Recent advancement of non-noble metal catalysts for hydrogen production by NH₃ decomposition

Paradigm transition towards green, clean and sustainable energy sources to reduce the global carbon footprint propelling the current energy market towards hydrogen economy due to the much reliable, carbon neutral and near zero emission properties though safe transportation and storage of hydrogen is a big challenge. Owing to its remarkable hydrogen content, easy storage and safe handling, NH₃ is the most suitable hydrogen carrier. Considering the energy potential of NH₃, this review, focus on the thermocatalytic decomposition of NH₃ for CO_x free production of H₂ on non-noble metal catalysts. Taking cost effectivity and scalability into account, recent development in design of inexpensive catalysts with metal components having less global warming potential are covered. A comprehensive survey and comparative assessment of recent (particularly post 2014) Co, Ni, Fe, Mo, metal carbides, imides, bimetallic and multimetallic catalysts with established benchmark catalysts is presented here. Effect of various promoters and supports on electronic properties, textural properties, reducibility and surface characteristics of catalyst is extensively reviewed. Mutual bimetallic synergism, novel synthetic approaches and reaction mechanism is also highlighted considering their role in successful execution of sustainable ammonia decomposition. A brief description of deactivation challenge of catalysts and measure taken to counter it is also given. Special emphasis is given to the catalysts which have potential of decomposition of ammonia at low temperature (<450 °C). Finally, summary and scope along with brief economic evaluation is presented targeting further development in large-scale production of H₂ from NH₃.