Single and double boron atoms doped nanoporous C₂N–<i>h</i>2D electrocatalysts for highly efficient N₂ reduction reaction: a density functional theory study

Abstract

The electrocatalytical process is the most efficient way to produce ammonia (NH₃) under ambient conditions, but developing a highly efficient and low-cost metal-free electrocatalysts remains a major scientific challenge. Hence, single atom and double boron (B) atoms doped 2D graphene-like carbon nitride (C₂N-h2D) electrocatalysts have been designed (B@C₂N and B₂@C₂N), and the efficiency of N₂ reduction reaction (NRR) is examined by density functional theory calculation. The results show that the single and double B atoms can both be strongly embedded in natural nanoporous C₂N with superior catalytic activity for N₂ activation. The reaction mechanisms of NRR on the B@C₂N and B₂@C₂N are both following an enzymatic pathway, and B₂@C₂N is a more efficient electrocatalyst with extremely low overpotential of 0.19 eV comparing to B@C₂N (0.29 eV). In the low energy region, the hydrogenation of N₂ is thermodynamically more favorable than the hydrogen production, thereby improving the selectivity for NRR. Based on these results, a new double-atom strategy may help guiding the experimental synthesis of highly efficient NRR electrocatalysts.