Breaking Scaling Relations and Boosting Ammonia Synthesis in Nitrogen Reduction with V-Containing Heteronuclear Double Metal Atoms

Abstract

The electrochemical nitrogen reduction reaction (NRR), powered by renewable electricity, offers a promising pathway for sustainable ammonia production. To date, the multi-step nature of this reaction introduces inherent challenges due to the well-known scaling relations between the adsorption energies of various intermediates, which limit overall efficiency. By using the density functional theory calculations, in this study we evaluated the NRR activity of dual-metal atoms, specifically vanadium (V) paired with 3d transition metals, anchored on graphdiyne (V-TM@GDY, where TM = Sc ~ Cu). We first found that the adsorption energies of various NRR intermediates were not following the scaling relationships anymore as expected. We further identified an optimized volcano-shaped correlation between electron transfer to the adsorbed N₂ molecule and the limiting potential for ammonia synthesis (UL(NH3)) across all heteronuclear V-TM@GDY dual-atom catalysts (DACs). Intriguingly, through an "acceptance-donation" mechanism to activate the adsorbed N₂, with GDY functioning as an electron reservoir and the V-TM pairs acting as electron transmitters, it is obtained that V-Cr@GDY and V-Fe@GDY exhibit high catalytic activity with low UL(NH3) values of -0.36 V and -0.42 V, respectively, and both DACs also effectively suppress the hydrogen evolution reaction, achieving nearly 100% theoretical Faradaic efficiency for NH₃ production. These findings underscore the critical role of electron transfer during NRR and highlight the potential of V-containing DACs, and will inspire further experimental research in the interesting field.