Ternary synergy and structural effects in Heusler X2YZ (X = Ru, Os) alloys for efficient nitrogen reduction to ammonia.

In this study, we investigated the catalytic activity of Ru- and Os-based Heusler alloys for the nitrogen reduction reaction (NRR). First-principles methods were employed to calculate the adsorption behavior of each intermediate in the NRR on the (110) surfaces of these alloys. These alloys exhibit significantly reduced limiting potentials and superior catalytic performance. The most promising candidate, Ru2HfGa, has a limiting potential for NRR of only -0.34 V and shows higher selectivity for NRR than for the hydrogen evolution reaction (HER). There is a significant deviation between the N2 adsorption energies on these surfaces and the traditional d-band center descriptor. However, by analyzing the synergistic charge transfer behavior among the three atoms, X, Y, and Z, a more accurate predictive relationship for adsorption energies can be established. Additionally, when the radii of some elements are too large, the active sites on these surfaces become inactive, and we finally found the cliff-like linear relationship between the N atom adsorption energy and reaction activity.