  The energy demands for the growing development of society need to be catered
with alternative and green fuels like hydrogen energy for a lasting and
sustainable culture. One essential component of the hydrogen economy is the
efficiency of its storage. We have studied the hydrogen-storage capability on a
recently synthesized Biphenylene (BPh) decorated with Sc using the
first-principles density functional theory (DFT) and ab-initio molecular
dynamics (AIMD) techniques. Scandium attaches BPh sheet strongly with binding
energy -3.84 eV, and single Sc decorated on BPh can absorb a maximum of five
H$_2$ molecules resulting in a high gravimetric weight percentage of 11.07,
which is significantly higher than DoE's ultimate criteria (6.5 wt%). Using
van't Hoff equation, strongly and weakly attached hydrogens correspond to
desorption temperatures of 200 K and 397 K with an average of 305 K. The high
binding of Sc to BPh is due to charge donation of 3d orbital of Sc to 2p
orbital of C. The interactions between absorbed H$_2$ and BPh+Sc are due to
charge transfer from 3d-orbital of Sc to ${\sigma}$* bond of H$_2$ molecules
and backdonation from ${\sigma}$ bond of H$_2$ to empty 3d-orbital of Sc known
as Kubas type interaction. Furthermore, phonon and AIMD simulation confirm
BPh+Sc stability, and the presence of an energy barrier shows no probability of
Sc-Sc clustering on BPh. So theoretically stable BPh+Sc showing high
gravimetric weight percentage with an average 305 K desorption temperature,
might be a potential candidate for solidstage hydrogen devices.
