The ammonia decomposition reaction (ADR) can play a key role in advancing carbon-free hydrogen (green hydrogen) applications, using ammonia as a hydrogen carrier that is much easier to transport and store than molecular hydrogen. Although ruthenium-based materials are the most active catalysts for ADR, the large-scale application of the attractive ADR technology is limited by the high price and scarcity of ruthenium. Therefore, developing highly active and stable single atom Ru catalysts with low Ru loading is critical for efficient and low-cost ammonia decomposition technology. Here, we report a new class of reducible mixed metal oxide supports (MgCeAlO4) promoted with an alkali metal (Cs) to generate highly effective channels for hydrogen spillover to remove hydrogen species, generated via ammonia decomposition, from catalytically active sites, increasing turnover frequency. The defects created (due to grain boundaries between oxides) on the support also enhance the Ru dispersion (~73%). The Cs-MgCeAlO4 support significantly enhances catalyst basicity, promotes N2 desorption, and improves the turnover frequency for NH3 decomposition. Ammonia conversions of 99% and 90% were achieved at space velocities of 15,000 and 20,000 mL gcat-1 h-1, respectively, at 400 oC and 1.0 bar. Furthermore, ~90% conversion was achieved at a higher space velocity of 40,000 mL gcat-1 h-1 and an economically feasible temperature of 450 oC. Moreover, the catalyst was shown to be stable at 450 oC for 200 hours, capable of maintaining complete ammonia conversion to hydrogen.
