Porous Metal–Organic Framework CUK-1 for Adsorption Heat Allocation toward Green Applications of Natural Refrigerant Water

The development of new water adsorbents that are hydrothermally stable and can operate more efficiently than existing materials is essential for the advancement of water adsorption-driven chillers. Most of the existing benchmark materials and related systems in this field suffer from clear limitations that must be overcome to meet global requirements for sustainable and green energy production and utilization. Here, we report the energy-efficient water sorption properties of three isostructural metal-organic frameworks (MOFs) based on the simple ligand pyridine-2,4-dicarboxylate, named M-CUK-1 [M 3 (μ 3 -OH) 2 (2,4-pdc) 2 ] (where M = Co 2+ , Ni 2+ , or Mg 2+ ). The highly hydrothermally stable CUK-1 series feature step-like water adsorption isotherms, relatively high H 2 O sorption capacities between P / P 0 = 0.10-0.25, stable cycling, facile regeneration, and, most importantly, benchmark coefficient of performance values for cooling and heating at a low driving temperature. Furthermore, these MOFs are prepared under green hydrothermal conditions in aqueous solutions. Our joint experimental-computational approach revealed that M-CUK-1 integrates several optimal features, resulting in promising materials as advanced water adsorbents for adsorption-driven cooling and heating applications.