In situ Nanoscale Infrared Spectroscopy of Water Adsorption on Nanoislands of Surface-Anchored Metal-Organic Frameworks

Despite technological advancements, probing gas-solid interfaces at the nanoscale is still a formidable challenge. New nano-spectroscopic methods are needed to understand the guest-host interactions of functional materials during gas sorption, separation, and conversion. Herein, we introduce in situ Photoinduced Force Microscopy (PiFM) to evidence site-specific interaction between Metal-Organic Frameworks (MOFs) and water. To this end, we developed amphiphilic Surface-anchored MOF (SURMOF) model systems using self-assembly for the side-by-side hetero-growth of nanodomains of hydrophilic HKUST-1 and hydrophobic ZIF-8. PiFM was used to probe local uptake kinetics and to show D2O sorption isotherms on (defective) HKUST-1 paddlewheels. By monitoring defect vibrations, we visualized in real-time the saturation of existing defects and the creation of D2O-induced defects. This work shows the potential of in situ PiFM to unravel gas sorption mechanisms and map active sites on functional (MOF) materials.

Automated summary

Despite technological advancements, probing gas-solid interfaces at the nanoscale remains a challenging task. This study introduces the in situ Photoinduced Force Microscopy (PiFM) to investigate the interactions between Metal-Organic Frameworks (MOFs) and water. The use of PiFM in this research has shown potential in unraveling gas sorption mechanisms and mapping active sites on functional materials like MOFs.