Deciphering Catalytic Reaction Mechanisms for Low‐Temperature Ammonia Synthesis: Mechanism‐Guided Rational Design of Active Sites

Ammonia serves as a dual‐purpose nitrogen and hydrogen carrier, essential for global food security and the ongoing renewable energy transition. The century‐old industrial Haber‐Bosch process, however, is limited by considerable energy consumption and massive carbon emissions, necessitating efficient catalysts for low‐temperature ammonia synthesis. Despite recent progress in diverse catalytic systems, including electrides, nitrides, hydrides, and engineered transition‐metal sites, differences in active‐site architecture give rise to distinct reaction routes, and a unified mechanistic framework remains absent. This review systematically summarizes recently developed catalytic systems based on a mechanism‐driven classification covering dissociative, hydrogen‐assisted, and associative routes, with emphasis on structure–activity relationships and mechanistic insights revealed through advanced characterization techniques. By critically evaluating state‐of‐the‐art catalysts, this review establishes strategic design principles to guide the rational development of next‐generation ammonia synthesis catalysts.