Probing Vacancy-Mediated N₂ Activation on LaN Catalysts via N and La RIXS

Ammonia synthesis is limited by the strong N≡N bond. Lanthanum nitride (LaN) is a promising catalyst owing to its electride-like structure [1, 2] and its ability to stabilise nitrogen vacancies (VN), which provide electron-rich sites that donate charge into the N2 π* orbital. In our previous session at ID32 and MAX IV, we observed vibrationally resolved N K-edge RIXS of adsorbed N2, showing a dissociation energy reduction from 9.6 to 5.2 eV. However, the relationship between VN formation, La 5d–N 2p hybridisation, and N₂ hydrogenation remains unresolved. We developed a mini-reactor allowing catalysts to be treated under reaction conditions (N2+H2, RT–600 °C) with inert transfer to the beamline. Using ID32 high-throughput RIXS, we will map potential energy surfaces, track vacancy-driven electron transfer, and capture transient N–H intermediates.