Borophane, a derivate of borophene, has been shown to eliminate the phonon imaginary frequency of borophene entirely with enhanced structural stability and be a 2D Dirac material with many appealing properties similar to its counterpart graphene. However, the mechanisms involved in borophene hydrogenation are still unclear, which are essential to borophane fabrication in experimental studies and which benefit our understanding of borophene functionalization. In this work, we investigate H2 adsorption and dissociation with (without) an external field and the subsequent spillover of H atoms on borophene based on density functional theory (DFT) to shed light on the procedure of borophene hydrogenation. We find that the incorporation of positive electric fields could facilitate the borophane formation with shallower energy barriers for H2 decomposition and H atoms present ultrahigh mobility on borophene under positive field. The origin of the field modulated energy barriers has been discussed. Our work provid...