A fundamental understanding of the spillover mechanism is an open and challenging problem and plays an important role in catalysis. In particular, bond-exchange spillover mechanism is considered to be effective for reversible storage and release of hydrogen at near ambient conditions. For this, three critical steps are needed: finding the right support (acceptor), the right catalyst to split H₂, and ensuring that once H₂ is split, the H atoms can migrate on the surface with the help of secondary catalysts and eventually hydrogenate the entire material. In this paper we address these challenges using density functional theory. We show that BH₃, a secondary catalyst, can be produced by symmetrically splitting its stable precursor, B₂H₆, on doped metal-free surfaces such as graphene and h-BN as well as on MOF5. In addition, to reduce computational cost, we develop structural descriptor and predictive model equation to effectively screen potential BH₃ binding sites. Symmetrical splitting of B₂H₆ on different types of materials can address the hydrogen spillover challenge, making efficient storage of hydrogen possible.