LAUSR

The present work investigates the binding of atomically dispersed transition metals to the perfect and single/double vacancy (SV/DV)-containing defective β12 -borophenes and the catalytic performance of those corresponding single-atom catalysts (SACs) and diatomic catalysts (DACs) for nitrogen reduction reaction (NRR) by means of density functional theory calculations. Although previous theoretical studies proposed that the inherent hexagon hole of the defect-free β12 -borophene is capable of anchoring single metal atom for NRR, our calculations suggest that the interaction between borophene and doped metal is not strong enough to avoid metal aggregation. For the defective β12 -borophene with a SV, despite the single metal can be stabilized in an 8-membered ring, we find the SAC is still ineffective for NRR because of the competitive hydrogen evolution process. Regarding to the DV-containing β12 -borophene, a defective configuration with an unexpected 11-membered hole is proved as the most stable structure which possesses a very similar average atomic energy (6.25 eV/atom) compared to that of the pristine β12 sheet (6.26 eV/atom). We find two metal atoms can be encapsulated into the confined-space of the B11 ring. Compared to SACs, those corresponding DACs are more active for N2 fixation and hydrogenation, and the hydrogen evolution reaction can be passivated, attributing to the synergistic effect of dual metal centers. Among all candidates, the V2/β12 -DV is predicted as the most readily catalyst for NRR, with the limiting potential of as low as 0.15 V.