Catalyst design for ammonia decomposition: an overview

Ammonia serves as a viable medium for hydrogen storage owing to its significant hydrogen content and elevated energy density, and the absence of carbon dioxide emissions during ammonia-to-hydrogen production has inspired more research on ammonia decomposition. Despite growing interest, a significant gap persists between the depth of existing studies and the practical approach to on-the-spot hydrogen generation using ammonia decomposition. The creation of effective and accessible catalysts to feed ammonia decomposition is a critical step in addressing this daunting challenge. This paper systematically summarizes four key catalyst design strategies, including size effect, alkalinity modulation, metal–support interactions, and alloying, informed by experimental and theoretical investigations into ammonia decomposition. Each strategy's underlying mechanism for enhancing ammonia decomposition is elucidated in detail. Moreover, the paper categorizes catalysts employed in existing ammonia decomposition reactors to guide future catalyst development. The influence of diverse energy sources and reactor configurations on catalyst performance is also discussed to provide a comprehensive framework for advancing ammonia decomposition catalyst research.