Subsurface A-site vacancy activates lattice oxygen in perovskite ferrites for methane anaerobic oxidation to syngas

Tuning the oxygen activity in perovskite oxides (ABO 3 ) is promising to surmount the trade-off between activity and selectivity in redox reactions. However, this remains challenging due to the limited understanding in its activation mechanism. Herein, we propose the discovery that generating subsur...

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Published in:Nature communications 2024-06, Vol.15 (1), p.5422-11, Article 5422
Main Authors: He, Jiahui, Wang, Tengjiao, Bi, Xueqian, Tian, Yubo, Huang, Chuande, Xu, Weibin, Hu, Yue, Wang, Zhen, Jiang, Bo, Gao, Yuming, Zhu, Yanyan, Wang, Xiaodong
Format: Article
Language:English
Subjects:
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Catalysts
Cations
Electron density
Electron states
Ferrites
Humanities and Social Sciences
Hydrogen bonds
Lanthanum compounds
Lattice vacancies
Methane
multidisciplinary
Oxidation
Oxygen
Perovskites
Redox reactions
Science
Science (multidisciplinary)
Synthesis gas
Tradeoffs
Tuning
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Summary:Tuning the oxygen activity in perovskite oxides (ABO 3 ) is promising to surmount the trade-off between activity and selectivity in redox reactions. However, this remains challenging due to the limited understanding in its activation mechanism. Herein, we propose the discovery that generating subsurface A-site cation (La sub. ) vacancy beneath surface Fe-O layer greatly improved the oxygen activity in LaFeO 3 , rendering enhanced methane conversion that is 2.9-fold higher than stoichiometric LaFeO 3 while maintaining high syngas selectivity of 98% in anaerobic oxidation. Experimental and theoretical studies reveal that absence of La sub. -O interaction lowered the electron density over oxygen and improved the oxygen mobility, which reduced the barrier for C-H bond cleavage and promoted the oxidation of C-atom, substantially boosting methane-to-syngas conversion. This discovery highlights the importance of A-site cations in modulating electronic state of oxygen, which is fundamentally different from the traditional scheme that mainly credits the redox activity to B-site cations and can pave a new avenue for designing prospective redox catalysts. Tuning the oxygen activity in perovskite oxides (ABO 3 ) holds great potential for overcoming the trade-off between activity and selectivity in redox reactions. This paper highlights how A-site cations influence the electronic state of oxygen and how subsurface A-site vacancies enhance oxygen activity for improved methane conversion.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-024-49776-y