A comprehensive review on hydrogen production via catalytic ammonia decomposition over Ni-based catalysts

Hydrogen (H₂) is recognized as a highly promising alternative to fossil fuels. When combusted, it provides the highest energy per unit mass and produces only water, making it an ideal fuel for the future. However, challenges persist in the manufacturing, storage and transportation of H₂. Ammonia (NH₃) has emerged as a promising H₂ carrier, effectively addressing many hurdles associated with H₂ transportation and storage. Nevertheless, the primary challenge in NH₃ decomposition lies in achieving complete conversion at low temperatures while utilizing cost-effective catalysts. This review article hiighlights recent advancements in NH₃ decomposition, focusing on key challenges that remain to be addressed. It explores developments in reaction thermodynamics and kinetics, analyzing whether nitrogen desorption or the breaking of the initial N–H bond primarily controls the reaction rate. The review also provides an in-depth examination of the latest innovations in Nickel-based catalysts and the mechanisms underlying NH₃ decomposition on these catalysts. Additionally, it discusses the influence of promoters and supports on catalytic performance. This comprehensive review serves as a valuable reference for researchers, policymakers, and industry experts involved in NH₃-based hydrogentransportation and storage technologies.