N-2 Activation and Reduction on Graphdiyne Supported Single, Double, and Triple boron Atom Catalysts: A First Principles Investigation.

First principles simulations were carried to investigate the activity and selectivity of single, double, and triple boron atom catalysts supported on graphdiyne (GDY) monolayer for N-2 capture and reduction. Our results demonstrate that the double and triple boron atom catalysts bind and activate N-2 molecule effectively with significantly large binding energies of 1.23 and 1.16 eV respectively. In depth density of states analysis revealed that build-up of boron p states near the Fermi level promotes the N-2 binding on the double and triple boron atom catalysts leading to strong overlap between boron and nitrogen p-states. The free energy pathways for nitrogen reduction indicate very low limiting potentials of -0.41 and -0.58 V for the single and triple boron atom catalysts along the alternating pathways whereas the double boron atom catalyst is found to show a very high limiting potential of -3.29 V along the enzymatic pathway. Moreover, as compared to the single boron atom catalyst, the triple boron atom catalyst is found to be effective in suppressing the competitive hydrogen evolution reaction. Thus, we expect that the current work will lead to more investigation for design of transition-metal free catalysts for N-2 conversion to ammonia.