Over the past decades, polyoxometalates (POMs) have been studied extensively and have triggered a lot of attention in homogeneous catalysis due to their structural tunability and stability towards oxidative decomposition. Similar to POMs, polythiometalates (PTMs) have been known for decades, however, until very recently the main interest had focused on a purely synthetic point of view with respect to structural and supramolecular chemistry. This was mainly fuelled by the fact that PTMs are seen as zero-dimensional analogs to common MoS₂ and WS₂ nanostructures.

Recently, POMs and PTMs have been identified as promising candidates for water oxidation and water reduction catalysis. But the biggest challenge they face is that they suffer from quick deactivation due to degradation and self-aggregation under operational conditions.

In this project, we are wiring all-inorganic molecular oxide/sulfide clusters (POMs and PTMs) onto the surface of functional UV/visible-light active substrates with the ultimate aim to establish them as a platform for heterogeneous photocatalysis. These hybrids will further serve as model systems for fundamental studies to evaluate substrate effects on the stability, structure, and electronic properties of both components as well as on interfacial charge/heat transfer dynamics and catalytic steps.

Funding/Awards:

Austrian Science Fund (FWF) Stand-Alone Project P32801 (2020-2024, 378KEuro, PI: Alexey Cherevan)

Christiane Hörbiger Preis

​Collaborations involved:

Prof. Carsten Streb, Johannes Gutenberg University Mainz, Germany

Prof. Annette Rompel, University of Vienna, Austria

Publications:

We have started this journey with a dedicated analysis of the existing literature on POM heterogenization, which led us to write the first review , opens an external URL in a new windowthat summarized recent ground-breaking developments in the materials chemistry of supported polyoxometalates and established links between a molecular-level understanding of POM-support interactions and macroscopic effects including new or optimized reactivity, improved stability, and added functions. This review was published open-access in Advanced Science.

​The first experimental work , opens an external URL in a new windowon the topic appeared in ACS Catalysis. Here, we for the first time demonstrate the immobilization of an all-inorganic thiomolybdate [Mo₃S₁₃]^2- cluster on various metal oxide surfaces and investigate its function as a co-catalyst for photocatalytic hydrogen evolution reaction. We show that the attachment of the cluster on TiO₂ is strong and irreversible and that it follows monolayer adsorption, whereas the surface coverage is directly proportional to the cluster loadings.

Parallel to this, our first publication , opens an external URL in a new windowrelated to POM immobilization came out in ACS Materials Au. Here, we show anchoring of a molecular all-inorganic [Co^IIICo^II(H₂O)W₁₁O₃₉]^7– Keggin-type polyoxometalate onto a model inorganic surface, employing a 3-aminopropyltriethoxysilane (APTES) linker to form a novel heterogeneous photosystem for light-driven water oxidation.

We are currently working on expanding this strategy to novel supports and novel clusters.