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
Guangxi Institute Fullerene Technology (GIFT), State Key Laboratory of Featured Metal Resources and Advanced Materials, School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China; Department of Mechanical and Mechatronics Engineering, Waterloo Institute for Nanotechnology, Materials Interface Foundry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
Department of Mechanical and Mechatronics Engineering, Waterloo Institute for Nanotechnology, Materials Interface Foundry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
J Hazard Mater. 2022 Aug 15;436:129110. doi: 10.1016/j.jhazmat.2022.129110. Epub 2022 May 10.
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 CoO segregation. By varying the reaction time, we achieved differing coverage of the active CoO segregation on the LaSrCoO (LSCO) perovskite oxide surface. This study reveals that CO oxidation activity exhibits a volcano-shaped dependence on the coverage of CoO segregation at the surface of a perovskite cobalt oxide. Furthermore, we find that a suitable coverage of CoO 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.
发生在固体催化剂表面或界面附近的阳离子偏析在催化反应中起着重要作用。不幸的是，钙钛矿氧化物的原始表面主要由钝化的A位偏析主导，这严重阻碍了该体系的催化活性和耐久性。为了解决这个问题，在此我们提出一种湿离析法来重构钙钛矿钴氧化物中的表面偏析。在乙二醇溶液的还原蚀刻处理下，惰性表面的Sr偏析转变为活性的CoO偏析。通过改变反应时间，我们在LaSrCoO（LSCO）钙钛矿氧化物表面实现了活性CoO偏析的不同覆盖率。这项研究表明，CO氧化活性对钙钛矿钴氧化物表面CoO偏析的覆盖率呈现出火山形的依赖关系。此外，我们发现合适的CoO偏析覆盖率可以通过增强界面相互作用显著提高钙钛矿催化剂的催化活性。Co K边、Co L边和O K边X射线吸收光谱证实，这种协同效应优化了表面和界面处金属-氧键的共价性。这项工作不仅有助于钙钛矿型催化剂的设计和开发，还为表面偏析与催化活性之间的关系提供了重要的见解。
