Superior mechanical flexibility, lattice thermal conductivity and electron mobility of the hexagonal honeycomb carbon nitride monolayer

Zhang, Tian; Lin, Jiahe; Jia, X.

doi:10.1039/d2cp01104b

Cited by 5 publications

(3 citation statements)

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“…We have kept the variation in strain in the range of ±0.05%. 59 Essentially, the longitudinal acoustic (LA) phonon modes contribute to volume deformations at first order with accountable scattering rates, whereas the shear components are usually less important. Therefore, we can neglect the effect of the shear strain and treat LA phonons responsible for changes in the volume of the crystal, which gives rise to a perturbing potential, shifting the electronic band energy.…”

Section: Methodsmentioning

confidence: 99%

“…This can be estimated using this simplified relation E normalD normalP = normalΔ E normale normald normalg normale normalΔ a a where Δ E edge is the energy shift in the band edge due to uniaxial strain, and Δ a is the change in the lattice constant. We have kept the variation in strain in the range of ±0.05% . Essentially, the longitudinal acoustic (LA) phonon modes contribute to volume deformations at first order with accountable scattering rates, whereas the shear components are usually less important.…”

Section: Methodsmentioning

confidence: 99%

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Spontaneous Dumbbell Formations via Surface Functionalization of the C₃N Monolayer with Versatile Electronic and Mechanical Properties

Jana,

Mondal,

Roy

et al. 2023

J. Phys. Chem. C

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This article theoretically explores the formation of dumbbell (DB)-like structures by elemental adsorption on the recently synthesized C3N monolayer. Owing to the repulsion from N atoms, different elements from groups III, IV, and V (B, C, Si, Ge, P, and As) have been examined to form DB-like cages when adsorbed on the opposite sides of the substrate. After establishing the dynamical and thermodynamic stability of these materials, their mechanical durability is analyzed. DBs formed by adatoms like P and As provide the highest in-plane stiffness while that by B exhibits the highest Poisson ratio. The ultimate tensile strain turns out to be quite high (around 18%) for the DB C3NP and C3NAs. Electronic band structure depicts semimetallic and semiconducting characteristics depending on the type of adsorbate that can be further tuned via external strain. Both DB C3NP and C3NAs undergo an indirect-to-direct band gap transition, while the semimetals show band gap opening of the order of meV under applied tension. The presence of space–time inversion symmetry with a well-known effective low-energy tight-binding Hamiltonian easily captures the event of linear band crossings in these materials. The valence orbital theory also nicely explains the origin of Dirac cones as well as the semiconducting indirect band gaps. There is visible anisotropy in the Fermi velocity, which can embrace high values such as 7.5 × 105 ms–1 at a specific direction, and this inhomogeneity measure is remarkably high (around 90%) for the Dirac materials. Electronic transport properties such as carrier-dependent effective mass and mobility also possess anisotropies by their very exotic nature. The findings here highlight a distinct class of 2D carbon nitrides with anisotropic Dirac semimetals and indirect gap semiconductors with plausible synthesis routes, which show great potential in nanodevice applications.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Spontaneous Dumbbell Formations via Surface Functionalization of the C₃N Monolayer with Versatile Electronic and Mechanical Properties

Jana,

Mondal,

Roy

et al. 2023

J. Phys. Chem. C

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“…6 Though CN x is one of the leading materials for particulate photocatalytic solar energy conversion so far, the performance of systems coupled with water oxidation is still too low for widespread use. Limitations of pristine CN x include limited light absorption of the solar spectrum, faster charge recombination compared to the kinetically competing redox reactions, and low charge carrier mobility (μ h = 1.7 × 10 −4 cm 2 V −1 s −1 from field effect measurements) 7,8 compared to 2D organic materials, for instance, boron carbon nitride (μ h /μ e = 5−20 cm 2 V −1 s −1 ) 9,10 and a CN x monolayer (μ e = 1617.52 cm 2 V −1 s −1 ), 11 and other organic conjugated polymers, such as the common material poly-3-hexylthiophene (P3HT) (μ h = 10 −4 −10 −3 cm 2 V −1 s −1 ). 12 The photocatalytic solar fuel production process can be separated into four steps: light absorption by the light absorber, charge generation of electron−hole pairs, charge transport to the surface of the semiconductor, and interfacial charge transfer for surface redox reactions.…”

Section: ■ Introductionmentioning

confidence: 99%

ALD-Deposited NiO Approaches the Performance of Platinum as a Hydrogen Evolution Cocatalyst on Carbon Nitride

Liu

Godin

2022

ACS Catal.

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The photocatalytic hydrogen evolution reaction is one of the most promising approaches to utilize solar energy and produce hydrogen as an alternative energy source to traditional fossil fuels. In this work, we focused on further exploring the cocatalyst potential of the transition metal nickel and prepared nickel oxide/ carbon nitride (NiO/CN x ) heterojunctions through thermal polymerization as well as plasma-enhanced atomic layer deposition (PEALD). The optimal NiO loading thickness on the surface of the CN x was found to be 6.5 nm, prepared from 65 cycles of ALD. This NiO(65)/CN x had a photocatalytic hydrogen evolution rate of 3.9 μmol h −1 in a 2 mg mL −1 aqueous photocatalyst solution (195 μmol h −1 g −1 ), corresponding to an AQY of 3.1% and exhibiting 54% of the activity of 3 wt % Pt/CN x under 405 nm light illumination with a sacrificial reagent. A 3 wt % Ni/CN x prepared through a photodeposition process from a dispersion of CN x and simple NiCl 2 had a photocatalytic hydrogen evolution rate of 2.8 μmol h −1 (140 μmol h g −1 ) and an AQY of 2.2% with 2 mg mL −1 photocatalyst in the reactant solution, corresponding to 39% of the activity of 3 wt % Pt/CN x . An induction period at the beginning of the hydrogen evolution process was found in all Ni-based photocatalysts, which we related to a Ni in situ photoreduction from Ni II to Ni 0 and the reverse reaction. In addition, the reproducibility of the induction period even in an oxygen-free environment suggests that electrons flow back from reduced Ni species to CN x under dark conditions. Furthermore, a large population of trap states was detected in the bulk CN x materials via photoinduced absorption spectroscopy, and the trapping severely hinders cocatalysts (even the benchmark Pt cocatalyst) from extracting charges from CN x for subsequent interfacial redox reactions. We conclude that not only does the surface/interface engineering of the photocatalyst/ catalyst heterojunctions need to be considered but also trap states in CN x that severely limit the transfer of photogenerated charges to cocatalysts.

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Rectangular Carbon Nitrides C₄N Monolayers with a Zigzag Buckled Structure: Quasi‐1D Dirac Nodal Lines and Weak Topological Properties with Flat Edge States

Li,

Song

et al. 2024

Adv Funct Materials

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Using first‐principles calculations, two C4N monolayers with a zigzag buckled (ZB) structure are proposed. The ZB C4N monolayers contain raised‐C (raised‐N) atoms with sp3 hybridization, different from the traditional 2D graphene‐like carbon nitride materials with sp2 hybridization. Interestingly, the band structures of the ZB C4N monolayers exhibit quasi‐1D Dirac nodal line resulting from the corresponding quasi‐1D structure of the zigzag carbon chains, which is essentially different from the conventional ring‐shaped nodal line. The quasi‐1D Dirac nodal line exhibits the following features: i) gapless Dirac points, ii) varying Fermi velocity, and iii) a slightly curved band along the high‐symmetry path. All these features are successfully explained by the proposed tight‐binding model that includes interactions up to the third nearest neighbor. The Fermi velocity of the 2D system can reach 105 m s−1, which is promising for applications in high‐speed electronic devices. The topological flat band structure of the corresponding 1D system determined by the Zak phase and band inversion is edge‐dependent, which is a weak topological state and can be explained by the 2D Su‐Schrieffer‐Heeger (SSH) model. The quasi‐1D Dirac Fermions and SSH edge states make the ZB C4N monolayers promising for nanoelectronics applications.

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Superior mechanical flexibility, lattice thermal conductivity and electron mobility of the hexagonal honeycomb carbon nitride monolayer

Abstract: Nitrogen is the nearest neighbor element of carbon, and thus the hexagonal honeycomb carbon nitride monolayer (CxNy) consisted of a covalent network of carbon and nitrogen atoms can usually own...

Cited by 5 publications

References 60 publications

Spontaneous Dumbbell Formations via Surface Functionalization of the C₃N Monolayer with Versatile Electronic and Mechanical Properties

Spontaneous Dumbbell Formations via Surface Functionalization of the C₃N Monolayer with Versatile Electronic and Mechanical Properties

ALD-Deposited NiO Approaches the Performance of Platinum as a Hydrogen Evolution Cocatalyst on Carbon Nitride

Rectangular Carbon Nitrides C₄N Monolayers with a Zigzag Buckled Structure: Quasi‐1D Dirac Nodal Lines and Weak Topological Properties with Flat Edge States

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Superior mechanical flexibility, lattice thermal conductivity and electron mobility of the hexagonal honeycomb carbon nitride monolayer

Abstract: Nitrogen is the nearest neighbor element of carbon, and thus the hexagonal honeycomb carbon nitride monolayer (CxNy) consisted of a covalent network of carbon and nitrogen atoms can usually own...

Cited by 5 publications

References 60 publications

Spontaneous Dumbbell Formations via Surface Functionalization of the C3N Monolayer with Versatile Electronic and Mechanical Properties

Spontaneous Dumbbell Formations via Surface Functionalization of the C3N Monolayer with Versatile Electronic and Mechanical Properties

ALD-Deposited NiO Approaches the Performance of Platinum as a Hydrogen Evolution Cocatalyst on Carbon Nitride

Rectangular Carbon Nitrides C4N Monolayers with a Zigzag Buckled Structure: Quasi‐1D Dirac Nodal Lines and Weak Topological Properties with Flat Edge States

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Product

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About

Spontaneous Dumbbell Formations via Surface Functionalization of the C₃N Monolayer with Versatile Electronic and Mechanical Properties

Spontaneous Dumbbell Formations via Surface Functionalization of the C₃N Monolayer with Versatile Electronic and Mechanical Properties

Rectangular Carbon Nitrides C₄N Monolayers with a Zigzag Buckled Structure: Quasi‐1D Dirac Nodal Lines and Weak Topological Properties with Flat Edge States