Enhanced Bifunctional Catalytic Activity of Manganese Oxide/Perovskite Hierarchical Core-Shell Materials by Adjusting the Interface for Metal-Air Batteries

Shanshan Yan; Yejian Xue; Shihua Li; Guangjie Shao; Zhaoping Liu

doi:10.1021/acsami.9b06141

Enhanced Bifunctional Catalytic Activity of Manganese Oxide/Perovskite Hierarchical Core-Shell Materials by Adjusting the Interface for Metal-Air Batteries

ACS Appl Mater Interfaces. 2019 Jul 24;11(29):25870-25881. doi: 10.1021/acsami.9b06141. Epub 2019 Jul 11.

Authors

Shanshan Yan^{1

2}, Yejian Xue¹, Shihua Li¹, Guangjie Shao², Zhaoping Liu¹

Affiliations

¹ Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Zhejiang 315201 , P. R. China.
² State key Laboratory of Metastable Materials Science and Technology, College of Environmental and Chemical Engineering , Yanshan University , Qinhuangdao 066004 , P. R. China.

PMID: 31259515
DOI: 10.1021/acsami.9b06141

Abstract

LaMnO₃ perovskite is one of the most promising catalysts for oxygen reduction reaction (ORR) in metal-air batteries and can be compared to Pt/C. However, the low catalytic activity toward oxygen evolution reaction (OER) limits its practical application in rechargeable metal-air batteries. In this work, the MnO₂/La_0.7Sr_0.3MnO₃ hierarchical core-shell composite materials with a special interface structure have been designed via the selective dissolution method. The core of La_0.7Sr_0.3MnO₃ particles is wrapped by the porous and loose MnO₂ nanoparticles. The as-prepared MnO₂/La_0.7Sr_0.3MnO₃ materials have excellent catalytic activity toward ORR/OER and are used as bifunctional oxygen electrocatalysts for metal-air batteries. Based on results of transmission electron microscopy, X-ray photoelectron spectroscopy, valence-band spectroscopy, and O₂ temperature-programmed desorption analysis, we conclude that the bifunctional catalytic activity of the MnO₂/La_0.7Sr_0.3MnO₃ materials can be effectively promoted due to the specific interface structure between the La_1-xSr_xMnO₃ core and the MnO₂ shell. This can be attributed to three aspects: (a) the electronic conductivity, which is beneficial for providing the faster charge-transfer paths and kinetics at the oxide/solution interface than that of the MnO₂ sample; (b) the enhancement of oxygen adsorption capacity due to surface defects (oxygen vacancies) and chemical adsorption, which is helpful to improve the reaction kinetics during the process of oxygen catalysis; and (c) the tuning of oxygen adsorption ability via the moderate Mn-O bond strength, which may be conducive to getting for obtain an enhanced Mn-O bond strength on the surfaces for ORR and a weakened Mn-O bond in the lattice for OER.

Keywords: bifunctional oxygen electrocatalyst; hierarchical core−shell; metal−air battery; perovskite; transition-metal oxide catalysts.