  The discovery of metals as catalytic centers for nitrogen reduction reactions
has stimulated great enthusiasm for single-atom catalysts. However, the poor
activity and low selectivity of available SACs are far away from the industrial
requirement. Through the high throughout first principles calculations, the
doping engineering can effectively regulate the NRR performance of b-Sb
monolayer. Especially, the origin of activated N2 is revealed from the
perspective of the electronic structure of the active center. Among the 24
transition metal dopants, Re@Sb and Tc@Sb showed the best NRR catalytic
performance with a low limiting potential. The Re@Sb and Tc@Sb also could
significantly inhibit HER and achieve a high theoretical Faradaic efficiency of
100%. Our findings not only accelerate discovery of catalysts for ammonia
synthesis but also contribute to further elucidate the structure-performance
correlations.
