Structure-Function Interplay in Metal Organic Framework Systems for the Catalytic CO2 Photoreduction

Abstract

As the quest for sustainable energy resources remains a global challenge, it becomes crucial to design potent materials that would concurrently mitigate the excessive CO2 emissions while producing value-added feedstocks. Within this context, metal organic frameworks (MOFs) emerged as a diverse class of porous crystalline materials that deemed to efficiently contribute to various stages of the CO2 cycle, from its capture to its conversion. More specifically, the rational choice of MOFs building blocks, along with the deep investment in their structural properties, can potentially enhance their optical and catalytic activities. In order to develop novel photocatalytic MOF systems, we systematically investigate the catalytic performance of a series of previously reported, yet unexplored MOF structures on one hand and a finely tuned MOF series on the other hand, both operating under light irradiation. In the former approach, three isostructural MOFs namely NbOFFIVE-1-Ni, AlFFIVE-1-Ni and FeFFIVE-1-Ni, known for their exceptional CO2 capture abilities from thin air, are tested as CO2 photo-reduction catalysts. The in-depth characterization of the studied MOFs before and after catalysis demonstrates the occurrence of in-situ structural changes yielding remarkable conversion rates. As for the second photocatalytic system, mixed-linker derivatives of UiO-66, a remarkably robust and extensively studied MOF topology, are synthesized by varying the amount of -COOH functionalities within the framework. These multivariate MOF samples are fully characterized in order to establish structural, morphological and physical trends. Post-synthetic metalation is also performed to incorporate potential active sites into this series of MTV-MOFs which are subsequently tested as potent photocatalysts. These separate, yet parallel studies highlight the role of structure-function interplay in MOF systems, thus widening the scope of MOF engineering strategies for a sustainable future.