Electronic structures of diamane doped with metal atoms†

Shiyang Fu, Qiyuan Yu, Junsong Liu, Nan Gao* and Hongdong Li*
State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China. E-mail: gaon@jlu.edu.cn; hdli@jlu.edu.cn

First published on 16th August 2024

---

---

1. Introduction

Since its successful synthesis, graphene has been eagerly explored for its structures, properties and applications.^1–3 Due to the limitation of the zero-gap, the hydrogenated and fluorinated graphenes (graphane and fluorographene) have large bandgaps,^2,4 which is quite exceptional for their electronic applications. Recently, diamane (single-layer diamond) has emerged as a novel two-dimensional material.^5–7 Different from graphene, surface functionalization (such as hydrogenation, fluorination,^8,9 and oxidation¹⁰), substitution, or reconstruction¹¹ of diamane are necessary for its structural stability.^12,13 Diamane maintains a diamond-like structure with excellent mechanical flexibility and resistance to deformation, and shows high elastic constants (C₁₁ of 526.28–798.09 N m⁻¹)^14–16 and Young's modulus (485–519.86 N m^−114,17 and 795 GPa).¹⁶ Also, its elastic properties significantly exceed those of many two-dimensional materials, such as MoS₂ (C₁₁ of 140 N m⁻¹),¹⁸ phosphorene (Young's modulus of 92.39 N m⁻¹)¹⁹ and arsenene (Young's modulus of 31.3895 GPa).²⁰ Its two-dimensional size facilitates remarkable thermoelectric and piezoelectric properties.¹⁵ Predicted by density functional theory (DFT) calculations, fluorinated diamane (F-diamane) has a direct band gap of 3.86 eV, as well as a controllable bandgap and extraordinary carrier mobility,^9,21 and is potentially applied in nano-optics, nanoelectronics, and nano-electromechanical systems. By constructing Janus and non-Janus structures, diamane shows a high negative Poisson's ratio, which is an indicator of excellent energy dissipation capabilities.²²

Especially, by exposing bilayer graphene to hydrogen radicals or XeF₂, hydrogenated diamane (H-diamane) and F-diamane have been successfully synthesized experimentally.^23,24 The application of a graphene/diamane interface in a solar cell has been reported, and an efficiency of 31.2% is achieved.¹⁷ It is found that Cu- and Fe-doped diamanes are preferred for applying in electroreduction of CO₂, and Ni-doped diamane is favorable for the hydrogen evolution reaction, due to the significantly enhanced CO₂ adsorption ability facilitated by dopants.²⁵ The results are different from those of transition metal dichalcogenides, which show enhanced adsorption interaction and selectivity for gas detection,²⁶ while they are quite inert toward CO₂. The difference in CO₂ catalytic characteristics presents a potential advantage for diamane in the field of catalysis. Consequently, further investigation into its synthesis conditions and utilization in nano-electronic devices is highly promising.

Surface doping and atomic substitution enable the attainment of remarkable electronic properties, thereby presenting significant prospects for practical applications.²⁷ In addition, defects and substitutional doping can induce the magnetic state,^28,29 for example, graphane,^30,31 arsenene³² and h-BN³³ present magnetism upon doping or embedding metal atoms, and their electronic properties are changed. Diamane is a non-magnetic semiconductor, by substitutional doping with metal atoms, we suppose that diamane could show magnetism and unexpected electronic properties. On the other hand, due to the intricate synthesis conditions required for diamane, practical applications of diamane are impeded. It has been reported that B doping can lower the energy barrier for conversion of bilayer graphene to H-diamane^34,35 and F-diamane.¹⁴ Additionally, it is reported that introducing transition metal atoms can promote the transformation of graphene into a bulk diamond phase.^36,37 The influence of metal atom doping on diamane synthesis remains an open question. This motivates us to investigate the unrevealed magnetic and electronic properties of diamane by substitutional doping.

In this work, we used 19 kinds of metal atoms (Li, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, Ag, Pt and Au) to investigate their effect on the conversion of bilayer graphene to a diamane structure, then the magnetic and electronic properties of metal-atom-doped/embedded diamane are studied based on the first-principles calculations.

2. Computational details

The calculations were carried out using DFT as implemented in the Vienna Ab-initio Simulation Package (VASP).^38,39 The generalized gradient approximation (GGA) of the Perdew–Burke–Ernzerhof (PBE) functional was used for the exchange–correlation functional.⁴⁰ As shown in Table S1 (ESI†), we chose three functionals (PBE, LDA, and HSE06) to calculate the interlayer separation of F-diamane (2.054, 2.024, and 2.054 Å), which were similar to other results (2.06,⁴¹ 2.05⁴² and 2.056 Ź⁴) and experimental data (2.05 Ų³). This indicates that the PBE functional was reliable for structural optimization. After comparison with experimental results (Table S1, ESI†), the DFT-D3 correction was adopted to account for the van der Waals interaction.⁴³ This correction method is applicable to all elements of the periodic table, to molecules and solids, within about 10% accuracy can be achieved, and it is robust, numerically stable, easily programmable, very fast, and allows for the straightforward computation of analytical gradient forces.⁴⁴ In addition, the DFT-D3 method has been used for correcting the adsorption system's interaction for transition metal doped graphene,⁴⁵ arsenene⁴⁶ and transition-metal dichalcogenides.⁴⁷ The projector-augmented wave (PAW) method was adopted to describe the interactions between the core electrons and valence electrons. The convergence criteria were set to be 10⁻⁵ eV Å⁻¹ for the energy and 0.03 eV Å⁻¹ for the maximal residual force. According to the convergence test results shown in Fig. S1 (ESI†), a plane wave cutoff energy of 520 eV and the Monkhorst–Pack k-point sampling with a 4 × 4 × 1 mesh were utilized during structural relaxation and electronic property calculations. All calculations were performed with spin polarization. To avoid the artificial interaction between periodic images, a vacuum layer of 25 Å was added.

The energy barriers for the transformation of bilayer graphene into a diamane structure doped with a metal atom were calculated by using the climbing-image nudged elastic band (CI-NEB) method, in which variable spring constants were used to increase the density of images near the top of the energy barrier for improved estimation of the reaction coordinate near the saddle point.⁴⁸ The geometry and energy of the transformations of the four intermediate images were optimized until the total energy became less than 10⁻⁴ eV. In order to reduce the interactions between metal atoms in adjacent supercells, a 4 × 4 supercell was used to study the structural and electronic properties, and a 2 × 2 supercell was used for the transition state calculations.

The formation energy (E_F) of diamane from the graphene bilayer is defined as

	(1)

where E_total is the energy of pristine or doped diamane, and E_gra represents the energy of bilayer graphene with or without vacancy defects, E_H2 is the energy of H₂ molecules, E_metal is the energy of a single metal atom. m and n correspond to the numbers of H atoms and total atoms in structures.

The binding energy (E_b) of metal atoms to a substrate is defined as

Eb = Etotal − Emetal − Esubstrate	(2)

where E_substrate is total energy of the substrate (H-diamane or F-diamane). Based on this definition, the larger the values of binding energies, the stronger is the chemical bonding with the interface.

The cohesive energy (E_coh) of bulk metals is defined as

	(3)

where E_bulk is the energy of a bulk structure.

3. Results and discussion

3.1 Phase-transition barrier and process

Fig. 1 shows the process of bilayer graphene transforming into a diamane structure. To simplify this process, we intentionally design the initial structure to ensure that the C atom and H atom on the other side do not directly participate in the reaction. It is because that this study focuses on the effect of transition metals on the energy barriers during the reaction. In addition, the synthesis of diamond and diamane is usually conducted in the H plasma²⁴ or XeF₂ vapour,²³ which is easy for the formation of C–H or C–F bonds. A similar treatment has been used for the formation of bulk diamond.³⁶

To investigate the impact of metal atoms on diamane formation, we introduce Ti, Co, Ni and Pt atoms for example attached to one side of bilayer graphene and cover the other side with H atoms. Simultaneously, we simulate the pristine H-diamane for comparison. When the two graphene layers approach each other, the sp² C atoms change to the sp³ C atoms, and the interface C–C bonds form (Fig. 1a). As presented in Fig. 1b, the energy barrier of the system without a metal atom is about 0.0146 eV Å⁻², suggesting that it is thermodynamically difficult to directly convert bilayer graphene into a diamane structure if no energy is applied. This conclusion is consistent with the experimental results that bilayer graphene diamondization could be realized by applying pressure and using adsorption chemistry of H or F plasma.^6,23,24 When a metal atom (Ti, Co, Ni and Pt atoms here) is introduced, the energy barrier values reduce to 0.0064, 0.0008, 0.0074 and 0.0009 eV Å⁻² during diamane formation, suggesting its facilitative role in converting bilayer graphene into diamane. Although the metal atom does not directly participate in the bond formation, it can still influence the reaction. The d orbitals of transition metals can interact with the molecular orbitals of carbon atoms, altering the electronic structure and energy of the reactants. This interaction can facilitate charge transfer and accumulation, as evidenced by previous reports on the use of transition metals to reduce the reaction barrier between graphite and diamond.³⁶ In addition, the energy difference between the initial and final structures is smaller, when a metal atom is present. It is because that the bond strength between M and C atoms in doped diamane is weaker than the C–H bond energy in diamane.

3.2 H-diamane and F-diamane doped with a metal atom

In the following, we systemically investigate the structural and electronic properties of diamane doped with a metal. Both H-diamane and F-diamane are considered, and 19 kinds of metal atoms (Li, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, Ag, Pt and Au) are selected. The lattice constants for pristine H-diamane and F-diamane are 2.529 Å and 2.561 Å, which are similar to the previous theoretical results (2.51–2.53 Å for H-diamane and 2.54–2.56 Å for F-diamane).^22,41,49 First, a supercell with chemical formulae of C₆₄H₃₂ and C₆₄F₃₂ are built, and a H or F atom is replaced by a metal atom to construct a doped structure, which is named M–C₆₄H₃₁ or M–C₆₄F₃₁.

Fig. 2a shows a schematic diagram of a doped diamane structure. It is found that the substrate structure remains almost unaltered, and the metal atom moves out of the plane due to its large atom sizes. The distances between the metal atom and the nearest C atoms are 1.95–2.76 Å and 1.93–2.80 Å for M–C₆₄H₃₁ or M–C₆₄F₃₁, respectively (Table S2, ESI†). To study the structural stability, we calculate the binding energy and compare it with the cohesive energy of bulk metals in Fig. 2b, and the data are listed in Table S2 (ESI†). For H-diamane doped with metals, only E_b of K–C₆₄H₃₁ is more negative than E_coh, other metal atoms have larger E_coh than E_b. It suggests that K–C₆₄H₃₁ is stable, while the other metals would agglomerate on H-diamane. Especially, for F-diamane, E_b values of Li, Na, K, Al, Mg, Ca atom adsorbed structures are more negative than their E_coh, thus they can be stably and uniformly doped on the surface. For stable doped structures, M–C bond lengths of K–C₆₄H₃₁, K–C₆₄F₃₁ and Ca–C₆₄F₃₁ are smaller than the sum of covalent radii, while others have slightly larger M–C bond lengths compared with the sum of covalent radii. Thus, the substantial adsorption energies in Table S2 (ESI†) suggest that the interaction between the metal atoms and diamane is primarily chemisorption. It has been reported that F-diamane doped with Li (Li–C₆₄F₃₁) shows effectively increased adsorption capability, sensitivity energy and transferred charge between the substrate and volatile organic compounds, thus it is a promising sensing material.⁴²

In the process of graphene transforming into diamane, the metal atoms involved in the reaction may also lead to substitution doping of C atoms. In addition, due to the less stable structures of M–C₆₃H₃₁ and M–C₆₃F₃₁, we built the metal-atom-embedded diamane structures, where a metal atom replaces the C and H (F) atoms, and the structures are defined as M–C₆₃H₃₁ or M–C₆₃F₃₁. As shown in Fig. 3, due to the larger room of C and H (F) atoms, metal atoms are embedded in diamane. The bond distances between the metal atoms and the nearest C atoms are 1.82–2.75 Å and 1.86–3.52 Å for M–C₆₃H₃₁ and M–C₆₃F₃₁ (Table S3, ESI†). The K–C bond length is the largest, and the Co–C bond length is the shortest, because of their different atomic radii and electron affinities. As shown in Fig. 3b, only Co–C₆₃H₃₁ is the stable structure for H-diamane. For F-diamane, Li, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co and Ni structures are stable. Among the stable doped structures, the bond lengths of M–C for Co–C₆₃H₃₁, Al–C₆₃F₃₁, Fe–C₆₃F₃₁, Co–C₆₃F₃₁ and Ni–C₆₃F₃₁ are smaller than their summation of covalent bonds, indicating the covalent feature. Thus, the interaction of metals and C atoms is a weak polar covalent bond. As expected, more metals are stably doped into F-diamane. Since the F atom has a significantly higher electronegativity (3.98) than H (2.20), the polarity enhances the stability of the C–F bond, making it less susceptible to interaction with metal atoms. Conversely, the similar electronegativities between H and metal atoms can destabilize the C–H bond upon metal doping. A similar phenomenon has been observed in F and H terminated diamonds.⁵⁰

In addition, to further investigate the influence of metal atoms on diamane formation from the graphene bilayer, we calculate the formation energy of H/F-diamane with metal atoms (Fig. S2, ESI†). The formation energy of H-diamane doped with metals (Al, Ti, Fe, Co, Ni, Cu, Pd, Pt and Au) is lower than that of pure H-diamane. This suggests that these transition metals positively influence the synthesis of H-diamane. It is consistent with the transition state results in Fig. 1, where the addition of transition metals reduces the formation of the energy barrier. However, in the case of F-diamane with metal atom absorption (M–C₆₄F₃₁), doping with metal atoms does not lead to a reduction in formation energy. For diamane embedded with metals, the formation energy decreases for Ti–C₆₃H₃₁, Co–C₆₃H₃₁, Ni–C₆₃H₃₁, Pt–C₆₃H₃₁, Ti–C₆₃F₃₁, V–C₆₃F₃₁, and Co–C₆₃F₃₁. The results indicate that the existence of these metals is beneficial for the formation of H-diamane or F-diamane, while other metals should be avoided in the formation process.

3.3 Electronic properties of H-diamane and F-diamane doped with a metal atom

The spin-polarized band structures of metal-atom-absorbed diamane are displayed in Fig. 4, and we only investigate the electronic properties of stable structures. It can be observed that the adsorption of metal atoms leads to the emergence of flat bands lower than the Fermi level, resulting in a reduced band gap. The flat bands near Fermi level are mainly contributed by diamane, with a slight contribution of doped atoms (Fig. S3, ESI†). While the situation is different in Mg–C₆₄F₃₁ and Al–C₆₄F₃₁, the flat bands near the Fermi level are both contributed by doped atoms and diamane. In addition, there is evident orbital overlap between the p-orbital of the substrate and the s/p-orbital of metal atoms near the Fermi level, indicating a strong interaction. For Mg–C₆₄F₃₁ and Ca–C₆₄F₃₁ systems, spin splitting appears in band structures, indicating that magnetism exists in the structures. Especially, the Ca–C₆₄F₃₁ system exhibits half-metallic feature. s electrons for Li, Na, and K and 3p electrons for the Al atom could be paired with the dangling bond of the C atom, making non-magnetic structures. While for the case of Mg–C₆₄F₃₁ and Ca–C₆₄F₃₁, there are two s electrons in Mg and Ca atoms, the unpaired electron induces the polarization of electrons. For Mg–C₆₄F₃₁ and Al–C₆₄F₃₁, the orbital contribution of the metal atom to the impurity level is different from that of others, which is due to the difference in the valence electron configuration after exchanging electrons with the substrate.

In Fig. 5, the spin-resolved band structures of metal-atom-embedded diamane are presented. It can be found that spin splitting occurs in all structures except the Co–C₆₃H₃₁, Al–C₆₃F₃₁ and Co–C₆₃F₃₁ structures. The unsaturated electrons of metal atoms result in the polarization of electrons and thus the magnetic moment. For example, in Ti–C₆₃F₃₁, three electrons of Ti bond with neighboring three C atoms, leaving one unpaired electron. However, the situation of Co is different, three electrons of Co participate in the formation of Co–C bonding and two nonbonding orbitals are filled with four electrons, thus the structure is nonmagnetic. A similar situation is observed for Al-doped diamane, where the Al atom possesses three electrons. The magnetic properties have been reported for transition metal atom-doped graphane.³⁰ The Mg–C₆₃F₃₁, Ca–C₆₃F₃₁, V–C₆₃F₃₁, Mn–C₆₃F₃₁ and Ni–C₆₃F₃₁ systems exhibit half-metallic properties, and other structures have semiconductor properties with reduced bandgaps. In Fig. S4 (ESI†), we observe a significant difference of orbitals between the transition metal atoms and the alkali metal atoms. For Li–C₆₃F₃₁, Na–C₆₃F₃₁ and K–C₆₃F₃₁, the split state near the Fermi level is nearly all contributed by 2p orbitals of C atoms in F-diamane. For Mg–C₆₄F₃₁ and Al–C₆₄F₃₁, the flat bands near the Fermi level are both contributed by doped atoms and diamane. For C₆₃F₃₁ doped with a transition metal, the splitting of electron states near the Fermi level is mainly provided by the 3d orbitals of transition metal atoms.

Since the PBE functional generally underestimates the band gap, we calculate the band gap of F-diamane using the more-accurate HSE06 functional in Fig. S5a (ESI†), the tendency is similar except an enlarged bandgap. In addition, the doped structure of Li–C₆₃F₃₁ is chosen as an example, due to its nonmagnetic feature. The band structure is calculated using the HSE06 functional (Fig. S5b, ESI†), and the bands near the Fermi level are similar to those calculated using the PBE functional, except that the band gap values differ by about 1 eV. The credible surface properties of transition metal doped MoTe₂,⁵¹ MoSe₂⁵² and MoS₂⁵³ have been obtained using the PBE method. Considering the limited computational resources, the PBE method is used to calculate the electronic properties in this work.

In order to further investigate the electronic properties of the doped structure, we perform charge density difference calculations, and the results are shown in Fig. 6. For all doped structures, the evident charge distribution in the interface indicates that there is electron exchange between the metal atoms and the substrate, which is also confirmed by the Bader charge results in Fig. S6 (ESI†). In K–C₆₄H₃₁ and K–C₆₄F₃₁ structures, charge accumulation only occurs between the K atom and diamane, while no bonding is observed between K and the bottom C atom. Conversely, for other doped structures, metal atoms exhibit both charge exchange and bonding with the bottom C atom, resulting in enhanced structural stability. Notably, diamane doped with transition metals exhibits a higher degree of accumulated charges than that of diamane doped with alkali metal atoms, suggesting that transition metals form more stable bonds with the substrate and thus forming a lower energy barrier.

Finally, we suppose that transition metal-doped diamanes have a wide range of practical applications, which can be used in electronic devices as electrodes, conductors, and semiconducting materials, due to their electrical properties and magnetism.¹⁷ Moreover, transition metals provide active sites on the diamane surface, which can serve as efficient catalysts for various chemical reactions to facilitate water splitting, oxygen reduction, and organic synthesis. For example, electroreduction of CO₂ on Cu, Fe, or Ni-doped diamane sheets has been proposed.²⁵ Additionally, their high surface area and sensitivity could also make them ideal for the development of high-performance sensors for gas detection, biosensing, and environmental monitoring.⁴²

4. Conclusion

In summary, we systematically calculate the structural and electronic properties of H-diamane and F-diamane doped with 19 metal atoms (Li, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, Ag, Pt and Au) using first principles calculations. First, we investigate the influence of Ti, Co, Ni and Pt atoms for example on the transformation process of bilayer graphene into H-diamane and find that the reaction energy barrier is effectively lower, indicating that the metal atom doping is beneficial for the transition from graphene bilayer to diamane. Furthermore, for H-diamane structures, K–C₆₄H₃₁ and Co–C₆₃H₃₁ are determined to be theoretically stable. Regarding F-diamane structures, more stable structures are stable (Li–C₆₄F₃₁, Na–C₆₄F₃₁, Mg–C₆₄F₃₁, Al–C₆₄F₃₁, K–C₆₄F₃₁, Ca–C₆₄F₃₁, Li–C₆₃F₃₁, Na–C₆₃F₃₁, Mg–C₆₃F₃₁, Al–C₆₃F₃₁, K–C₆₃F₃₁, Ca–C₆₃F₃₁, Ti–C₆₃F₃₁, V–C₆₃F₃₁, Cr–C₆₃F₃₁, Mn–C₆₃F₃₁, Fe–C₆₃F₃₁, Co–C₆₃F₃₁ and Ni–C₆₃F₃₁). The band structure analysis reveals that all structures exhibit reduced band gaps due to the introduction of dopants. Specially, Ca–C₆₄F₃₁, Mg–C₆₃F₃₁, Ca–C₆₃F₃₁, V–C₆₃F₃₁, Mn–C₆₃F₃₁ and Ni–C₆₃F₃₁ systems transform into the semi-metal state, due to the interaction between the outer orbitals of metal atoms and the p orbitals of C atoms in diamane, resulting in new bonding orbitals near the Fermi level. The differential charge density indicates distinct electron exchange between the metals and the substrate. This research provides novel insights into diamane synthesis as well as bridges the gaps in the understanding of the alteration of the properties of diamanes by metal atoms.

Data availability

The data supporting this article have been included as part of the ESI.†

Conflicts of interest

There are no conflicts to declare.

Acknowledgements

This work was supported by the Program of Science and Technology Development Plan of Jilin Province of China (No. SKL202302006) and the National Natural Science Foundation of China (NSFC) (No. 52172044, 51972135). Computation was carried out at the High-Performance Computing Center of Jilin University. The authors acknowledge the Instrument and Equipment Sharing Platform of State Key Laboratory of Superhard Materials, Jilin University.

References

1. Y. Zhang, Y.-W. Tan, H. L. Stormer and P. Kim, Experimental observation of the quantum Hall effect and Berry's phase in graphene, Nature, 2005, 438(7065), 204 Search PubMed .
2. A. K. Geim, Graphene:StatusandProspects, Science, 2009, 324, 1530 CrossRef CAS PubMed .
3. J. Wang, X. Jin, C. Li, W. Wang, H. Wu and S. Guo, Graphene and graphene derivatives toughening polymers: Toward high toughness and strength, Chem. Eng. J., 2019, 370, 831–854 CrossRef CAS .
4. O. Leenaerts, H. Peelaers, A. D. Hernández-Nieves, B. Partoens and F. M. Peeters, First-principles investigation of graphene fluoride and graphane, Phys. Rev. B: Condens. Matter Mater. Phys., 2010, 82(19), 195436 CrossRef .
5. G. Qin, L. Wu and H. Gou, Diamane: design, synthesis, properties, and challenges, Funct. Diam., 2021, 1(1), 83–92 CrossRef .
6. P. B. Sorokin and B. I. Yakobson, Two-Dimensional Diamond-Diamane: Current State and Further Prospects, Nano Lett., 2021, 21(13), 5475–5484 CrossRef CAS .
7. F. Lavini, M. Rejhon and E. Riedo, Two-dimensional diamonds from sp2-to-sp3 phase transitions, Nat. Rev. Mater., 2022, 7, 814–832 CrossRef .
8. K. D. Pham, Tunable structural and electronic properties of C4XY (X ≠ Y = H, Cl and F) monolayers by functionalization, electric field and strain engineering, New J. Chem., 2022, 46(19), 9383–9388 RSC .
9. T. V. Vu, H. V. Phuc, S. Ahmad, V. Q. Nha, C. Van Lanh, D. P. Rai, A. I. Kartamyshev, K. D. Pham, L. C. Nhan and N. N. Hieu, Outstanding elastic, electronic, transport and optical properties of a novel layered material C(4)F(2): first-principles study, RSC Adv., 2021, 11(38), 23280–23287 RSC .
10. L. A. Varlamova, S. V. Erohin, K. V. Larionov and P. B. Sorokin, Diamane Oxide. Two-Dimensional Film with Mixed Coverage and a Variety of Electronic Properties, J. Phys. Chem. Lett., 2022, 13(49), 11383–11390 CrossRef CAS PubMed .
11. T. Pakornchote, A. Ektarawong, W. Busayaporn, U. Pinsook and T. Bovornratanaraks, Roles of nitrogen substitution and surface reconstruction in stabilizing nonpassivated single-layer diamond, Phys. Rev. B, 2020, 102(7), 075418 CrossRef CAS .
12. L.-s Li and X. Zhao, Transformation between Different Hybridized Bonding Structures in Two-Dimensional Diamond-Based Materials, J. Phys. Chem. C, 2011, 115(45), 22168–22179 CrossRef CAS .
13. H. Li, J. Li, Z. Wang and G. Zou, Layer number-dependent structural evolution of two-dimensional diamond films, Chem. Phys. Lett., 2012, 550, 130–133 CrossRef CAS .
14. L. Gao, Y. Liu, Y. Liang, N. Gao, J. Liu and H. Li, Structural stability and electronic and mechanical properties of nitrogen- and boron-doped fluorinated diamane, Phys. Chem. Chem. Phys., 2023, 25(36), 24518–24525 RSC .
15. L. A. Chernozatonskii, P. B. Sorokin, A. G. Kvashnin and D. G. Kvashnin, Diamond-like C2H nanolayer, diamane: Simulation of the structure and properties, JETP Lett., 2009, 90(2), 134–138 CrossRef CAS .
16. P. Polyakova, L. Galiakhmetova, R. Murzaev, D. Lisovenko and J. Baimova, Elastic properties of diamane, Lett. Mater., 2023, 13(2), 171–176 CrossRef .
17. P. K. Naima, P. K. Tyagi and V. Singh, Potential application of novel graphene/diamane interface in silicon-based heterojunction with intrinsic thin layer solar cell, Comput. Mater. Sci., 2023, 226, 112252 CrossRef CAS .
18. R. C. Cooper, C. Lee, C. A. Marianetti, X. Wei, J. Hone and J. W. Kysar, Nonlinear elastic behavior of two-dimensional molybdenum disulfide, Phys. Rev. B: Condens. Matter Mater. Phys., 2013, 87, 3 Search PubMed .
19. P. Aghdasi, R. Ansari, S. Rouhi, S. Yousefi, M. Goli and H. R. Soleimani, Investigating elastic and plastic characteristics of monolayer phosphorene under atomic adsorption by the density functional theory, Physica B, 2021, 600, 412603 CrossRef CAS .
20. D. Guo, B. Shao, C. Li and Y. Ma, Theoretical insight into structure stability, elastic property and carrier mobility of monolayer arsenene under biaxial strains, Superlattices Microstruct., 2016, 100, 324–334 CrossRef CAS .
21. T. Cheng, Z. Liu and Z. Liu, High elastic moduli, controllable bandgap and extraordinary carrier mobility in single-layer diamond, J. Mater. Chem. C, 2020, 8(39), 13819–13826 RSC .
22. D. Singh, N. Khossossi, W. Luo, A. Ainane and R. Ahuja, 2D Janus and non-Janus diamanes with an in-plane negative Poisson's ratio for energy applications, Mater. Today, 2022, 14, 100225 CrossRef CAS .
23. P. V. Bakharev, M. Huang, M. Saxena, S. W. Lee, S. H. Joo, S. O. Park, J. Dong, D. C. Camacho-Mojica, S. Jin, Y. Kwon, M. Biswal, F. Ding, S. K. Kwak, Z. Lee and R. S. Ruoff, Chemically induced transformation of chemical vapour deposition grown bilayer graphene into fluorinated single-layer diamond, Nat. Nanotechnol., 2020, 15(1), 59–66 CrossRef CAS .
24. F. Piazza, C. Kelvin, M. Monthioux, P. Puech and I. Gerber, Raman evidence for the successful synthesis of diamane, Carbon, 2020, 169, 129–133 CrossRef CAS .
25. H. Zhang, R. Zhang, S. Hu, K. Yang, C. Sun, Q. Wang and Y. Tang, Electroreduction of CO2 on Cu, Fe, or Ni-doped Diamane Sheets: A DFT Study, Chem. – Eur. J., 2024, 30(19), e202303995 CrossRef CAS PubMed .
26. M. J. Szary, Toward high selectivity of sensor arrays: Enhanced adsorption interaction and selectivity of gas detection (N2, O2, NO, CO, CO2, NO2, SO2, AlH3, NH3, and PH3) on transition metal dichalcogenides (MoS2, MoSe2, and MoTe2), Acta Mater., 2024, 274, 120016 CrossRef CAS .
27. S. Fu, Y. Liu, J. Li, L. Wan, N. Gao and H. Li, Degenerate p-Type and n-Type Doping of Diamane by Molecular Adsorption, J. Phys. Chem. C, 2023, 127(20), 9939–9946 CrossRef CAS .
28. M. Fyta, Nitrogen-Vacancy Centers and Dopants in Ultrathin Diamond Films: Electronic Structure, J. Phys. Chem. C, 2013, 117(41), 21376–21381 CrossRef CAS .
29. D. Qiu, Q. Wang, S. Cheng, N. Gao and H. Li, Electronic structures of two-dimensional hydrogenated bilayer diamond films with Si dopant and Si-V center, Results Phys., 2019, 13, 102240 CrossRef .
30. H. Da, Y. P. Feng and G. Liang, Transition-Metal-Atom-Embedded Graphane and Its Spintronic Device Applications, J. Phys. Chem. C, 2011, 115(46), 22701–22706 CrossRef CAS .
31. C.-K. Yang, Graphane with defect or transition-metal impurity, Carbon, 2010, 48(13), 3901–3905 CrossRef CAS .
32. M. Liu, Q. Chen, Y. Huang, C. Cao and Y. He, A first-principles study of transition metal doped arsenene, Superlattices Microstruct., 2016, 100, 131–141 CrossRef CAS .
33. S. Lin, X. Ye, R. S. Johnson and H. Guo, First-Principles Investigations of Metal (Cu, Ag, Au, Pt, Rh, Pd, Fe, Co, and Ir) Doped Hexagonal Boron Nitride Nanosheets: Stability and Catalysis of CO Oxidation, J. Phys. Chem. C, 2013, 117(33), 17319–17326 CrossRef CAS .
34. C. Niu, Y. Cheng, K. Yang, J. Zhang, H. Zhang, Z. Zeng and X. Wang, Boron-dopant enhanced stability of diamane with tunable band gap, J. Phys.: Condens. Matter, 2020, 32(13), 135503 CrossRef CAS .
35. C. Niu, J. Zhang, H. Zhang, J. Zhao, W. Xia, Z. Zeng and X. Wang, Configuration stability and electronic properties of diamane with boron and nitrogen dopants, Phys. Rev. B, 2022, 105(17), 174106 CrossRef CAS .
36. C. Chen, Y. Li, D. Guo, C. Ke, D. Fan, S. Lu, X. Li, M. Jiang and X. Hu, Monodispersed Transition Metals Induced Ordinary-Pressure Phase Transformation from Graphite to Diamond: A First-Principles Calculation, ACS Appl. Mater. Interfaces, 2023, 15(25), 30684–30691 CrossRef CAS .
37. Z. Zhu, C. Jiang, C. Chen, S. Lu, M. Jiang, X. Li and X. Hu, Ordinary-pressure phase transition from graphite to diamond induced by monodispersed Ta atoms, Carbon, 2023, 211, 118098 CrossRef CAS .
38. G. Kresse and J. Furthmuller, Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set, Phys. Rev. B: Condens. Matter Mater. Phys., 1996, 54(16), 11169–11186 CrossRef CAS .
39. G. Kresse and J. Furthmüller, Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set, Comput. Mater. Sci., 1996, 6, 15–50 CrossRef CAS .
40. J. P. Perdew, K. Burke and M. Ernzerhof, Generalized Gradient Approximation Made Simple, Phys. Rev. Lett., 1996, 77(18), 3865–3868 CrossRef CAS PubMed .
41. J. Wang, L. Li, J. Wang, W. Yang, P. Guo, M. Li, D. Liu, H. Zeng and B. Zhao, First-Principles Study on the Nanofriction Properties of Diamane: The Thinnest Diamond Film, Nanomaterials, 2022, 12(17), 2939 CrossRef CAS PubMed .
42. Y. Liu, L. Gao, S. Fu, S. Cheng, N. Gao and H. Li, Highly efficient VOC gas sensors based on Li-doped diamane, Appl. Surf. Sci., 2023, 611, 155694 CrossRef CAS .
43. S. Grimme, S. Ehrlich and L. Goerigk, Effect of the damping function in dispersion corrected density functional theory, J. Comput. Chem., 2011, 32(7), 1456–1465 CrossRef CAS PubMed .
44. S. Grimme, J. Antony, S. Ehrlich and H. Krieg, A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu, J. Chem. Phys., 2010, 132, 15 CrossRef .
45. X. Wang, H. Niu, Y. Liu, C. Shao, J. Robertson, Z. Zhang and Y. Guo, Theoretical investigation on graphene-supported single-atom catalysts for electrochemical CO2 reduction, Catal. Sci. Technol., 2020, 10(24), 8465–8472 RSC .
46. Y.-P. Tian, C.-B. Wang and W.-J. Gong, Arsenene as a promising sensor for the detection of H2S: a first-principles study, RSC Adv., 2023, 13(4), 2234–2247 RSC .
47. P. Radomski and M. J. Szary, Transition metals vs. chalcogens: The impact on NOx adsorption on MoS2, MoSe2 and WS2 transition-metal dichalcogenides, Acta Mater., 2024, 272 Search PubMed .
48. G. Henkelman, B. P. Uberuaga and H. Jónsson, A climbing image nudged elastic band method for finding saddle points and minimum energy paths, J. Chem. Phys., 2000, 113(22), 9901–9904 CrossRef CAS .
49. B. Mortazavi, F. Shojaei, B. Javvaji, M. Azizi, H. Zhan, T. Rabczuk and X. Zhuang, First-principles investigation of mechanical, electronic and optical properties of H-, F- and Cl-diamane, Appl. Surf. Sci., 2020, 528, 147035 CrossRef CAS .
50. F. G. Sen, Y. Qi and A. T. Alpas, Surface stability and electronic structure of hydrogen- and fluorine-terminated diamond surfaces: A first-principles investigation, J. Mater. Res., 2011, 24(8), 2461–2470 CrossRef .
51. D. M. Florjan and M. J. Szary, Enhancing surface activity in MoTe2 monolayers through p-block doping: A comprehensive DFT investigation, Acta Mater., 2024, 272 Search PubMed .
52. C. Chen, J. Cao, W. Yin, Q. Zhang, Y. Yao and X. Wei, Single transition metal atom modified MoSe2 as a promising electrocatalyst for nitrogen Fixation: A first-principles study, Chem. Phys. Lett., 2021, 780 Search PubMed .
53. E. Piosik and M. J. Szary, Development of MoS2 doping strategy for enhanced SO2 detection at room temperature, Appl. Surf. Sci., 2023, 638 Search PubMed .

---

Footnote

† Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4tc02420f

This journal is © The Royal Society of Chemistry 2024