Atomically Dispersed Transition Metals on Holey Graphyne as an Efficient Electrocatalyst for Nitrogen Reduction Reactions

The electrochemical nitrogen reduction reactions (NRR) offer a sustainable alternative to the energy-intensive Haber–Bosch process ammonia synthesis at ambient conditions. In this study, we employ the first-principles density functional theory (DFT) calculations to systematically investigate 3d transition metal-decorated holey graphyne (TM@hGY, TM = Sc-Zn) as single-atom electrocatalysts for NRR. Sc, Ti, V, Cr, and Fe exhibit robust thermodynamic and thermal stability on the hGY substrate among the screened candidate materials. Mechanistic analysis of the NRR pathway reveals that Cr@hGY and Fe@hGY achieve favorable limiting potentials of −0.34 and −0.49 V, respectively, suggesting high catalytic activity. However, Fe@hGY suffers from poor selectivity due to dominant hydrogen evolution reaction activity. Consequently, only Cr@hGY demonstrates high NRR activity, making it the most promising and selective catalyst among the investigated TM@hGY systems for efficient electrochemical ammonia synthesis under ambient conditions. This work provides valuable theoretical insight into the rational design of low-cost, high-performance single-atom catalysts based on 2D carbon frameworks for sustainable ammonia production.