Achieving efficient N2 electrochemical reduction by stabilizing the N2H* intermediate with the frustrated Lewis pairs

Abstract

Electrocatalytic nitrogen reduction reaction (eNRR) with sustainable energy under ambient conditions represents an attractive approach to producing ammonia, but the design of the-state-of-the-art electrocatalyst with high efficiency and selectivity still faces formidable challenges. In contrast to traditional eNRR catalyst design strategies focusing on N≡N triple bond activation, we herein theoretically proposed an alternative strategy to improve eNRR performance via stabilizing the N2H* intermediate using catalysts with the frustrated Lewis pairs (FLPs), i.e., transition metal (TM) atoms and boron (B) atom co-doped 2D black phosphorus (TM-B@BP). Our density functional theory (DFT) results reveal that the TM atom donates electrons to the adsorbed N2 molecule, while B atom provides empty orbital to stabilize the adsorption of N2H* intermediate. This framework successfully identifies five promising candidates (i.e., Ti-B@BP, V-B@BP, Cr-B@BP, Mn-B@BP and Fe-B@BP) with low theoretical limiting potentials (−0.60, −0.41, −0.45, −0.43 and −0.50 V, respectively) and high selectivity for eNRR. We believe that the intermediate stabilization strategy introduced in current work offers a new opportunity to achieve accelerated and cost-effective ammonia synthesis with electrocatalysis.