Calcium Imide: A New Catalyst for Plasma‐Catalytic Ammonia Synthesis

ABSTRACT Plasma‐catalytic ammonia synthesis is an emerging alternative approach for the sustainable conversion of dinitrogen (N ₂ ) to ammonia (NH ₃ ) using renewable electricity. However, the development of efficient catalysts for plasma‐driven ammonia synthesis remains a formidable challenge. Herein, we report that calcium imide (CaNH) functions as an active, transition‐metal‐free catalyst for plasma‐driven ammonia synthesis. Under 25 W and 20 kHz dielectric barrier discharge (DBD) conditions, the ammonia synthesis rate over CaNH is approximately three times that of the blank test, representing a performance enhancement comparable to the widely studied benchmark Ni/Al ₂ O ₃ catalyst. Combined experimental and computational results reveal that the CaNH surface, with plasma‐generated coordinatively unsaturated calcium sites, plays a critical role in promoting the hydrogenation of N _x H _y species to generate NH ₃ rather than in the activation of N ₂ —thus redefining the rate‐determining step. This study unveils a new functionality of alkaline earth metal imides in plasma‐catalytic ammonia synthesis, thereby offering greater opportunities for the development of new materials and active catalysts. Furthermore, this work provides new insights into the catalytic mechanism of other catalysts for plasma‐catalytic ammonia synthesis.