chapter  12
55 Pages

High-Temperature Electrochemical Process of CO2 Conversion with SOCs 7

The Significant Phenomenon of Cation Segregation
WithYun Zheng, Bo Yu, Jianchen Wang, Jiujun Zhang

This chapter discusses both conventional and several state-of-the-art surface characterization technologies used in detecting surface segregation. It presents some common techniques for probing and detecting surface cation segregation in perovskite-based oxide materials. The chapter introduces the principle of operation, unique capabilities, and specific applications in investigating surface segregation and highlights advancements in characterizing surface segregation under near solid oxide cells (SOC) operation conditions. SOC electrode materials usually perform under external polarization, which is reported to impact surface segregation as well. Combining electrochemical impedance spectroscopy measurement with surface analysis, researchers attributed the performance degradation of SOC electrodes to the blocking effects of charge transfer process due to surface-bound Sr. Due to the relatively slow reaction kinetic, oxygen reduction reaction and oxygen evolution reaction activity on electrodes surface is considered to dominate the performance of SOCs. The separation of surface secondary phase is thought to be harmful to electrode performance; however, in certain cases, surface Sr enrichment may enhance oxygen surface kinetics.