The role of single-boron of N-doped graphene for effective nitrogen reduction

Room-temperature electrocatalytic nitrogen reduction reaction (NRR) is of paramount significance for the fertilizer industry and fundamental catalysis science. However, many NRR catalysts were based on the use of metals. Herein, we focus on exploring boron-based, metal-free, efficient catalysts for NRR by density functional theory calculations with van der Waals corrections (DFT + D3). Our results show that the NRR performance of the boron active site can be improved by tuning the N-coordination environment in a graphene sheet, and the B-N-C structures show excellent stability. By considering the correlation between the Bader charges of the boron dopant over N-decorated graphene and their NRR activities, the rational design principle of a boron-based catalyst for NRR is developed. The boron-site with one pyridinic nitrogen in a double-vacancy structure is found to be a highly active center, with low reaction energy (0.53 eV) and kinetic barrier (0.84 eV) through the distal mechanism. We also found that the charge loss of boron considerably hampers hydrogen adsorption, which in turn promotes the NRR efficiency by hindering the competing hydrogen evolution. This work offers new insights into developing low-cost, highly effective boron-based materials as promising electrocatalysts for green ammonia synthesis.(c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

In this study, boron-based, metal-free catalysts for room-temperature electrocatalytic nitrogen reduction reaction (NRR) were explored using density functional theory calculations. The results showed that the NRR performance of the boron active site could be improved by tuning the N-coordination environment on a graphene sheet, and the B-N-C structures exhibited excellent stability. By considering the correlation between the Bader charges of the boron dopant and their NRR activities, a rational design principle for boron-based catalysts for NRR was developed. The study also revealed that the charge loss of boron hindered hydrogen adsorption and promoted NRR efficiency by inhibiting competing hydrogen evolution.