Ammonia synthesis and decomposition mediated by hydrides, imides, and amides
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Muhammad Anis Aslam
Shanghai Key Laboratory of Hydrogen Science & Centre of Hydrogen Science, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
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Sajad Hussain
Department of Environmental Sciences, Comsats University Islamabad, Vehari Campus, Vehari 61100, Pakistan
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Ismat Ullah Khan
Department of Chemistry, Government Post Graduate College (GPGC), Lakki Marwat 28420, Pakistan
Abstract
Ammonia is used for global fertilizer production and is increasingly viewed as a viable carrier for renewable hydrogen and long-duration energy storage. Realizing this potential requires catalysts and process architectures that enable both N₂-to-NH₃ synthesis and NH₃-to-H₂ decomposition at substantially reduced temperature and pressure. This review surveys recent advances in which alkali- and alkaline-earth metal hydrides, amides, and imides act as dynamic redox and hydrogen/nitrogen-transfer media, undergoing reversible interconversion with N₂, H₂, and NH₃. We summarize thermocatalytic systems where hydridic H⁻ and electron-rich lattices promote N₂ activation, heterolytic H₂ cleavage, and N–H bond formation, including composite catalysts that exploit cooperative interfaces with transition metals and complex or mixed-anion hydrides that relax constraints imposed by conventional metal-only surfaces. We also discuss photo-assisted routes that leverage defect-stabilized charge carriers in hydrides to drive nitrogen conversion under illumination, and chemical-looping strategies that decouple nitrogen fixation from hydrogenation (or hydrogen release) to tune thermodynamics and mitigate competitive adsorption. Across these platforms, recurring motifs include lattice-mediated hydride/proton shuttling, interfacial electron donation, and reversible nitride–imide–amide formation that can be engineered to balance activity, selectivity, and stability. Finally, we outline key barriers to practical deployment, air/moisture sensitivity, carrier volatility, phase segregation, and limited operando understanding and highlight design priorities for stabilizing reactive phases and integrating reactors compatible with renewable heat, photons, or electricity, thereby enabling scalable and decentralized ammonia and hydrogen technologies.
Copyright (c) 2025 Muhammad Anis Aslam, Sajad Hussain, Ismat Ullah Khan
This work is licensed under a Creative Commons Attribution 4.0 International License.
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