Amorphous LiN<sub><i>x</i></sub>H<sub><i>y</i></sub> Boosts Low-Temperature Ammonia Decomposition over the Co/MgO Catalyst
Peijie Han, Liang Xu, Hui Ying Yang, Ning Yan
Abstract
Catalytic ammonia decomposition facilitated by lithium species such as LiNH 2 and Li 2 NH has attracted increasing attention alongside growing interest in hydrogen energy. However, the active site requirements and reaction mechanisms of Li-assisted catalysts remain controversial. In this study, we demonstrate that the incorporation of lithium species significantly enhances the ammonia decomposition rate of a cobalt-based catalyst by up to 5-fold at 623 K and achieves almost the best low-temperature activity among reported Ru-free catalysts. Structural characterization and density functional theory (DFT) calculations suggest that Li sites with vacancies, located at the interface between the amorphous LiN x H y species and the Co surface, serve as the active sites for ammonia decomposition. For the N–H bond scission step during ammonia cracking, Li atoms located at this vacancy site exhibit a displacement of 1.7 Å per Li atom under a direct weak interaction with the Co surface to construct the energy-favorable geometry.