Structure/Property-Activity: Green Catalysts


X-ray absorption spectroscopy (XAS) is a central technique in our quest for structure-activity relationships in water splitting. We further explored the terra incognita of highly active catalysts with both unknown motifs and completely amorphous structures. We established a comprehensive top-down & bottom-up approach that combined ex situ XAS and PDF with in situ formation monitoring of such catalysts. Our first target was a commercialized - yet structurally unknown – disordered Co-OER catalyst with oxidized dppe ligands. Its newly unraveled motif bears stunning analogy to bio-inspired systems and holds the key to high materials’ resilience (Matter 2019, 1, 1354).


Matter 2019, 1, 1354

Along these lines, we designed Zn/Sb-polyoxotungstates with excellent activity in alcohol oxidation. They underwent dynamic transformations to generate a widely recyclable and efficient true catalyst with highly disordered features. RMC-EXAFS fitting of this disordered Sb-deprived active species revealed its key structural features and underscored the power of XAS in identifying the operational changes of molecular catalysts (Dalton Trans. 2020, 49, 2468).


Chem. Eur. J. 2018, 24, 18242

In our systematic studies of Co-oxide catalysts, we demonstrated the crucial influence of detailed optimization of empirical synthesis parameter to hit the “sweet spots” of property-activity relationships.  The vast empirical parameter space to be screened for getting the most out of a given catalyst production was investigated representatively, applying microwave-hydrothermal synthesis on Co-spinel OERs (Front. Chem. 2020, 8, 473; ACS Omega 2019, 4, 15444). We currently explore the origins and influential order/disorder transitions of highly active Co-precipitates as effortless photocatalytic OER archetypes (in preparation).

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