Operando Identification of the Active Phase in Sr‐Promoted Lanthanum Cobaltite Perovskite‐Derived Catalysts for Ammonia Decomposition

ABSTRACT Storing energy in molecular form, particularly hydrogen in carbon‐free carriers such as ammonia, is considered a key strategy for future energy systems. The release of hydrogen via ammonia decomposition is a critical step in this context that requires scalable and economically viable catalysts. In this work, spray‐flame synthesis (SFS) was employed to prepare La 1– x Sr x CoO 3− δ (0≤ x ≤ 1) nanoparticles (≈ 10 nm), which serve as precursors for SrO‐promoted Co/La 2 O 3 catalysts prepared by exsolution. ESR, operando XRD, and ambient pressure photoelectron spectroscopy (APXPS) provide insights into dynamic interfacial restructuring of the catalysts under the harsh ammonia decomposition conditions. The catalysts contain 25 wt% Co and achieve a maximum hydrogen productivity of 108 ·g Co −1 ·min −1 at 500°C for the La 0.75 Sr 0.25 CoO 3− δ ‐derived material. The coverage of La 2 O 3 with SrO/Sr─OH species under reaction conditions inhibits the migration of La‐based species, which block active Co sites in the absence of the promoter. An excess of Sr, however, promotes the growth of Co particles and reduces the exposed Co surface area. Beyond its structural role, operando APXPS reveals that SrO also influences reaction kinetics by facilitating NH x decomposition and weakening the binding strength of nitrogen, which is consistent with an electrostatic effect of SrO.

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Journal
Angewandte Chemie International Edition
Published
2026-10-27
DOI
https://doi.org/10.1002/anie.1879497
Primary Topic
Ammonia Synthesis and Nitrogen Reduction
Type
article
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article

Operando Identification of the Active Phase in Sr‐Promoted Lanthanum Cobaltite Perovskite‐Derived Catalysts for Ammonia Decomposition

Annette Trunschke, Wiebke Riedel, Konstantinos Kappis, Kassiogé Dembélé et al.
4 links
Angewandte Chemie International Edition
Ammonia Synthesis and Nitrogen Reduction
article

Operando Identification of the Active Phase in Sr‐Promoted Lanthanum Cobaltite Perovskite‐Derived Catalysts for Ammonia Decomposition

Annette Trunschke, Wiebke Riedel, Konstantinos Kappis, Kassiogé Dembélé, Gregor Koch, Thomas Lunkenbein, Mattia Scardamaglia, Detre Teschner, Liseth Duarte‐Correa, Zohreh Asadi, Anh Binh Ngo, Frank Girgsdies, Olaf Timpe, Mino Borrelli, Barış Alkan, Thomas Risse, Axel Knop‐Gericke
article en

Abstract

ABSTRACT Storing energy in molecular form, particularly hydrogen in carbon‐free carriers such as ammonia, is considered a key strategy for future energy systems. The release of hydrogen via ammonia decomposition is a critical step in this context that requires scalable and economically viable catalysts. In this work, spray‐flame synthesis (SFS) was employed to prepare La 1– x Sr x CoO 3− δ (0≤ x ≤ 1) nanoparticles (≈ 10 nm), which serve as precursors for SrO‐promoted Co/La 2 O 3 catalysts prepared by exsolution. ESR, operando XRD, and ambient pressure photoelectron spectroscopy (APXPS) provide insights into dynamic interfacial restructuring of the catalysts under the harsh ammonia decomposition conditions. The catalysts contain 25 wt% Co and achieve a maximum hydrogen productivity of 108 ·g Co −1 ·min −1 at 500°C for the La 0.75 Sr 0.25 CoO 3− δ ‐derived material. The coverage of La 2 O 3 with SrO/Sr─OH species under reaction conditions inhibits the migration of La‐based species, which block active Co sites in the absence of the promoter. An excess of Sr, however, promotes the growth of Co particles and reduces the exposed Co surface area. Beyond its structural role, operando APXPS reveals that SrO also influences reaction kinetics by facilitating NH x decomposition and weakening the binding strength of nitrogen, which is consistent with an electrostatic effect of SrO.

Angewandte Chemie International Edition
Lund University (SE), Fritz Haber Institute of the Max Planck Society (DE), Max Planck Institute for Chemical Energy Conversion (DE), MAX IV Laboratory (SE), University of Bayreuth (DE), Freie Universität Berlin (DE)
European Commission, VINNOVA, Svenska Forskningsrådet Formas, Vetenskapsrådet, Helmholtz-Zentrum Berlin für Materialien und Energie
Affordable and clean energy
Openalex Percentile: Top 37%
Ammonia Synthesis and Nitrogen Reduction
DOIOpen Access PDFOpenAlex
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