Chen Dengjie, Chen Chi, Zhang Zhenbao, Baiyee Zarah Medina, Ciucci Francesco, Shao Zongping
†State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 210009, China.
§Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong, China.
ACS Appl Mater Interfaces. 2015 Apr 29;7(16):8562-71. doi: 10.1021/acsami.5b00358. Epub 2015 Apr 15.
Mixed conducting perovskite oxides are promising catalysts for high-temperature oxygen reduction reaction. Pristine SrCoO(3-δ) is a widely used parent oxide for the development of highly active mixed conductors. Doping a small amount of redox-inactive cation into the B site (Co site) of SrCoO(3-δ) has been applied as an effective way to improve physicochemical properties and electrochemical performance. Most findings however are obtained only from experimental observations, and no universal guidelines have been proposed. In this article, combined experimental and theoretical studies are conducted to obtain fundamental understanding of the effect of B-site doping concentration with redox-inactive cation (Sc) on the properties and performance of the perovskite oxides. The phase structure, electronic conductivity, defect chemistry, oxygen reduction kinetics, oxygen ion transport, and electrochemical reactivity are experimentally characterized. In-depth analysis of doping level effect is also undertaken by first-principles calculations. Among the compositions, SrCo0.95Sc0.05O(3-δ) shows the best oxygen kinetics and corresponds to the minimum fraction of Sc for stabilization of the oxygen-vacancy-disordered structure. The results strongly support that B-site doping of SrCoO(3-δ) with a small amount of redox-inactive cation is an effective strategy toward the development of highly active mixed conducting perovskites for efficient solid oxide fuel cells and oxygen transport membranes.
混合导电钙钛矿氧化物是高温氧还原反应中很有前景的催化剂。原始的SrCoO(3-δ)是一种广泛用于开发高活性混合导体的母体氧化物。将少量氧化还原惰性阳离子掺杂到SrCoO(3-δ)的B位（Co位）已被用作改善其物理化学性质和电化学性能的有效方法。然而，大多数研究结果仅来自实验观察，尚未提出通用的指导方针。在本文中，通过实验和理论相结合的研究，以深入了解B位掺杂氧化还原惰性阳离子（Sc）的浓度对钙钛矿氧化物性质和性能的影响。对其相结构、电子导电性、缺陷化学、氧还原动力学、氧离子传输和电化学反应活性进行了实验表征。还通过第一性原理计算对掺杂水平效应进行了深入分析。在这些组成中，SrCo0.95Sc0.05O(3-δ)表现出最佳的氧动力学，并且对应于稳定氧空位无序结构所需的Sc的最小比例。结果有力地支持了用少量氧化还原惰性阳离子对SrCoO(3-δ)进行B位掺杂是开发用于高效固体氧化物燃料电池和氧传输膜的高活性混合导电钙钛矿的有效策略。
