Electronic parameters in cobalt-based perovskite-type oxides as descriptors for chemocatalytic reactions

Johannes Simböck; M Ghiasi; Simon Schönebaum; Ulrich Simon; Frank M F de Groot; Regina Palkovits

doi:10.1038/s41467-020-14305-0

Electronic parameters in cobalt-based perovskite-type oxides as descriptors for chemocatalytic reactions

Nat Commun. 2020 Jan 31;11(1):652. doi: 10.1038/s41467-020-14305-0.

Authors

Johannes Simböck^{1

2}, M Ghiasi³, Simon Schönebaum^{2

4}, Ulrich Simon^{2

4}, Frank M F de Groot³, Regina Palkovits^{5

6}

Affiliations

¹ Chair of Heterogeneous Catalysis and Chemical Technology, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany.
² Center for Automotive Catalytic Systems Aachen, RWTH Aachen University, Aachen, 52074, Germany.
³ Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, Netherlands.
⁴ Institute of Inorganic Chemistry, RWTH Aachen University, 52074, Aachen, Germany.
⁵ Chair of Heterogeneous Catalysis and Chemical Technology, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany. palkovits@itmc.rwth-aachen.de.
⁶ Center for Automotive Catalytic Systems Aachen, RWTH Aachen University, Aachen, 52074, Germany. palkovits@itmc.rwth-aachen.de.

Abstract

Perovskite-type transition metal (TM) oxides are effective catalysts in oxidation and decomposition reactions. Yet, the effect of compositional variation on catalytic efficacy is not well understood. The present analysis of electronic characteristics of B-site substituted LaCoO₃ derivatives via in situ X-ray absorption spectroscopy (XAS) establishes correlations of electronic parameters with reaction rates: TM t_2g and e_g orbital occupancy yield volcano-type or non-linear correlations with NO oxidation, CO oxidation and N₂O decomposition rates. Covalent O 2p-TM 3d interaction, in ultra-high vacuum, is a linear descriptor for reaction rates in NO oxidation and CO oxidation, and for N₂O decomposition rates in O₂ presence. Covalency crucially determines the ability of the catalytically active sites to interact with surface species during the kinetically relevant step of the reaction. The nature of the kinetically relevant step and of surface species involved lead to the vast effect of XAS measurement conditions on the validity of correlations.

Abstract

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