Design of Alkaline Earth-Doped Co/MgO Catalysts for High-Performance Ammonia Decomposition

Hydrogen is expected to be used as a fuel additive to ammonia, a non-flammable and carbon-free fuel, to improve combustion efficiency. However, the design strategies for developing highly active, non-precious metal catalysts for ammonia decomposition are not yet well understood. Here, we show that Co/Ba0.01Mg0.99O exhibits high activity, with an ammonia conversion of 94.4% and a hydrogen production rate of 3.80 mol gcat-1 h-1 at 500 °C with a WHSV of 60,000 mL gcat-1 h-1. Comparison of the dopant effect of alkaline earth metal elements elucidates that high activity of the Co/Ba0.01Mg0.99O is ascribed to the strong basicity of BaO, formation of Co-BaO core-shell structure, which does not occur with other alkaline earth elements, and their synergistic effect to donating electrons from accumulated BaO to N-Co bond to promote N2 formation which is the rate determining step for ammonia decomposition. Our findings will contribute to the development of cost-effective core-shell type metal catalysts for hydrogen production through ammonia decomposition, leading to the realization of a carbon neutral society in which ammonia plays a key role.