Restoring La1.2Sr0.8Ni0.5Mn0.5O4+δ electrocatalysis for proton-conducting solid oxide fuel cells with the elimination of bi-shell surface

Abstract

Meliorating the particle surface could alter the surface properties, thus potentially enhancing the electrode reactions. In this assignment, a recovery of the intrinsic nanostructure at La1.2Sr0.8Ni0.5Mn0.5O4+δ (LSNM) particle surface with the elimination of the bi-shell nano-surface layers caused by dopant segregation was attempted based on the lower powder calcination temperature and introduction of A-site cation deficiency. The A-site deficient (La1.2Sr0.8)0.9Ni0.5Mn0.5O4+δ [D-LSNM], accompanied with no phase separation on surface, is successfully obtained, in which the smaller particles and more oxygen vacancies would promote the electrocatalysis, oxygen reduction reaction and oxygen migration, thus boosting the electrode reactions. The surface nanostructure-recovered D-LSNM cathode achieves a preeminent performance with power output of 1547 and 1030 mW cm−2 at 700 and 600 °C, being better than other K2NiF4-type R-P cathodes in the literature. Anyhow, the preferable cell performance along with the fine stability suggests that the original surface-nanostructured D-LSNM is a promising cathode alternative for low-temperature proton-conducting solid oxide fuel cells. This work provides a new kind of reverse thinking to design highly catalytically active cathode materials via the restoration of the intrinsic nanostructure at surface, which would be beneficial to the related electrocatalytic fields.