Single‐Atom Barium Promoter Enormously Enhanced Non‐Noble Metal Catalyst for Ammonia Decomposition

Abstract As a well‐established topic, single‐atom catalyst has drawn growing interest for its high utilization of metal. However, researchers prefer to develop various active metals with single‐atom form, the intrinsic roles of single‐atom promoters are usually underrated, which are significant in boosting reaction activity. In this work, Ba single atoms were in situ prepared in the Co−Ba/Y 2 O 3 catalyst with crystallized BaCO 3 as the precursor under the ammonia decomposition reaction condition. The optimized Co−Ba/Y 2 O 3 catalyst achieves extremely high H 2 production rate of 138.3 mmolH 2 ⋅ g cat −1 ⋅ min −1 at very low temperature (500 °C, GHSV=840,000 mL ⋅ g −1 ⋅ h −1 ) and Co−Ba/Y 2 O 3 exhibits excellent durability during the 350 h test, which realizes the highest activity among all non‐noble catalysts, and reaches or even exceeds numerous reported Ru‐based catalysts. Both Y 2 O 3 and Co demonstrate positive interactions with Ba, which significantly facilitates the dispersion of Ba species at high temperatures (≥600 °C). Ba single atoms significantly enhance the charge density of Co and form additionally active Co−O−Ba−Y 2 O 3 interfacial sites, which alleviates hydrogen poisoning and decreases the reaction barrier of the N−H bond activation of *NH. The exploration of atomically dispersed promoters is groundbreaking in heterogeneous catalysis, which opens up a whole new domain of catalytic material.