Single Boron Atom Anchored on graphitic carbon nitride nanosheet (B/g-C$_2$N) as a photocatalyst for Nitrogen fixation: A First-Principles Study

Abstract

Photocatalytic nitrogen reduction is the promising way for ammonia production, the question now is that the search of highly active and low active catalysts. Based on the first-principles calculation, single boron atom is anchored on the g-C$_2$N to form B/g-C$_2$N, the results show that B/g-C$_2$N can serve as a potential photocatalyst for N$_2$ fixation. The introduction of B atom to g-C$_2$N, the energy gap will reduce from 2.45 eV to 1.21 eV, and also show strong absorption in the visible light region. In addition, N$_2$ can be efficiently reduced on B/g-C$_2$N through the enzymatic mechanism with low onset potential of 0.07 V and rate-determing barrier of 0.50 eV. The "acceptance-donation" interaction between B/g-C$_2$N and N$_2$ plays a key role to active N$_2$, the BN$_2$ moiety of B/g-C$_2$N acts as active and transportation center. And the activity originates from the strong interaction between 1$\pi$1$\pi$* orbitals of N$_2$ and molecular orbitals of B/g-C$_2$N, the ionization of 1$\pi$ orbital and the filling of 1$\pi$* orbital can increase the N$\equiv$N bond length greatly, making the activation of N$_2$. Overall, this work demonstrates B/g-C$_2$N is a promising photocatalyst for N$_2$ fixation.