Single boron atom anchored on graphitic carbon nitride nanosheet (B/g-C₂N) as a photocatalyst for nitrogen fixation: A first-principles study

It is essential to explore high efficient catalysts for nitrogen reduction in ammonia production. Based on the first-principles calculation, we find that B/g-C₂N can serve as high performance photocatalyst in N₂ fixation, where single boron atom is anchored on the g-C₂N to form B/g-C₂N. With the introduction of B atom to g-C₂N, the energy gap reduces from 2.45 eV to 1.21 eV and shows strong absorption in the visible light region. In addition, N₂ can be efficiently reduced on B/g-C₂N through the enzymatic mechanism with low onset potential of 0.07 V and rate-determining barrier of 0.50 eV. The "acceptance-donation" interaction between B/g-C₂N and N₂ plays a key role to active N₂, and the BN₂ moiety of B/g-C₂N acts as active and transportation center. The activity originates from the strong interaction between 1π1π^* orbitals of N₂ and molecular orbitals of B/g-C₂N, the ionization of 1π orbital and the filling of 1π^* orbital can increase the N≡N bond length greatly, making the activation of N₂. Overall, this work demonstrates that B/g-C₂N is a promising photocatalyst for N₂ fixation.