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

Abstract

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.

Keywords

ammonia synthesis / associative route / catalyst design / dissociative route / reaction mechanisms

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