Recent progress in the decomposition of ammonia as potential hydrogen-carrier by green technologies

Abstract

To meet the global carbon neutrality target set by the United Nations, finding alternative and cost-effective energy sources has become prominent while enhancing energy conversion methods’ efficiency. The versatile applications of hydrogen (H₂) as an energy vector have been highly valued over the past decades due to its significantly lower greenhouse gas emissions compared to conventional fossil fuels. However, challenges related to H2 generation and storage for portable applications have increasingly called attention to ammonia (NH3) decomposition as an effective method of on-site hydrogen production due to its characteristic high hydrogen content, high energy density, and affordability. This review highlights recent developments in green decomposition techniques of ammonia, including catalytic membrane reactors, microchannel reactors, thermochemical processes, non-thermal plasma, solar-driven decomposition, and electrolysis, with a focus on the latest developments in new methods and materials (catalysts, electrodes, and sorbents) employed in these processes. Moreover, technical challenges and recommendations are discussed to assess the future potential of ammonia in the energy sector. The role of machine learning and artificial intelligence in ammonia decomposition is also emphasized, as these tools open up ways of simulating reaction mechanisms for the exploration of a new generation of high-performance catalysts and reduce trial-and-error approaches.