Observing structural changes induced by gas adsorption in COF-300 with micro-Raman Spectroscopy

Abstract

Covalent Organic Frameworks (COFs) are a class of organic materials known for their nano and microporous structures. Their properties can be carefully tuned by selecting specific building blocks, which leads to many applications in catalysis, energy storage and gas separation. Specifically, many COFs have been explored for their use in capturing CO2 and separating it from other gases present in flue gas, like N2. Previous reports have already shown that COFs can be potential candidates for effective and selective gas adsorption. However, despite this potential, there aren’t many works discussing the mechanisms behind the adsorption processes and the possible active sites. In this work, COF-300 was chosen as the case study because it is a well-known material, and it has interesting features like pore interpenetration and flexibility of the framework. Although COF-300 is well studied, a Raman profile of this material hasn’t been explored yet. For that, we have designed an environmental cell, in which we can measure the Raman spectrum for a porous material while changing, the pressure and the gas injected inside the cell, observing the shifts and intensity changes on the Raman spectrum on different environmental conditions. We also compared the experimental spectrum to a DFT simulated spectrum for an assignment of COF-300 Raman bands.