Electronic structure study on 2D hydrogenated Icosagens nitride nanosheets

Superlattices and Microstructures 76 (2014) 213–220

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Electronic structure study on 2D hydrogenated Icosagens nitride nanosheets S. Ramesh a,⇑, S. Marutheeswaran b, Jerald V. Ramaclus c, Dolon Chapa Paul a a b c

Saveetha School of Engineering, Saveetha University, Thandalam, Chennai 605012, India Department of Chemistry, Pondicherry University, Pondicherry 605014, India Department of Electrical Engineering, University of Chile, Santiago 8370451, Chile

a r t i c l e

i n f o

Article history: Received 16 July 2014 Received in revised form 15 September 2014 Accepted 17 September 2014 Available online 12 October 2014 Keywords: Nanosheet Band structure Density of states Semiconductor Hydridic surface

a b s t r a c t Metal nitride nanosheets has attracted remarkable importance in surface catalysis due to its characteristic ionic nature. In this paper, using density functional theory, we investigate geometric stability and electronic properties of hydrogenated Icosagen nitride nanosheets. Binding energy of the sheets reveals hydrogenation is providing more stability. Band structure of the hydrogenated sheets is found to be n-type semiconductor. Partial density of states shows metals (B, Al, Ga and In) and its hydrogens dominating in the Fermi region. Mulliken charge analysis indications that hydrogenated nanosheets are partially hydridic surface nature except boron nitride. Ó 2014 Elsevier Ltd. All rights reserved.

1. Introduction Nanosheets become a most important materials after the discovery of graphene. Graphene, a 2D extended honeycomb network of sp2 hybridized carbon compound has attracted much attention in nanoscience [1,2] due to their possible applications in many emerging fields such as electronic devices [3], gas sensors [4], transparent conductors [5] and biological applications [6]. The impressive advancement in graphene research has inspired scientists to explore the properties of several 2D planar materials [7,8]. These 2D nanosheets are now considered to be an excellent candidates for ⇑ Corresponding author at: Department of Chemistry, Saveetha School of Engineering, Saveetha University, Thandalam, Chennai 605012, India. Tel.: +91 9894437744. E-mail addresses: [email protected], [email protected] (S. Ramesh). http://dx.doi.org/10.1016/j.spmi.2014.09.034 0749-6036/Ó 2014 Elsevier Ltd. All rights reserved.

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future electronic applications such as high-Tc superconductors [9], optical [10], semiconductor [11] and magnetic superlattices [12]. Recently, researchers have also extended the 2D inorganic nanosheets, such as metals (Si [13], Ge [14]), metal oxides (ZnO [15], MgO [16] TiO2 [17]), metal nitrides (BN [18–20], AlN [21,22], GaN [23,24]), and metal disulfides (MoS2 [25], WS2 [26]) are the major interest to experimental as well as theoretical chemists [27,28]. Among these, Icosagens nitride (Group III-nitrides) nanosheets have been referred to be a potential equivalent of graphene owing to its various reasons like analogous lattice parameters, more resistant to oxidation, chemical and thermal stability [29,30]. Hydrogenation on nanosheets, is a current pursuit due to many of its remarkable properties it also known to decreases the internal stress, it alters the electronic, optical and magnetic properties. In addition BN [31–34], AlN [35,36], and GaN [37,38], a binary compounds are experimentally synthesized in single and multiple layers and are widely used in semiconductor devices, however, only a few reports on fully hydrogenated sheets such as C [39–41], Si [41–43], Ge [41] BN [44–46], and AlN [47] are studied and other sheets are very limited, no periodic trends have been reported. So, it is worth looking into the possibility of fully hydrogenated group III nitride nanosheets, as in the same spirit as graphane and silicane [48]. In this paper, we report the density functional theory calculations to study the structural and electronic properties of fully hydrogenated Icosagens nitride (Ha–MN–Hb; M = B, Al, Ga and In) nanosheets. 2. Computational methods The structural optimizations and electronic calculations were performed using Accelrys package with CASTEP code [49], which is based on density functional theory (DFT) and plane-wave pseudo potential method. The local density approximation (LDA) [50] form was adopted in the calculations. The cutoff energy for the plane wave basis was set to be 400 eV. All geometry optimizations and electronic structure calculations such as band structure, density of states and Mulliken charge population were performed using periodic boundary conditions, and Brillouin zone integrations are performed using a 7  7  1 Monkhorst–Pack (MP) [51]. MP grids were also used for the calculation of the density of states (DOS). The criterion of convergence for the residual forces is set to be less than 0.01 eV/Å and the change of total energy less than 5  106 eV. The interlayer distance is set to more than 10 Å to avoid the interaction between the layers. 3. Result and discussion 3.1. Structure The hydrogenated group III-nitride nanosheets are found to be similar structural lattice of graphane. In that, Nitrogen atoms and group III atoms are arranged in a honeycomb network of sp3 hybridized 2D layers [8]. Fig. 1 represents the optimized structure of Ha–MN–Hb (M = B, Al, Ga and In) single layer nanosheets, which resembles pristine graphane sheet where each M and N atom is bonded to one N and M atoms respectively. In all the layers both M and N atoms are passivized by hydrogen in the polar surface Ha–M and Hb–N with bond lengths of 1.204–1.717 Å and 1.048–1.036 Å, respectively from

Fig. 1. (a) Optimized structure and (b) side view of 2D Ha–MN–Hb (M = B, Al, Ga and In) nanosheet.

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BN–InN. The bond length is relaxed from planar sheet into a buckled sheet. The buckling behaviour overcomes the vanderwals interfaces among the adjacent sheets. The buckling height of the sheets show an increase of 0.503–0.794 from BN to InN hydrogenated sheets. Apparently, the bond length of the metal hydrides (Ha–M) is larger than that of Hb–N due to the difference in bonding character. The interlayer distance of the sheets are fixed 15 Å to avoid interactions between them. The lattice parameters are observed to increases from BN sheet to InN hydrogenated sheet due to the increase in atomic radius of group III atoms. 3.2. Binding energy In order to find the stability of the sheets the binding energy (Eb–H) were calculated using the following relationship (1) [52].

Eb—H ¼ ½E2HþMN sheet  ðEMN sheet þ 2EH Þ=2

ð1Þ

where Eb–H is the binding energy of Ha–MN–Hb sheets, E2H+MN sheet is the energy of group III-nitride sheet bonded with 2H atoms, EMN sheet is the energy of group III-nitride sheet alone and EH is the energy of a free atom in the same lattice. The binding energy of the sheets are reported in Table 1. The binding energy decreases with increase in the bond length of M–N and M–Ha of Ha–MN–Hb sheets. The negative value of Eb–H indicates that the hydrogenation is an exothermic reaction and it can be obtained by the reaction of MN sheets with atomic hydrogen atoms. The low binding energy shows that hydrogenated sheets are stable and extra energy is required to decompose the structure of the nanosheet into atoms [53]. 3.3. Electronic structure We systematically investigated the band structure and partial density of states (PDOS) of Ha–MN–Hb (M = B, Al, Ga and In) nanosheets are shown in Fig. 2. The zero point energy of Fermi energy level represented in speckled line in Fig. 2. The distance between highest point of Fermi energy level in valence band (VB) and the lowest point of the conduction band (CB) is used to determine the energy required for an electron to move valence band to conduction band, which is also known as the forbidden band or the band gap. The band gap of the hydrogen passivized sheets are smaller than the corresponding dehydrogenated sheets this reveals the hydrogenation of nanosheets alters the band structure. The band gap comparison of Ha–MN–Hb (M = B, Al, Ga and In) nanosheets are given in Table 1. In all the four sheets the VB shows degeneracy at the Fermi level. The band structure of all the hydrogenated sheets exhibits direct band gap with the VB maximum and conduction band CB minimum at the C point except the Ha–AlN–Hb which shows indirect band gap with the VB maximum at k point and CB minimum at C point. The VB electrons are contributing more at the Fermi level than the CB electrons in Ha–MN–Hb (M = B, Al, Ga and In) sheets this concludes sheets are n-type semiconductors within the range 2.3–3.4 eV as shown in Table 1.

Table 1 Lattice parameters, bond length, buckling distance, band gap and binding energy of Ha–MN–Hb (M = B, Al, Ga and In) nanosheet. Sheets

HaBNHb

HaAlNHb

HaGaNHb

HaInNHb

a and b (Å) c (deg) dN–Hb (Å) dM–N (Å) dM–Ha (Å) Buckling distance (D) (Å) Band gap HaMNHb Band gap MN Eb–H (eV)

2.547 120 1.048 1.554 1.204 0.503 3.320 4.618 0.05

3.066 120 1.039 1.895 1.569 0.674 2.684 3.103 0.46

3.145 120 1.036 1.949 1.541 0.709 3.264 2.438 1.02

3.489 120 1.036 2.165 1.717 0.794 2.360 2.439 1.36

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Fig. 2. Band structure and partial DOS for fully hydrogenated Ha–MN–Hb (M = B, Al, Ga and In) nanosheet.

The electronic structure of the sheets can further explained by PDOS. It is observed in PODS, the group III-metals orbitals (B, Al, Ga and In) contribution is substantially more in all sheets. Especially, the conduction bands belong to M-2P orbital of group III-metals and this contribution is more than M-2S orbitals except the Ha–BN–Hb where the metal contribution is less in CB. At the same time other than Ha–BN–Hb sheet nitrogen contribution is more dominating in the VB region in all the sheets. These indicates the electrons transfer from nitrogen to metal. Interestingly the hydrogen atoms are arranged in two different chemical environment in all the sheets. One type of the H atom (Ha) is connected to M atom and another type H atom (Hb) is connected to N atom periodically. The metal hydrates (the hydrogen with metals) are playing crucial role at the Fermi region than N–Hb. 3.4. Mulliken population Mulliken charge population analysis revels that the hydrogen atom attached to the metal is very active compared to hydrogen atoms with nitrogen which resembles with PDOS results. The Mulliken

Table 2 Mulliken charge population of Ha–MN–Hb (M = B, Al, Ga and In) nanosheet. Sheets

M

N

Ha

Hb

HaBNHb HaAlNHb HaGaNHb HaInNHb

0.33 1.24 0.90 0.96

0.76 1.36 1.07 1.11

0.13 0.19 0.13 0.17

0.30 0.30 0.30 0.32

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Debye Temperature (θD) (K)

(a) 6000

217

Ha-BN-Hb Ha-AlN-Hb Ha-GaN-Hb Ha-InN-Hb Ha-C-Hb Graphene

5000 4000 3000 2000 1000 0 0

1000

2000

3000

4000

Temperature (K)

(b)

12

Entropy

9

Energy (eV)

6 3

Enthalpy

0

Ha-BN-Hb Ha-AlN-Hb Ha-GaN-Hb Ha-InN-Hb Ha-C-Hb Graphene

-3 -6 -9 -12 0

1000

Free Energy

2000

3000

4000

Temperature (K)

Lattice heat capacity (cal/cell·K)

(c) 25 20

15

10

Ha-BN-Hb Ha-AlN-Hb Ha-GaN-Hb Ha-InN-Hb Ha-C-Hb Graphene

5

0 0

1000

2000

3000

4000

Temperature (K) Fig. 3. (a) Debye temperature (hD ), (b) enthalpy, entropy, and free energy, (c) lattice heat capacity (Cv) of fully hydrogenated Ha– MN–Hb (M = B, Al, Ga and In) nanosheet.

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charge for the atoms in Ha–MN–Hb (M = B, Al, Ga and In) nanosheets are listed in Table 2. Except boron atom bonded with Ha shows ionic in nature due to the negative Mulliken population charge. The Hb bonded with nitrogen shows positive charge indicates covalent nature. These arrangements of hydrogens enables two different type of surface in the nanosheets. The Hb surface acts as regular and another side of the sheet Ha surface act as hydridic nature which leads to several essential applications like DNA cleavage materials, hydrogen gas evolution, energy storage, and metal hydrogen catalyst. 3.5. Thermodynamic properties Thermodynamic properties of the sheets were studied by Debye temperature (hD ), entropy (S) enthalpy (H), free energy (F) and lattice heat capacity (Cv) using CASTEP phonon calculation. Debye temperature (hD ) is generally employed to identify the high and low temperature areas of solids and the strength of covalent nature of crystals. Debye temperature at a given temperature is obtained by calculating the actual heat capacity ðC D Þ by the following Eq. (2).

hD ðTÞ ¼ T

$ Z 9Nk C Dv

0

xD=T

x4ex ðex  1Þ2

%1=3 dx

ð2Þ

where N is the number of atoms per cell, k is Boltzmanns constant. When T > hD , all vibration modes have an energy of kBT in other words, heat capacity of the material tends to be a fixed value. As soon as T < hD , all high frequency modes fail and the materials heat capacity decreases as the temperature decreases. So, Debye temperature own a critical physical meaning the higher Debye temperatures characteristically recommend superior mechanical strength and thermodynamic stability. Fig. 3(a) shows Debye temperature plot of Ha–MN–Hb (M = B, Al, Ga and In) nanosheets compared with graphane and graphene sheets at in the range of 0–4000 K. Debye temperature of the nanosheets possess high value of 2593, 2852, 6000 and 2132, 3746 and 3582 K for hydrogenated BN sheet to graphene sheet respectively. Hence, the hydrogenated nanosheets are stable at high temperature. The hydrogenated GaN sheet have high Debye temperature of 6000 K among all sheets even at 4000 K it was not shown saturation. The entropy as a function of temperature is a significant measure in thermodynamic modelling. Fig. 3(b) shows the relationships between entropy enthalpy and free energy. Once temperature increases, enthalpy and entropy increases, whereas free energy decreases. This indicates increase in internal energy of the system at high temperatures due to disorder in the structure. The calculated values of entropy at 300 K for Ha–MN–Hb (M = B, Al, Ga and In), graphane and graphene are 8.75, 10.68, 9.48, 11.77, 7.98 and 4.36 eV respectively. Furthermore, Fig. 3(c) shows the lattice heat capacity and temperature relationship for nanosheets. The temperature range in between 0 and 2200 K the heat capacity increases dramatically as the temperature increases, and become constant above 2500 K The heat capacity of the sheets are 22.2, 23.1, 20.5, 23.3, 11.5, 22.7 and 11.04 cal/cell K of hydrogenated BN to graphene respectively. Among the four hydrogenated sheet GaN sheet have high heat capacity while InN in lower heat capacity. 4. Conclusion In conclusion, the structural and electronic, properties of Ha–MN–Hb (M = B, Al, Ga and In) nanosheets have been studied. The low binding energy indicates that the hydrogen decorated sheets could be synthesised and in to a very stable form. The results of the fully decorated hydrogen sheets show ntype semiconductor with direct band gap except HaAlNHb sheet which appears to be an indirect band gap semiconductor. The partial density of states of the sheets are conforms that metal hydrate and metal orbitals are dominated in valence band. The Mulliken charge of the atoms proves that two types of surfaces in the sheets is used to several applications like DNA cleavage materials, hydrogen gas evolution, energy storage, and metal hydrogen catalyst. The thermodynamic studies evidenced the sheets are stable at high temperature.

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Acknowledgement The authors are grateful to Dr. Musiri M. Balakrshnarajan for the help of Materials studio calculation.

References [1] M. Osada, T. Sasaki, Exfoliated oxide nanosheets new solution to nanoelectronics, J. Mater. Chem. 19 (2009) 2503–2511. [2] Y. Zhang, Y.W. Tan, H.L. Stormer, P. Kim, Experimental observation of the quantum Hall effect and Berrys phase in graphene, Nature 438 (2005) 201–204. [3] A.K. Geim, K.S. Novoselov, The rise of graphene, Nat. Matter 6 (2007) 183–191. [4] F. Schedin, Detection of individual gas molecules adsorbed on graphene, Nat. Matter. 6 (2007) 652–655. [5] S. Eigler, A new parameter based on graphene for characterizing transparent, conductive materials, Carbon 47 (2009) 2936–2939. [6] M.S. Xu, D. Fujita, N. Hanagata, Conductance of single thiolated poly (GC)-poly (GC) DNA molecules, Small 5 (2009) 2638– 2649. [7] M. Pumera, C.H.A. Wonga, Graphane and hydrogenated graphene, Chem. Soc. Rev. 42 (2013) 5987–5995. [8] X. Mingsheng, T. Liang, S. Minmin, C. Hongzheng, Graphene like two dimensional materials, Chem. Rev. 113 (2013) 3766– 3798. [9] F.R. Gamble, B.G. Silbernagel, Anisotropy of the proton spinlattice relaxation time in the superconducting intercalation complex TaS2 (NH3) structural and bonding implications, J. Chem. Phys. 63 (1975) 2544–2552. [10] M. Liu, X. B Yin, E.U. Avila, B.S. Geng, T. Zentgraf, L. Lu, F. Wang, X. Zhang, A graphene based broadband optical modulator, Nature 474 (2011) 64–67. [11] Y.M. Lin, C. Dimitrakopoulos, K.A. Jenkins, D.B. Farmer, H.Y. Chiu, A. Grill, P. Avouris, Science 327 (2010) 662. [12] J. Zhou, Q. Wang, Q. Sun, X.S. Chen, Y. Kawazoe, P. Jena, Ferromagnetism in semihydrogenated graphene sheet, Nano Lett. 9 (2009) 3867–3870. [13] B. Lalmi, H. Oughaddou, H. Enriquez, A. Kara, S.B. Vizzini, B.N. Ealet, B. Aufray, Epitaxial growth of a silicene sheet, Appl. Phys. Lett. 97 (2010) 223109–223110. [14] S. Cahangirov, M. Topsakal, E. Akturk, H. Sßahin, S. Ciraci, Two and one dimensional honeycomb structures of silicon and germanium, Phys. Rev. Lett. 102 (2009) 236804–236807. [15] S. Vempati, J. Mitra, P. Dawso, Lett. One step synthesis of ZnO nanosheets: a blue white fluorophore, Nanoscale Res. 7 (2012) 470–479. [16] C.L. Yan, D.F. Xue, Novel self-assembled MgO nanosheet and its precursors, J. Phys. Chem. B 109 (2005) 12358–123561. [17] B. Hao, Y. Yan, X. Wang, G. Chen, Synthesis of anatase TiO2 nanosheets with enhanced pseudocapacitive contribution for fast lithium storage, ACS Appl. Mater. Interf. 5 (2013) 6285–6291. [18] Y. Ding, Y. Wang, S. Shi, W. Tang, Electronic structures of porous graphene, BN, and BC2N sheets with one and two hydrogen passivations from first Principles, J. Phys. Chem. C 115 (2011) 5334–5343. [19] D. Pacile, J.C. Meyer, C.O. Girit, A. Zettl, The two dimensional phase of boron nitride few atomic layer sheets and suspended membranes, Appl. Phys. Let. 92 (2008) 133107–133112. [20] Y. Lin, J.W. Connell, Advances in 2D boron nitride nanostructures nanosheets, nanoribbons, nanomeshes, and hybrids with graphene, Nanoscale 4 (2012) 6908–6939. [21] C.W. Zhang, First-principles study on electronic structures and magnetic properties of AlN nanosheets and nanoribbons, J. Appl. Phys. 111 (2012) 043702–043707. [22] Y. Mei, D.J. Thurmer, C. Deneke, S. Kiravittaya, Y. F Chen, A. Dadgar, F. Bertram, B. Bastek, A. Krost, J. Christen, Fabrication, self-assembly, and properties of ultrathin AlN/GaN porous crystalline nanomembranes tubes, spirals, and curved sheets, ACS Nano 3 (2009) 1663–1668. [23] T. Miyazaki, K. Takada, S. Adachi, K. Ohtsuka, Properties of radio frequency sputter deposited GaN films in a nitrogen/ hydrogen mixed gas, J. Appl. Phys. 97 (2005) 093516. [24] E.C.K. Davies, S. J Henley, J.M. Shannon, S.R.P. Silva, Improved optical and electrical properties of low temperature sputtered GaN by hydrogenation, J. Appl. Phys. 99 (2006) 036108. [25] Y. Yu, S.Y. Huang, Y. Li, S.N. Steinmann, W. Yang, L. Cao, Layer dependent electrocatalysis of MoS2 for hydrogen evolution, Nano Lett. 14 (2014) 553–558. [26] J. Yang, D. Voiry, S.J. Ahn, D. Kang, A.Y. Kim, M. Chhowalla, H.S. Shin, Two dimensional hybrid nanosheets of tungsten disulfide and reduced graphene oxide as catalysts for enhanced hydrogen evolution, Angew. Chem. Int. Ed. 52 (2013) 13751–13754. [27] H. Okamoto, Y. Sugiyama, H. Nakano, Synthesis and modification of silicon nanosheets and other silicon nanomaterials, Chem. Eur. J. 17 (2011) 9864–9887. [28] A.J. Du, Z.H. Zhu, Y. Chen, G.Q. Lu, S.C. Smith, First principle study of AlN nanoribbon, Chem. Phys. Lett. 469 (2009) 183– 185. [29] K.S. Novoselov, A.K. Geim, S.V. Morozov, D. Jiang, M.I. Katsnelson, I.V. Grigorieva, S.V. Dubonos, A.A. Firsov, Two dimensional gas of massless diracfermions in graphene, Nature 438 (2005) 197–200. [30] C. Berger, Z. Song, X. Li, X. Wu, N. Brown, C. Naud, D. Mayou, T. Li, J. Hass, A.N. Marchenkov, E.H. Conrad, P.N. First, W.A.D. Heer, Electronic confinement and coherence in patterned epitaxial graphene, Science 312 (2006) 1191–1196. [31] X. Wang, C. Zhi, Q. Weng, Y. Bando, D. Golberg, Boron nitride nanosheets novel syntheses and applications in polymeric composites, J. Phys. Conf. Ser. 012003 (2013) 471–480. [32] X. Wang, A. Pakdel, J. Zhang, Q. Weng, T. Zhai, C. Zhi, D. Golberg, Y. Bando, Large surface-area BN nanosheets and their utilization in polymeric composites with improved thermal and dielectric properties, Nanoscale Res. Lett. 7 (2012) 662.

220

S. Ramesh et al. / Superlattices and Microstructures 76 (2014) 213–220

[33] Y. Lin, T. V Williams, J.W. Connell, Soluble, Exfoliated hexagonal boron nitride nanosheets, J. Phys. Chem. Lett. 1 (2010) 277–283. [34] Y. Lin, T. V Williams, T.B. Xu, W. Cao, H.E.E. Ali, J.W. Connell, Aqueous dispersions of few layered and mono layered hexagonal boron nitride nanosheets from sonication assisted hydrolysis critical role of water, J. Phys. Chem. C 115 (2011) 2679–2685. [35] X. Zhang, Z. Liu, S. Hark, Synthesis and optical characterization of single crystalline AlN nanosheets, Solid State Commun. 143 (2007) 317–320. [36] G. Zhifang, W. Yizao, L. Honglin, An efficient route for the synthesis of aluminium nitride/graphene nanohybrids, J. Am. Ceram. Soc. 97 (2014) 1966–1970. [37] Z.R. Dai, Z.W. Pan, Z.L. Wang, Nanobelts of semiconducting oxides, J. Phys. Chem. B 106 (2002) 902–904. [38] G. Pan, M.E. Kordesch, P.G.V. Patten, Room temperature synthesis of GaN nanopowder, Chem. Mater. 18 (2006) 5392– 5394. [39] C. Wufeng, Z. Zhiye, L. Sirong, C. Chunhua, Y. Lifeng, Efficient preparation of highly hydrogenated graphene and its application as a high performance anode material for lithium ion batteries, Nanoscale 4 (2012) 2124–2129. [40] F.W. Averill, James R. Morris, Valentino R. Cooper, Calculated properties of fully hydrogenated single layers of BN, BC2N, and graphene graphane and its BN-containing analogues, Phys. Rev. B 80 (2009) 195411–195418. [41] J.C. Garcia, D.B. de Lima, L.V.C. Assali, J.F. Justo, Group IV graphene and graphane like nanosheets, J. Phys. Chem. C 115 (2011) 13242–13246. [42] J.T. Tanskanen, M. Linnolahti, A.J. Karttunen, T.A. Pakkanen, Hydrogenated monolayer sheets of group 13–15 binary compounds structural and electronic characteristics, J. Phys. Chem. C 113 (2009) 229–234. [43] G.G. Guzman Verri, L.C. Lew Yan Voon, Band structure of hydrogenated Si nanosheets and nanotubes, J. Phys. Condens. Matter. 23 (2011) 145502–145505. [44] S. Azevedo, J.R. Kaschny, Hydrogenated BN monolayers a first principles study, Eur. Phys. J. B 86 (2013) 395–396. [45] A. Bhattacharya, S. Bhattacharya, C. Majumder, G.P. Das, First principles prediction of the third conformer of hydrogenated BN sheet, Phys. Status Solidi RRL 4 (2010) 368–370. [46] Y. Wang, Electronic properties of two-dimensional hydrogenated and semihydrogenated hexagonal boron nitride sheets, Phys. Status Solidi RRL 4 (2010) 34–36. [47] C.W. Zhang, P.J. Wang, Tuning electronic and magnetic properties of AlN nanosheets with hydrogen and fluorine firstprinciples prediction, Phys. Lett. A 375 (2011) 3583–3587. [48] X. Mingsheng, L. Tao, S. Minmin, C. Hongzheng, Graphene like two dimensional materials, Chem. Rev. 113 (2013) 3766– 3798. [49] M.D. Segall, P.J.D. Lindan, M.J. Probert, C.J. Pickard, P. Hasnip, S.J. Clark, M.C. Payne, First-principles simulation: ideas, illustrations and the CASTEP code, J. Phys. Condens. Matter. 14 (2002) 2717–2744. [50] J.P. Perdew, A. Zunger, Self-interaction correction to density functional approximations for many electron systems, Phys. Rev. B 23 (1981) 5048. [51] H.J. Monkhorst, J.D. Pack, Special points for Brillouin zone integrations, Phys. Rev. B 13 (1976) 5188–5192. [52] Z.M. Ao, F.M. Peeters, A catalyst for hydrogenation of graphene, Appl. Phys. Lett. 96 (2010) 253106–253113. [53] P. Yang, W.H. Bin, Optimized geometry and electronic structure of graphyne like silicyne nanoribbons, Chinese Phys. B 22 (2013) 057303–057304.