Engineering surface segregation of perovskite oxide through wet exsolution for CO catalytic oxidation

• Published in: Journal of hazardous materials 2022-08, Vol.436, p.129110-129110, Article 129110
• Main Authors: Li, Zhen, Wang, Xiyang, Li, Xinbo, Zeng, Minli, Redshaw, Carl, Cao, Rui, Sarangi, Ritimukta, Hou, Changmin, Chen, Zuolong, Zhang, Wenhua, Wang, Nannan, Wu, Xiaofeng, Zhu, Yanqiu, Wu, Yimin A.
• Format: Article
• Language: English
• Subjects: CO oxidation; MATERIALS SCIENCE; Perovskite oxides; Surface segregation; Surface/interface electronic structure; Wet exsolution
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2022.129110

Cation segregation occurring near the surface or interfaces of solid catalysts plays an important role in catalytic reactions. Unfortunately, the native surface of perovskite oxides is dominated by passivated A-site segregation, which severely hampers the catalytic activity and durability of the system. To address this issue, herein, we present a wet exsolution method to reconstruct surface segregation in perovskite cobalt oxide. Under reduction etching treatment of glycol solution, inert surface Sr segregation was transformed into active Co3O4 segregation. By varying the reaction time, we achieved differing coverage of the active Co3O4 segregation on the La0.5Sr0.5CoO3-δ (LSCO) perovskite oxide surface. This study reveals that CO oxidation activity exhibits a volcano-shaped dependence on the coverage of Co3O4 segregation at the surface of a perovskite cobalt oxide. Furthermore, we find that a suitable coverage of Co3O4 segregation can dramatically improve the catalytic activity of the perovskite catalyst by enhancing interface interactions. Co K-edge, Co L-edge, and O K-edge X-ray absorption spectra confirm that the synergistic effect optimizes the covalence of the metal-oxygen bond at the surface and interface. This work not only contributes to the design and development of perovskite-type catalysts, but also provides important insight into the relationship between surface segregation and catalytic activity. [Display omitted] •Surface segregation of perovskite oxides is tuned by wet exsolution method.•A volcano-shaped dependence on the coverage of Co3O4 segregation in CO oxidation.•Perovskite oxide with appropriate segregation shows the better catalytic performance and durability.•Clarify the relationships between surface segregation, electronic structure, and catalytic activity.