As a promising porous material for CO2adsorption and storage, elastic layer-structured metal-organic framework-11 (ELM-11) has attracted significant attention owing to its distinct gate-opening phenomenon. There is a sharp increase in CO2uptake once reaching the gate-opening threshold pressure. To better understand this gate-opening mechanism, we investigated its transition process from the perspective of CO2dynamics and its interaction with the framework via variable-temperature13C solid-state nuclear magnetic resonance spectroscopy.Our findings revealed that during the gate-opening process, CO2is initially strongly adsorbed at one site when the gate only slightly opens,while two distinct types of CO2molecules exist when the gate fully opens.11B,13C, and19F magic-angle spinning NMR, in conjunction with in-situ XANES experiments, were also conducted to probethe location of adsorption sites.
Read full abstract