velocity which is nearly four times higher than that of graphene.

An [*et al.*]{} using first-principles density functional theory plus the non-equilibrium Green’s function approach, demonstrated that borophane displays a huge electrical and mechanical anisotropy. Along the valley-parallel direction (armchair), the 2D borophane exhibits a metallic treatment with a linear current-voltage curve, in contrast to the perpendicular buckled direction (zigzag), that shows off a semiconductor behavior  [@Anpccp2018].

Similar to hydrogenated graphene, borophene is capable of forming various two-dimensional allotropes due to its valency. Only one case has been reported in literature as far as our knowledge, the chair-like borophane, named C-boropane. It is intriguing to know, whether there are other metastable allotropes with novel electronic characteristics?

Very recently, in a comprehensive study [@WangSci16], the likely formation of borophane with a focused on the structural stability of borophane allotropes, has been provided, based on the first principles calculations. The crystal structure of seven allotropes of borophane, namely Plane-Square-type borophane (PS-borophane), Plane-Triangle-type borophane (PT-borophane), Chair-like borophane (C-borophane), Boat-like borophane (B-borophane), Twist-Chair-Boat-type borophane (TCB-borophane), Triangle-type borophane (T-borophane) and Washboard-like borophane (W-borophane), were identified in this paper [@WangSci16]. The results show that the charge transfer from B atoms to H atoms is crucial for 