Intrinsic and Dynamically Generated Nitrogen Vacancies Boost Ammonia Decomposition over Ru/TiN Catalyst

Ammonia (NH 3 ) is widely recognized as a promising hydrogen (H 2 ) carrier for storage and transport, with its decomposition playing a pivotal role in the hydrogen–ammonia energy cycle by enabling carbon-free H 2 generation. However, the intrinsic corrosivity of NH 3 often leads to structural degradation of catalysts, while the excessive hydrogen species produced during decomposition can block active sites, making N–H bond cleavage kinetically challenging. Here, we report a nitrogen-vacancy-rich Ru/TiN catalyst that maintains structural integrity and enhances N–H bond activation. This is achieved through the formation of stable Ru–N–Ti interfacial structures and the in situ generation of additional nitrogen vacancies during the reaction. The synergistic effect of intrinsic and dynamically generated vacancies enables a 20-fold increase in catalytic activity compared to oxide-supported Ru catalysts, along with enhanced thermal stability and long-term operational durability over extended reaction periods.