Metal-organic frameworks for NH₃ adsorption and separation

Ammonia (NH₃) is not only an air pollutant but also a versatile and favourable chemical with widespread applications in human life. As a key component of nitrogen fertilizers, it plays a crucial role in improving crop yields. Additionally, NH₃ serves as a hydrogen carrier and working fluid, contributing to the energy transition process. Given the diverse roles of NH₃ and the varying requirements for adsorbents across different application scenarios, the rational design and selection of adsorbent materials are paramount. Metal-organic frameworks (MOFs) have emerged as promising adsorbent candidates due to their highly tunable structure and functionality, which can precisely match the characteristics required for NH₃ adsorbents in multiple application scenarios. This review provides a comprehensive evaluation of NH₃ adsorbents and delves into the stability characterization of MOFs under NH₃ atmospheres and the underlying adsorption/degradation mechanisms. Additionally, we discuss the existing methods used to probe the host-guest interactions between MOFs and NH₃. Finally, this study systematically summarizes the latest advancements of MOFs as NH₃ adsorbents and classifies them according to the different requirements imposed by the varying roles of NH₃. This review provides theoretical support for the design of more efficient NH₃ adsorbents in the future.