MOFs and MOCHAs

Metal-Organic Frameworks (MOFs)

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 structure. MOFs have also shown great potential as photocatalysts (e.g. hydrogen evolution and CO2 reduction) 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 the synthesis of mixed-ligand MOFs, followed by selective ligand removal (e.g. via selective oxidation, thermal degradation or dissolution) to design novel hierarchical microporous-mesoporous MOFs that facilitate reactant diffusion as well as induce uncoordinated centres as potential catalytic sites. These are truly novel materials that combine hierarchical porosity with the multifunctionality of the inorganic-organic hybrid system. Key to their study is an unambiguous characterization of surface area and pore characteristics (width, shape, connectivity, distribution), for which the standard models in physisorption studies are often not applicable.

This strategy also introduces additional mesopores by selectively removing one ligand in mixed-ligand MOFs via thermolysis. The impact of selective ligand removal on heat-treated MOFs affects the adsorption of contaminant in water/wastewater as well. The relationship between the most important factors, such as contact duration.

A series of mixed-ligand MOFs are investigated and the selective ligand removal upon thermolysis is characterized with a range of the state-of-the-art techniques.

[Translate to English:] electron transfer

© Shaghayegh Naghdi

Proposed mechanism for photocatalytic HER on MOFs after selective ligand removal. Atom colour: Ti (blue), O (red), C (brown), H (white). (see adsorbed methoxy groups on the left-hand side as new active sites)

Metal-Organic Chalcogenolate Assemblies (MOCHAs)

MOCHAs are new and exciting class of organic-inorganic hybrid materials. In our group we design and synthesize MOCHAs with different metal centers and organic ligands and explore their electrocatalytic as well as photocatalytic properties.

Chemical Structure of Various MOCHAs

© AG Eder

Chemical Structure of Various MOCHAs

Chemical Structure of Various MOCHAs

© AG Eder

Chemical Structure of Various MOCHAs