two flat monolayers as $\alpha_1$-borophene and $\beta_1$-borophene, are energetically most stable 2D boron structures among the state-of-the-art 2D structures of boron [@X.Wu2012].

Recently, a new type of 2D boron Polymorph with an orthorhombic 8-$ Pmmn $ symmetry group, has been predicted to be more stable than the $\alpha$-borophene, that exhibits anisotropic tilted Dirac cones [@zhou2014semimetallic]. A first-principles study reveals that borophene is the first known materials with high-frequency plasmons in the visible spectrum [@Sadrzadeh-NL12]. Furthermore, in this borophene polymorph the anisotropic plasmon modes remain undamped for higher energies along the mirror symmetry direction, in which the anisotropic Friedel oscillation behaves like $r^{-3}$ in the large-$r$ limit [@Sadhukhan2017].

However, theoretical calculations show that due to the imaginary frequencies in its phononic dispersion, the Free-standing 2D borophene ($B_8$) is unstable against long-wavelength periodic vibrations [@Xu16; @Jena2017], needing a substrate to be stabilized. A feasible and effective method to dynamically stable borophene, is the chemical functionalization using surface hydrogenation. First-principles calculations of Xu [*et al.*]{} show that the fully hydrogenation of borophene, called borophane ($B_2H_2$), is a viable method to stabilize borophene in the vacuum without a substrate [@Xu16]. It has also been predicted in this work that borophane has a remarkable Fermi 