Enhancing Gravimetric and Volumetric Ammonia Capacities of Metal-Organic Frameworks via Consecutive Post-Synthetic Modification

Ammonia is a promising energy vector that can store the high energy density of hydrogen. For this reason, numerous adsorbents have been investigated as ammonia storage materials, but ammonia adsorbents with a high gravimetric/volumetric ammonia capacity can be simultaneously regenerated in an energy-efficient manner remain underdeveloped, which hampers their practical implementation. Herein, we reported Ni_acryl_TMA (TMA = thiomallic acid), an acidic group functionalized metal-organic frameworks prepared via double post-synthetic modifications showing top-tier gravimetric ammonia capacity of 23.5 mmol g^-1 and the unprecedented ammonia storage density of 0.39g cm^-3 at 1 bar and 298 K with facile regeneration. The ammonia storage properties and adsorption mechanism were characterized by ammonia isotherm, NH₃-temperature-programmed desorption curves, NH₃ breakthrough curves, <i>in-situ</i> FT-IR, and DFT-calculation. Detailed synthesis and properties will be presented in the presentation.