MOF-electrocatalyst reconstruction-modulation and active site second coordination sphere optimization.

• Applicants: Professor Dr. Aliaksandr Bandarenka; Professor Dr. Roland A. Fischer
• Subject Area: Solid State and Surface Chemistry, Material Synthesis ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 563951947

Carboxylate MOFs featuring metal-oxo nodes, in particular 1D chains of edge and/or corner sharing MO6-Octahedra, which are interconnected by carboxylate linkers and showing metal ion bridging hydroxy groups are candidates for deriving highly active, even "superactive" OER (and ORR) catalysts for electrochemical water splitting in alkaline medium. However, controversy persists about the role and functionality of the pristine MOFs in comparison to their gradually reorganized derivatives and their fully transformed metal oxo/hydroxides as the actual materials, providing the catalytically highly active metal ion sites. The nature of the MOF-based/derived OER catalyst is dynamic and evolves during electrode fabrication, activation, and electrocatalytic testing in operando. These dynamics and reconstruction processes suggest unique optimization of the microstructure of the catalytic active sites, including the effects of mixed metal solid solution and the effects of additives to the electrolyte such as extra carboxylate linkers, which either directly modulate the active site or the proximity of the active site at the interface to the electrolyte. We call our approach: "MOF-electrocatalyst reconstruction- modulation and active site second coordination sphere optimization". The developed methodology and obtained insight may also hold for other types of MOFs or coordination network compounds (with or without persistent porosity) that feature other linkers than carboxylates (e.g. azolates, phosponates etc.) and are employed as electrocatalysts for OER and for other reactions under similar conditions.

• DFG Programme: Research Grants