Single boron modulated graphdiyne nanosheets for efficient electrochemical nitrogen fixation: a first-principles study

Abstract

The electroreduction of dinitrogen (N₂) is a promising alternative approach for ammonia synthesis under mild conditions. In this work, metal-free electrocatalysts using a single boron atom doped into a graphdiyne (GDY) monolayer are fabricated for N₂ fixation and conversion to NH₃. The NRR electrochemical mechanism has been examined by density functional theory (DFT) calculations. Our calculations revealed that configuration B(S₃)@GDY fabricated using a single boron substituting the diacetylene carbon atom exhibits superior catalytic activity in the nitrogen reduction reaction. The preferred distal pathway of the NRR has an extremely low limiting potential of only 0.27 V. In addition, boron atom doping in GDY results in a small band gap (0.24 eV for B(S₃)@GDY) and redistribution of the electron density. The electron deficient boron atom is largely positively charged, and thus plays a crucial role in the activation of the NN bond. Moreover, the competing HER is effectively suppressed. This work provides an efficient metal-free single atom electrocatalyst for the NRR based on a 2D graphdiyne monolayer.