Lithium Imide Synergy with 3d Transition‐Metal Nitrides Leading to Unprecedented Catalytic Activities for Ammonia Decomposition

Abstract Alkali metals have been widely employed as catalyst promoters; however, the promoting mechanism remains essentially unclear. Li, when in the imide form, is shown to synergize with 3d transition metals or their nitrides TM(N) spreading from Ti to Cu, leading to universal and unprecedentedly high catalytic activities in NH 3 decomposition, among which Li 2 NHMnN has an activity superior to that of the highly active Ru/carbon nanotube catalyst. The catalysis is fulfilled via the two‐step cycle comprising: 1) the reaction of Li 2 NH and 3d TM(N) to form ternary nitride of LiTMN and H 2 , and 2) the ammoniation of LiTMN to Li 2 NH, TM(N) and N 2 resulting in the neat reaction of 2 NH 3 ⇌N 2 +3 H 2 . Li 2 NH, as an NH 3 transmitting agent, favors the formation of higher N‐content intermediate (LiTMN), where Li executes inductive effect to stabilize the TMN bonding and thus alters the reaction energetics.