Atomically dispersed Ce species adjacent to Ni nanoparticles as hydrogen scavengers for efficient catalytic ammonia decomposition

CeO2 serves as an essential support or promoter for catalysts in ammonia decomposition, especially those based on Ni, yet its direct contribution to promoting NH3 activation and H2 desorption has rarely been understood. Here, we prepare a Ni-Ce-Al trinary catalyst with high-loading (66.5 wt%) Ni nanoparticles. Connected by the Al2O3 framework, these Ni nanoparticles are surrounded by abundant atomically dispersed Ce species consisting of Ce single atoms and clusters. The activity-stability trade-off induced by intrinsic Ni sintering on the CeO2 support is overcome, achieving a high H2 production rate of 324.0 mmol gcat−1 min−1 at 600 °C. The promoting effect of CeO2 has been elucidated, originating from the alleviation of hydrogen poisoning. Atomically dispersed Ce species with high hydrogen affinity serve as scavengers for adsorbed H atoms (H*). The strong tendency to form Ce3+‒OH groups facilitates the migration of H* from Ni nanoparticles to the oxide, releasing poisoned Ni sites and promoting NH3 activation. Ammonia can store clean hydrogen, but nickel catalysts often lose activity during release. This study shows atomically dispersed cerium species help clear hydrogen from nickel sites, boosting ammonia decomposition.