Catalysts consisting of isolated metal atoms on oxide supports have attracted wide attention because they offer new properties, but their active structures remain largely unknown because the metals are bonded at various, heterogeneous surface sites. Using computational electronic structure methods, we have predicted how to differentiate among MgO surface sites for iridium bonding, and demonstrated their contrasting structures and catalytic properties. MgO-supported single site iridium catalysts are modeled as (MgO)16IrL2 or (MgO)25IrL2 (L=CO or C2H4) for the MgO(100) surface and (MgO)20IrL2 for the MgO(110) surface. The structures and frequencies were calculated at the level of density functional theory with the ωB97X-D functional. The calculated results are in good agreement with experiments. The lowest-energy structures have various oxidation and spin states. The results demonstrate the complexity of oxide-supported single-site catalysts.

Computational study of single-site catalysts: MgO-supported iridium complexes

255th National Meeting (2018)

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