Hexagonal Carbon Rings Research Articles

Automated image acquisition and analysis of graphene and hexagonal boron nitride from pristine to highly defective and amorphous structures

Defect-engineered and even amorphous two-dimensional (2D) materials have recently gained interest due to properties that differ from their pristine counterparts. Since these properties are highly sensitive to the exact atomic structure, it is crucial to be able to characterize them at atomic resolution over large areas. This is only possible when the imaging process is automated to reduce the time spent on manual imaging, which at the same time reduces the observer bias in selecting the imaged areas. Since the necessary datasets include at least hundreds if not thousands of images, the analysis process similarly needs to be automated. Here, we introduce disorder into graphene and monolayer hexagonal boron nitride (hBN) using low-energy argon ion irradiation, and characterize the resulting disordered structures using automated scanning transmission electron microscopy annular dark field imaging combined with convolutional neural network-based analysis techniques. We show that disorder manifests in these materials in a markedly different way, where graphene accommodates vacancy-type defects by transforming hexagonal carbon rings into other polygonal shapes, whereas in hBN the disorder is observed simply as vacant lattice sites with very little rearrangement of the remaining atoms. Correspondingly, in the case of graphene, the highest introduced disorder leads to an amorphous membrane, whereas in hBN, the highly defective lattice contains a large number of vacancies and small pores with no indication of amorphisation. Overall, our study demonstrates that combining automated imaging and image analysis is a powerful way to characterize the structure of disordered and amorphous 2D materials, while also illustrating some of the remaining shortcomings with this methodology.

Mechanical properties of TPDH-graphene: atomistic aspect

Abstract TPDH-graphene is a new type of two-dimensional carbon material predicted by first-principles calculations to have tetragonal (T), pentagonal (P), decagonal (D) and hexagonal (H) carbon ring structures. First-principles calculations show that this special structure gives it excellent mechanical properties and promising applications in nanoelectronics. In this paper, a comprehensive test of its mechanical properties was carried out using the classical molecular dynamics (MD), mainly exploring the effects of factors such as tensile direction and temperature on its mechanical properties, and exploring the effects of introducing rectangular and circular defects on its mechanical properties. The results show that: TPDH-graphene exhibits significant anisotropy in zigzag and armchair directions, and the material exhibits some tensile toughness in armchair direction; the mechanical properties of the material are weakened at higher temperatures; the adding of defects leads to the reduction of the mechanical properties of the material in different directions to different degrees, and the The tensile toughness in the armchair direction is weakened by the addition of defects.

Evolution from Topological Nodal Points to Nodal Line: Realized in Fused Carbon Allotrope

Herein, via first‐principle calculations and theoretical analysis, a new Dirac semimetal carbon system called C32, which is composed of pentagonal, hexagonal, heptagonal, and octagonal carbon rings is systematically investigated. The stability of C32 is verified by calculating the phonon dispersion, elastic constants, etc., and an appropriate pathway for experimental synthesis is proposed. Besides, it is discovered that the system holds the quadruple rotation and inversion symmetry, resulting in the emergence of eight twisted Dirac cones (D1 and D2) with a highly anisotropic Fermi velocity from 3.83 × 105 to 8.96 × 105 m s−1 along different k directions. To substantiate the semimetallic nature of C32, its nontrivial topological properties are confirmed through the presence of topologically protected edge states, and the nonzero ℤ2 topological invariant. More importantly, by introducing biaxial strain, it is uncovered that Dirac cones can gradually evolve into a nodal line, and the perfect nodal line can be obtained when the biaxial strain is 13.3%. Furthermore, by constructing the tight‐binding model, the appearance of the Dirac cone is perfectly repeated and its evolution into the nodal line under biaxial strain is explained.

Insights into the DHQ-BN: mechanical, electronic, and optical properties

Computational materials research is vital in improving our understanding of various class of materials and their properties, contributing valuable information that helps predict innovative structures and complement empirical investigations. In this context, DHQ-graphene recently emerged as a stable two-dimensional carbon allotrope composed of decagonal, hexagonal, and quadrilateral carbon rings. Here, we employ density functional theory calculations to investigate the mechanical, electronic, and optical features of its boron nitride counterpart (DHQ-BN). Our findings reveal an insulating band gap of 5.11 eV at the HSE06 level and good structural stability supported by phonon calculations and ab initio molecular dynamics simulations. Moreover, DHQ-BN exhibits strong ultraviolet (UV) activity, suggesting its potential as a highly efficient UV light absorber. Its mechanical properties, including Young’s modulus (230 GPa) and Poisson’s ratio (0.7), provide insight into its mechanical resilience and structural stability.

Molecular dynamics simulation of effect of nickel transition layer on deposition of carbon atoms and graphene growth on cemented carbide surfaces

<sec>WC-Co cemented carbide has excellent cutting performance, which is a potential tool material. But when it is used as cutting ultra-high strength and high hardness materials, the machining accuracy and service life of the tool are significantly reduced. Graphene is a potential coating material for cemented carbide cutting tools due to its excellent mechanical properties. In this work, molecular dynamics (MD) is used to simulate the deposition of nickel transition layer and high-temperature catalytic growth of graphene in cemented carbide. The Ni and C atomic deposition process and the high temperature annealing process are simulated, and a combination of potential functions is adopted to continuously simulate these two deposition processes. The effect of deposition temperature and the effect of incident energy on the growth of graphene are analyzed. The healing mechanism of nickel-based catalytic defective graphene under high-temperature annealing is explored in detail.</sec><sec>The simulation results show that at the deposition temperature of 1100 K, the coverage of graphene is higher and the microstructure is flat. The higher temperature helps to provide enough kinetic energy for carbon atoms to overcome the potential energy barrier of nucleation, thereby promoting the migration and rearrangement of carbon atoms and reducing graphene growth defects. Too high a temperature will lead to continuous accumulation of carbon atoms on the deposited carbon rings, forming a multilayered reticulation and disordered structure, which will cause a low coverage rate of graphene. The increase of incident energy helps to reduce the vacancy defects in the film, but excessive energy leads to poor continuity of the film, agglomeration, the more obvious stacking effect of carbon atoms and the tendency of epitaxial growth. When the incident energy is 1 eV, the surface roughness of the film is lower, and more monolayer graphene can be grown. During annealing at 1100 K, the carbon film dissolves and nucleates simultaneously in the Ni transition layer, and the nickel transition layer catalyzes the repair of defective graphene. The graphene film becomes more uniform, and the number of hexagonal carbon rings increases. Appropriate high-temperature annealing can help to repair and reconstruct defective carbon rings and rearrange carbon chains into rings. Therefore, when the deposition temperature is 1100 K and the incident energy is 1 eV, graphene can be deposited and annealed to grow a high-quality graphene coatings. The simulation results provide the reference for preparing the cemented carbide graphene coated tools.</sec>

Theoretical prediction of metallic R12-graphene as a promising anode material for potassium-ion batteries with high ion mobility, high capacity, and excellent electrolyte wettability

Although graphene has excellent electrical and mechanical properties, the giant delocalized π-electron system makes it chemically inert. Here, we propose an idea to design two-dimensional (2D) carbon allotropes via incorporating multiple rings in sp2-hybridized carbon networks, which can break the π-bonding network and enhance the surface reactivity. By assembling molecule of cyclobut(a)acenaphthylene, we predict a monolayer 2D carbon material, named as R12-graphene, which is composed of quadrilateral, pentagonal, hexagonal, and dodecagonal carbon rings. It shows great stability in energetic, dynamic, thermodynamic, and mechanical aspects. It exhibits high-performance as an anode material for potassium-ion batteries (PIBs), including an intrinsic metallic behavior, a high theoretical capacity (632 mA h g−1), a low K diffusion barrier (0.33 eV), and a low average open-circuit voltage (0.5 V). The presence of electrolytes can provide better K ion adsorption and diffusion capability compared to that in vacuum. Furthermore, R12-graphene has excellent wettability toward some commonly used electrolytes, which is beneficial for improving the charge/discharge rate for PIBs.

Self-assembled CoS/S-rGO dual-functional composite, and reliable hydrogen evolution performance in both acidic and alkaline media

Developing an amphoteric-functional hydrogen evolution electrode that is useable in both acidic and alkaline electrolytes is an innovative future energy strategy. Here, CoS/S-rGO/CP electrode is obtained by direct hydrothermal growth of CoS loaded on S-rGO onto carbon paper (CP). The introduction of S reduces defects in the hexagonal carbon rings in rGO. CoS/S-rGO/CP electrode is slightly more stable in acidic one (0.5 M H2SO4) than in alkaline (1.0 M KOH) electrolytes. This is because S ion elution from CoS or S-rGO is suppressed due to the presence of SO42− ion, a common ion, in the acid electrolyte. Gibbs free energy calculations suggest that the overall rate in the alkaline electrolyte is thermodynamically slightly slower than in the acidic electrolyte due to the lower H∗ coverage. In CoS/S-rGO/CP, S in S-rGO donates electrons to Co2+ in CoS, while S in CoS repels electrons to C=S in S-rGO, resulting in there is a strong synergy between CoS and S-rGO. Eventually, CoS/S-rGO/CP electrode exhibits faradaic efficiencies of 97.85% and 97.01% in acidic and alkaline electrolytes with overpotentials of −0.20 and −0.22 V, and Tafel slopes of 89.2 and 96.1 mV dec−1, respectively. In particular, the electrode performs almost as well as commercial Pt/CP under the same reaction conditions, highlighting its future commercialization prospects as a noble-metal-free HER electrode.

A New Structure with Localized sp2 Bonding for Fivefold Twinning in Diamond.

Changes in atomic bonding configuration in carbon from sp3 to sp2 are known to exist in certain structural defects in diamond, such as twin boundaries, grain boundaries, and dislocations, which have a significant impact on many properties of diamond. In this work, the atomic structure of fivefold twinning in detonation synthesized ultra-dispersed diamonds is investigated using a combination of techniques, including spherical aberration-corrected high-resolution electron microscopy (HREM), HREM image simulations, and molecular mechanics (MM) calculations. The experimental HREM images reveal clearly that the fivefold twinning in diamond has two distinct structures. In addition to the concentric fivefold twins, where the core structure is the intersection of five {111} twinning boundaries, a new extended core structure with co-hybridization of bonding is identified and analyzed in fivefold twinning. The atomic structure forming these fivefold twinning boundaries and their respective core structures is proposed to involve both the tetrahedral sp3 and planar graphitic sp2 bonding configurations, in which a co-hybridized planar hexagon of carbon serves as a fundamental structural unit. The presence of this sp2 -bonded planar unit of hexagonal carbon rings in general grain boundaries is also discussed.

A new carbon allotrope: Biphenylene as promising anode materials for Li-ion and Li[sbnd]O2 batteries

Using first-principles computational approaches, we investigate a new carbon allotrope, biphenylene, composed of tetragonal, hexagonal, and octagonal carbon rings as a promising material for Li-ion and LiO2 batteries. We find the Li/C ratio is <1/6 for the single-layer biphenylene which is similar to that of graphene. However, it can reach to lithium composition of Li1C6, Li1C4.5, Li1C4, Li1C3.75, and Li1C3 for bi-, tri-, tetra-, penta-layer, and bulk biphenylene, respectively. It is also found that Li is very mobile on both single-layer and bi-layer biphenylene based on the calculation results of the interaction between Li and substrate and Li diffusion. In addition, we also elucidate the electrochemical performance via the discharge−charge mechanism using Li/biphenylene as electrocatalyst materials of LiO2 battery. Gibbs free energy diagram of the discharge-charge mechanism is illustrated to examine the electrochemical performance. Our results reveal that biphenylene network can be a promising and low-cost catalyst for both Li-ion and LiO2 batteries.

PO-C32: A two-dimensional graphene-based membrane for efficient seawater desalination

Freshwater shortage has become a looming global crisis with consistent population growth, industrialization, and climate variability, and desalination is regarded as a promising solution. Two-dimensional (2D) crystalline materials are valued for their excellent molecular permeability and selectivity. However, most of the reported desalination membranes suffer from high contamination tendency and a limitation of permeability-selectivity trade-off. In this work, we screened a 2D graphene-based nanomaterial (PO-C32) consisting of dodecagonal, octagonal, hexagonal, and pentagonal carbon rings by density functional theory (DFT) and machine learning (ML). The results show that the periodic pores of 0.55 nm ensure the material achieves nearly 100 % desalination efficiency. The most optimal Na adsorption is located at the hollow site of the dodecagonal ring, and the strong adsorption ability provides the membrane with satisfactory salt ions rejection. The suitable pore density and homogeneity enhance anti-pressure stability, mechanical stability, and service life. In addition, inherent interlinked electron structure produces a self-cleaning effect that contributes to recycling. These features endow PO-C32 with great potential as desalination membrane, providing a promising candidate idea for efficient and low-energy desalination technology.

Electronic-level deciphering of the desalination mechanism of high-performance graphenylene membranes

The insufficiency of available freshwater has surged as a major global concern in recent years, and the issue is raising ever more awareness. Meanwhile, the recent experimental synthesis of graphenylene has inspired researchers to pursue its applicative merits. The related properties regarding lithium-ion storage electrodes and gas separation membranes of graphenylene have been reported. However, the suitability of graphenylene as a desalination membrane has yet to be fully established. In the present study, with a view to delineating the action mechanism of graphenylene desalination membrane, we have dissected its structure and properties through first-principles and molecular dynamics. The results illustrate that graphenylene comprising dodecagonal, hexagonal, and tetragonal carbon rings contains 0.55 nm nanopores, which should permit outstanding desalination properties. In addition, the periodic pore distribution should support stress dispersion in service to preserve membrane integrity. The low water-molecule free-energy barrier, remarkable salt ion adsorption properties, and favorable anti-agglomeration ability endow graphenylene with desirable permeability and selectivity. Furthermore, we demonstrate that graphenylene is a 2D Dirac semi-metallic material. The interlinked electronic structure of which confers it with self-cleaning behavior, facilitating the restoration of water flux. The present research has elucidated the mechanism whereby effective desalination may be achieved on graphenylene membranes. Further, it has clarified the potential applicability of such membranes. They show good prospects for the advancement of seawater desalination technology.

Phosphorus and nitrogen codoped entangled carbon nanotubes forming spongy materials: Synthesis and characterization

Carbon sponges are of great interest of the scientific community given their potential in advanced applications such as water cleaning, catalysis, energy storage, and mechanical reinforcement. These carbon nanomaterials improve their attributes for unexpected properties and applications by doping with foreign atoms. Nitrogen‑phosphorus-codoped and functionalized carbon nanotube sponges (NP-CNTSs) were synthesized, using the aerosol-assisted chemical vapor deposition (AACVD) method. We used acetonitrile and triphenylphosphine (TPP) as nitrogen and phosphorus precursors. According to our results, the NP-CNTSs were formed by entangled multi-walled carbon nanotubes (MWCNTs) of diameters ranging between 60 and 300 nm with Fe2P and Fe3C nanoparticles in the walls and inside the carbon nanotube sponges (CNTSs) respectively. The Fourier transform infrared (FTIR) characterization revealed the vibrational modes of aromatic and aliphatic CH, PO, PH, and OCN bonds. The NP-CNTSs undergo a quasi-reversible hydroquinone/quinone redox process as revealed by cyclic voltammetry studies. They also efficiently retain organic solvents, absorbing up to 40 times their weight for dichlorobenzene. The XPS and Raman characterizations show the presence of pyridinic nitrogen, which might be responsible for the formation of cavities in the wall of the CNTSs and the entanglement of carbon nanotubes, which promotes the growth of the NP-CNTSs. To study the role of nitrogen and phosphorus in the electronic properties of carbon materials, we carried out calculations proposed in the density functional theory (DFT) for phosphorus‑nitrogen codoping bilayer graphene and carbon nanotube junctions containing pentagonal, hexagonal, and heptagonal carbon rings.

Biphenylene: A Two-Dimensional Graphene-Based Coating with Superior Anti-Corrosion Performance.

Metal corrosion can potentially cause catastrophic engineering accidents threatening personal safety; thus, coating protection is a tremendously valuable anti-corrosion initiative. Recently, biphenylene, a novel two-dimensional (2D) graphene-based material, has achieved a remarkable synthetic breakthrough; the anti-corrosion properties of biphenylene, with its specific pore structure, are predicted to be beneficial in applications of metal corrosion resistance. In this study, the anti-corrosion mechanism of biphenylene is deciphered utilizing first principles and molecular dynamics. The results suggest that biphenylene with tetragonal, hexagonal, and octagonal carbon rings supplies adequate sites for stable O atom adsorption. The charge transfer amounts of +0.477 and +0.420 e facilitate the formation of a compact oxygen-rich layer on the material surface to acquire outstanding anti-corrosion properties. The moderate wettability of biphenylene prevents the water-based solution from encroaching on the biphenylene coating and substrate. In addition, the intensive binding between biphenylene and the aluminum substrate strengthens the integration of the two heterogeneous structures with −413.7 and 415.5 eV, which guarantees the durable application of biphenylene coating.

ZW-21: A novel two-dimensional graphene-based anode material for the lithium-ion battery

Recently, many efforts have been made to explore advanced anode materials for lithium-ion batteries. However, developing anode materials for lithium-ion batteries with excellent cycling, mechanical, and electronic properties remains a challenge. Herein, a novel two-dimensional (2-D) carbon anode material (named ZW-21) is searched using first principles, which consists of a regular arrangement of octagonal, hexagonal, and pentagonal carbon rings. The results imply that ZW-21 possesses a satisfactory capacity (634 mAh·g−1) and very impressive ionic conductivity (0.345 eV) compared with graphene. This is due to the adsorption structure of the 8-membered ring being more stable, the diffusion rate of the 5-membered ring being more efficient, and the 8–5–6-membered ring can reasonably coordinate the electronic properties. Notably, this work also investigated the mechanism of action of lithium-ion storage and release in detail by means of a particle-swarm intelligence optimization algorithm. Therefore, these interesting findings not only enrich the family of 2-D carbon materials but also provide a new strategy for designing anode materials for lithium-ion batteries.

Biphenylene monolayer: a novel nonbenzenoid carbon allotrope with potential application as an anode material for high-performance sodium-ion batteries.

Allotrope metal structures composed of carbon as anode materials for metal-ion batteries are a current research hotspot. In this work, the recently synthesized graphene allotrope, two-dimensional (2D) biphenylene, consisting of tetragonal, hexagonal and octagonal carbon rings, was explored theoretically. Our first-principles calculations verified that 2D biphenylene has dynamical, mechanical and thermal stability and exhibits metallic features. Its novel structure can provide multiple adsorption sites for Na ions, a fast charge-discharge rate (low Na migration barriers of <0.2 eV) and high theoretical capacity (1075.37 mA h g-1). These superior properties, combined with its carbon abundance and light mass, make the biphenylene monolayer a promising high-performance anode for sodium-ion batteries (SIBs).

Three novel MOFs constructed from 1,3,5-tris(1-imidazolyl)benzene and dicarboxylate ligands with selective adsorption for C2H2/C2H4 and C2H6/CH4.

The urothermal reactions of Co(II)/Zn(II) salts with the diverse carboxylic acid and 1,3,5,-tris(1-imidazolyl)benzene(tib) ligands afforded three novel MOFs, namely, [Co3(tib)2(abdc)2(ox)]2·6H2O (1), [Co3O(tib)(abdc)2(DMI)]·2DMI·2H2O (2) and [Zn3I2(tib)2(napdc)2]·2DMI·2H2O (3), (H2abdc = 5-amino-1,3-benzenedicarboxylate, H2napdc = 1,4-naphthalene dicarboxylic acid and DMI = 1,3-dimethyl-2-imidazolidinone). In compounds 1 and 2, the Co(II) atoms are connected by polycarboxylate ligands to form two-dimensional (2D) layers that are pillared by tib ligands leading to the formation of 3D porous frameworks. In compound 3, the Zn(II) atoms are linked by tib ligands to form one-dimensional ribbon-like chains which are further connected by polycarboxylate ligands, making a 3D framework possible. Compound 1 can selectively adsorb unsaturated hydrocarbon molecules (C2H2 and C2H4) and saturated hydrocarbon molecules (C2H6 and CH4). Specifically, compound 1 has high IAST selectivity for acetylene and methane (0.50 : 0.50, v/v) at 273 K and 1 bar. DFT calculations reveal that the π-conjugated hexagonal carbon ring may be the primary adsorption site because there are π-π interactions between the unsaturated hydrocarbon molecules (C2H2 and C2H4) and the π-conjugated hexagonal carbon ring in the framework of compound 1.

Electrochemical investigation of free-standing reduced graphene oxide hydrogel

Free-standing reduced graphene oxide (RGO) hydrogel was synthesized through two-stepped hydrothermal reduction treatment of aqueous graphene oxide (GO) suspension. GO with high interface affinity for overlapping of cross-linking graphene sheets contributes to forming steady-state RGO hydrogel. RGO hydrogel shows higher B band/G band intensity ratio than GO suspension in Raman spectrum analysis, indicating well-restored hexagonal carbon rings with the enhanced crystal structure. Free-standing RGO hydrogel could be directly acted as supercapacitor electrode without using any substrate material. The specific capacitance decreases from 253.9 to 92.3 F g−1 in 1.0 M Na2SO4 electrolyte and from 275.3 to 125.9 F g−1 in 1.0 M KOH electrolyte when the current density increased from 0.3 to 4.0 A g−1, presenting the capacity retention of 36.4% and 45.7% respectively. Free-standing RGO hydrogel presents specific capacitance in alkaline KOH electrolyte rather than neutral Na2SO4 electrolyte. KOH electrolyte with superior ionic diffusion coefficient of hydroxyl ion leads to higher current response and electrical double-layer capacitance performance. The capacitance retention ratio of 97.8% at 4.0 A g−1 in 1.0 M KOH electrolyte after 1000 charge-discharge cycles presents superior cycling stability. Accordingly, free-standing RGO hydrogel applied well as superior supercapacitor electrode presents the promising energy storage application.

Graphitization of low-density amorphous carbon for electrocatalysis electrodes from ReaxFF reactive dynamics

We predict the three-dimensional structure of amorphous carbon generated by heating diamond superlattice at 6000 K with rapid quenching from the liquid phase for densities ranging from 2.0 to 3.5 g/cm3, in comparison with 2.26 and 3.54 g/cm3 for bulk graphite and bulk diamond, respectively. These predictions are based on reactive dynamics (RD) simulations using the ReaxFF reactive force field. Here, we simulate the graphitization of amorphous carbon at high temperature to calculate physical properties relevant to conductive carbon supports useful for electrocatalysts. The low-density graphitic materials mostly oriented in the (002) plane with a main X-ray diffraction (XRD) peak between 26 and 28°, as observed experimentally. For low density carbon (2.0–2.5 g/cm3), we find >90% sp2 character with ∼2-1% sp and <8% sp3. While for higher density carbon, the amount of sp2 fraction decreases with density and find 70.0% sp3 with 29.7% sp2 and 0.3% sp for 3.4 g/cm3 density, which can be compared to DLC of 3.24 g/cm3 density resulting good agreement with XPS experiments. Based on the simulated 3D structure, we create 2D surface slab consisting of various defective sites within the surface. The 2D surface dominates with hexagonal carbon ring along with few pentagon and heptagon rings in the graphitic structure that may be useful as electrocatalysts for different energy conversion reactions.

Theoretical characterization and application of mechanical behavior of atoms/ions migrating on graphene surface

The static and dynamic mechanical behaviors of atoms/ions migrating on graphene surface are investigated via theoretical and numerical calculations, and a design idea of nano-scale device that can be used for atoms/ions screening is proposed on this basis. By using the Fourier expansion of the interaction potential between atoms, the analytical expression of the interaction force between an atom/ion and infinitely large graphene is derived. The dependence of the interaction force on the vertical distance from the atom/ion to graphene surface and the atomic/ionic types are analyzed. Based on the interaction force, a dynamics governing equation for the migration of atoms/ions on graphene surface is established, and the dynamics behaviors of atoms/ions when they migrate on the graphene surface at different initial velocities are studied. Taking lithium-ion as an example, it is found that there are three migration states along the armchair direction of graphene. No matter which migration state, the lithium-ion will eventually be stably adsorbed above the center of a hexagonal carbon ring (the hollow site). By adjusting the initial velocity, the lithium-ion can be steadily adsorbed at the specified sites, so as to control the migration distance of lithium-ion. What's more, the functional relationship between the critical initial velocity of the lithium-ion and the stable adsorption sites on graphene surface is given, and the influence of the vertical distance from the lithium-ion to graphene surface on the migration process is analyzed. In addition, the dynamics behaviors of the migration of different atoms/ions on graphene surface are studied, and it is found that the migration of alkali metal particles is more free with the increase of atomic number, and the stable site is further away from the initial position, which is in good agreement with the results of molecular dynamics simulation in the literature. Besides, the effects of initial position, damping and migration path on the dynamics behaviors of atoms/ions migrating on graphene surface are also studied. Finally, on the basis of theoretical results, a design idea of graphene-based nano-scale device is proposed, which can be used to screen specified atoms/ions and control their in and out positions.

A Cyclized Polyacrylonitrile Anode for Alkali Metal Ion Batteries

AbstractOrganic anodes have attracted increasing attention for alkali metal ion batteries. In this work, we discovered that cyclized polyacrylonitrile (cPAN) can serve as an excellent anode for alkali metal ion batteries. Upon activation cycling, as an anode of lithium‐ion battery, cPAN exhibits a reversible capacity as high as 1238 mAh g−1under a current density of 50 mA g−1. Based on electrochemical experiments and first‐principles calculations, it is demonstrated that the hexagonal carbon ring, piperidine ring, and pyridine nitrogen in ladder cPAN are the main active sites for lithium‐ion storage. cPAN displays a unique potential‐dependent solid electrolyte interphase formation from 0.1 to 0.01 V vs. Li/Li+. It also displays decent performance as an anode in SIBs and PIBs.