Electrochemically Assisted Construction of a La₂NiO_4+δ@Pt Core–Shell Structure for Enhancing the Performance and Durability of La₂NiO_4+δ Cathodes

Abstract

Ruddlesden–Popper oxide La2NiO4+δ (LNO) has a high ionic conductivity and good thermal match with the electrolyte of solid oxide fuel cells (SOFCs); however, LNO suffers from performance decay owing to the La surface segregation under the operation conditions of SOFCs. Herein, we report an in situ electrochemical decoration strategy to improve the electrocatalytic activity and durability of LNO cathodes. We show that the electrochemical polarization leads to in situ construction of the LNO@Pt core–shell structure, significantly suppressing the detrimental effect of La surface segregation on the LNO cathode. The initial peak power density of a single cell with the LNO cathode is 0.71 W cm–2 at 750 °C, increasing to 1.39 W cm–2 by the in situ construction of the LNO@Pt core–shell structure after polarization at 0.5 A cm–2 for 20 h. The LNO@Pt core–shell structure is also highly durable without noticeable performance degradation over the duration of the test for 180 h. The findings shed light on the design and fabrication of highly active and durable LNO-based cathodes for SOFCs.