The Hydrogenation Dynamics of h-BN Sheets
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The Hydrogenation Dynamics of h-BN Sheets
Eric Perim1, Ricardo Paupitz2, P. A. S. Autreto1 and D. S. Galvao1.
1
Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas, 13083-970, Campinas, São Paulo, Brazil. 2
Departamento de Física, IGCE, Universidade Estadual Paulista, UNESP, 130506-900, Rio Claro, SP, Brazil.
ABSTRACT
Hexagonal boron nitride (h-BN), also known as white graphite, is the inorganic analogue of graphite. Single layers of both structures have been already experimentally realized. In this work we have investigated, through fully atomistic reactive molecular dynamics simulations, the dynamics of hydrogenation of h-BN single-layers membranes. Our results show that the rate of hydrogenation atoms bonded to the membrane is highly dependent on the temperature and that only at low temperatures there is a preferential bond to boron atoms. Unlike graphanes (hydrogenated graphene), hydrogenated h-BN membranes do not exhibit the formation of correlated domains. Also, the out-of-plane deformations are more pronounced in comparison with the graphene case. After a critical number of incorporated hydrogen atoms the membrane become increasingly defective, lost its two-dimensional character and collapses. The hydrogen radial pair distribution and second-nearest neighbor correlations were also analyzed.
INTRODUCTION
The advent of graphene [1-3] created a new era in materials science. Graphene [1] is a single-layer of sp2-hybridized hexagonal array of carbon atoms, which exhibits unique
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electronic, structural and mechanical properties. Because of these properties graphene is considered to be one of the most promising materials for a new electronics [2]. However, in its pristine form graphene is a zero bandgap semiconductor, which limits its use in some kind of transistor applications [2-3]. Much effort has been devoted to try to find a route to open, in a controlled way, a gap in the graphene band structure. The most common strategies explore physical and chemical methods, including chemical modifications through hydrogenation [4-6] and fluorination [7-8]. Hydrogenated graphenes are called graphanes [5] and fluorinated ones, fluorographenes [7-8]. The success of these approaches to solve the graphene bandgap problem has been only partially achieved [4-8]. In part because of this there is a renewed interest in other graphene-like structures, as for example, in the hexagonal boron nitride (h-BN) [9-10]. h-BN, also known as inorganic graphite or white graphite, is the structural analogue of graphite, presenting the same morphology of pilled up honeycomb sheets. Even the interlayer and bond distances are almost identical, the only important structural difference being the layer stacking order. However, the synthesis of BN structures are, in general, difficult and only recently h-BN monolayers (the equivalent to graphenes) have been obtained [9-12]. In this work we have investigated the dynamics of hydrogenation of h-BN single-layer (what would be the inorganic equivalent of graphanes, the hydro
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