Thread Content
Efficient methane conversion achieved through the activation of periclase lattice oxygen by subsurface La defects. Recently, a team led by Researcher Wang Xiaodong and Associate Researcher Huang Chuande from the Catalysis and New Materials Research Center (Group 1500) at the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, in collaboration with Professor Zhu Yanyan from Northwest University and Associate Professor Jiang Bo from Dalian University of Technology, has made new progress in the research on efficient and selective oxidation of methane using periclase catalysts. The lattice oxygen activity of metal oxides plays a crucial role in catalytic reactions that follow the Mars–van Krevelen mechanism. Precise control over lattice oxygen activity holds promise for overcoming the \"see-saw effect\" between activity and selectivity in redox reactions. Perovskite oxides (ABO3) have excellent structural stability, redox activity, and a tunable crystal structure, which has attracted the attention of researchers in redox reactions. Compared to the chemically inert A-site atoms, researchers generally attribute the excellent oxygen activity of perovskite structures to the transition metals at the B-site, considering the role of A-site atoms to be very limited; they believe that oxygen activity can only be adjusted indirectly by changing the crystal structure or modifying the valence state of the B-site atoms. For a long time, the potential role of A-site atoms in directly regulating oxygen activity has been overlooked, which has led to a limited understanding of the mechanisms underlying oxygen activity activation and made it difficult to achieve precise control over it. In this work, the research team found that reducing the La/Fe ratio (La0.97FeO3) or surface-restructuring LaFeO3 through redox treatment can both generate subsurface La (Lasub.) defects. Experimental and theoretical studies show that the absence of the subsurface Lasub.-O interaction can reduce the electron density of surface oxygen and increase its mobility, thereby lowering the activation energy barrier for CH4 from 1.88 eV to 1.03 eV. This improves the efficiency of methane conversion to syngas, increasing the syngas yield by 2.7 to 2.9 times while maintaining a high syngas selectivity of 96% to 98%. This work emphasizes the importance of the A-site atom in directly regulating oxygen activity, which is fundamentally different from traditional views and provides new insights for the design of redox catalysts. The team has been dedicated to the development of catalysts for the efficient conversion of low-carbon alkanes, and has made a series of advances (Energy Environ. Sci., 2019 ； ACS Catal., 2020 ； ACS Catal., 2020 ； ACS Catal., 2021 ； Nat. Commu., 2021 ； Nat. Catal., 2022 ； J. Am. Chem. Soc., 2022 ； Angew. Chem. Int. Ed. Engl., 2022 ； J. Am. Chem. Soc., 2023 ； J. Mater. Chem. A, 2023 ； Angew. Chem. Int. Ed. Engl., 2024). The relevant findings were published in Nature Communications under the title “Subsurface A-site vacancy activates lattice oxygen in perovskite ferrites for methane anaerobic oxidation to syngas”. The co-first authors of this article are He Jiahui, a master’s student trained jointly by Group 1503 of our institute and Northwestern University, and Wang Tengjiao, a master’s student from Dalian University of Technology. The above work was supported by the **National Natural Science Foundation of China**, the basic science research project on \"single-atom catalysis\" funded by the National Natural Science Foundation Committee, the Youth Promotion Association of the Chinese Academy of Sciences, and other funding programs.