[Zurück]

S. Naghdi, J. Wang, C. Hannecart, G.M. Haselmann, A. Cherevan, D. Eder:
"Improve accessibility of active sites in hierarchical MOFs for heterogeneous photocatalysis";
Poster: 1st International Gas Adsorption Summer School, Spetses, Greece; 09.09.2019 - 13.09.2019.

Metal-Organic frameworks (MOFs) have recently gained interest as an innovative class of functional materials owing to their catalytically active oxo-metal clusters, functional organic linkers, easily tunable photophysical/chemical properties and a large surface area along with well-ordered microporous structure1. MOFs have also shown great potential as photocatalysts (e.g. hydrogen evolution and CO2 reduction2) as they can combine light-harvesting and catalytic functions with an excellent reactant adsorption capability. In dynamic processes and especially in liquid phase catalysis, the accessibility of active sites becomes a critical parameter as the reactant diffusion is often limited by the inherently small micropores of MOFs.
One promising strategy to overcome this challenge involves selective ligand removal of mixed ligand-MOFs, which introduces larger mesopores and thus facilitates reactant diffusion to the active sites3. In this work, we have synthesized a series of novel Ti-based mixed ligand MOFs via solvothermal reaction and investigated the selective ligand removal induced by heat and solvent. We then evaluated these MOFs with respect to their photocatalytic activity and conversion efficiency for both, H2 formation and CO2 reduction.
We were able to confirm the selective ligand removal and the introduction of mesopores without affecting the overall crystal structure by a range of techniques, including Raman spectroscopy, IR spectroscopy, 1HNMR, N2-Physisorption, X-Ray photo spectroscopy (XPS) and TEM microscopy. We are currently testing these hierarchically porous MOFs for impregnation with transition metal/metal oxide nanoclusters used as co-catalyst for the respective photocatalytic reaction.