A combined XAS/XES investigation of photochemically-driven water capture and release in azopyridine-appended metal-organic frameworks

Water scarcity is one of the key contemporary environmental issues. Metal Organic Frameworks (MOFs) have emerged as unique materials for atmospheric water harvesting even at very low relative humidity levels, with facile uptake and release kinetics. In order to rationally design improved water harvesting MOFs it is however critical to reach a detailed mechanistic, structural, and electronic understanding of the dynamic adsorption-desorption process. Here, we propose a combined in situ hard XAS/XES study to investigate the local structural and electronic modifications that occur during water adsorption and desorption in MOF systems appended with azopyridine molecules that undergo photochemically induced cis/trans transitions, which regulate the water uptake and release. We expect our results to unveil the stages of water capture by selected MOFs with unprecedented detail, thereby paving the way for the rational design of improved MOF water harvesting systems.