogen atoms in graphene is studied by performing first principles calculations. The nearest neighbor interaction between nitrogen dopants is highly repulsive because of the strong electrostatic repulsion between nitrogen atoms, which prevents the full phase separation in nitrogen doped graphene. Interestingly, there are two relatively stable nitrogen-nitrogen pairs due to the anisotropy charge redistribution induced by nitrogen doping. We reveal two stable semiconducting ordered N doped graphene structures C3N and C12N through the cluster expansion tec…
