Identifying the nature of interaction between LiBH_4 and two-dimensional substrates: DFT study with van der Waals correction

摘要

Addressing the nature of interaction at the LiBH_4-carbon interface is the key to unveiling mechanism for the carbon-facilitated desorption of lithium borohydride (LiBH_4). Density functional theory calculations, taking into account the long range dispersion forces, have been performed to explore the interaction between LiBH_4, in the form of either a monomer unit or a crystalline bulk, and two-dimensional (2D) substrate, represented by graphene and hexagonal boron nitride. At the monomer-2D contact, the permanent dipole of LiBH_4 induces polarization of the n electrons of the 2D, and the resultant permanent dipole-induced dipole attraction becomes the main source of binding. At the bulk-2D interface, van der Waals attraction dominates the interfacial binding rather than the dipole-dipole attraction. The absolute values of the calculated interface energy match closely with the surface energy of pristine (001) LiBH_4, hinting that the energy released by the formation of the interface has enough magnitude to overcome the surface energy of LiBH_4.