Selective ligand removal to improve accessibility of active sites in hierarchical MOFs for heterogeneous photocatalysis

Shaghayegh Naghdi (1) , Alexey Cherevan , Ariane Giesriegl , Rémy Guillet-Nicolas (2) , Santu Biswas (3) , Tushar Gupta (1) , Jia Wang (1) , Thomas Haunold (1) , Bernhard Christian Bayer (1) , Günther Rupprechter (1) , Maytal Caspary Toroker (3) , Freddy Kleitz (4) , Dominik Eder (1)

1 TU Wien - Vienna University of Technology = Technische Universität Wien
2 LCS - Laboratoire catalyse et spectrochimie
3 Technion - Israel Institute of Technology [Haifa]
4 Universität Wien = University of Vienna

Abstract Metal-organic frameworks (MOFs) are commended as photocatalysts for H 2 evolution and CO 2 reduction as they combine light-harvesting and catalytic functions with excellent reactant adsorption capabilities. For dynamic processes in liquid phase, the accessibility of active sites becomes a critical parameter as reactant diffusion is limited by the inherently small micropores. Our strategy is to introduce additional mesopores by selectively removing one ligand in mixed-ligand MOFs via thermolysis. Here we report photoactive MOFs of the MIL-125-Ti family with two distinct mesopore architectures resembling either large cavities or branching fractures. The ligand removal is highly selective and follows a 2-step process tunable by temperature and time. The introduction of mesopores and the associated formation of new active sites have improved the HER rates of the MOFs by up to 500%. We envision that this strategy will allow the purposeful engineering of hierarchical MOFs and advance their applicability in environmental and energy technologies.

Domaines: Matériaux; Catalyse

Shaghayegh Naghdi, Alexey Cherevan, Ariane Giesriegl, Rémy Guillet-Nicolas, Santu Biswas, et al.. Selective ligand removal to improve accessibility of active sites in hierarchical MOFs for heterogeneous photocatalysis. Nature Communications, 2022, 13 (1), pp.282. ⟨10.1038/s41467-021-27775-7⟩. ⟨hal-03878561⟩