Construction of Multifunctional Nanoarchitectures in One Step on a Composite Fuel Catalyst through In Situ Exsolution of La0.5Sr0.5Fe0.8Ni0.1Nb0.1O3−δ

Abstract

Multifunctional nano-architecture (MNA) on catalysts have attracted great attention because of their capability to improve the performance, durability and resistance to unwanted side reactions. Such structures, however, are conventionally prepared by deposition methods, which inherently suffer from costly and time-consuming drawbacks. Here we report a simple one-step process to successfully construct a novel MNA with core-shell nanoparticles anchored at hetero-interface of dual phase oxide substrates through phase transiton and in-situ exsolution of perovskite La0.5Sr0.5Fe0.8Ni0.1Nb0.1O3-δ (LSFNNb0.1) in wet H2 (3% H2O) at 800 ℃. The core-shell nanoparticles are composed of Ni-Fe alloy core and SrLaFeO4-type layered perovskite oxide shell (RP), which synergistically improves electrochemical activity and effectively suppresses aggregation and corasening of the metallic core. The RP phase also covers the surface of perovskite bulk (SP), forming hetero-interface and preventing further decomposition of the SP phase. The RP/SP hetero-interface may improve the kinetics of surface exchange of oxygen species, resulting in the enhancement of performance and durability of the reduced LSFNNb0.1 as anode for solid oxide fuel cells (SOFCs). A doped zirconia electrolyte supported single cell with the anode achieves the maximum power density (MPD) of 0.83 W cm2 at 800 ºC in wet H2, and the corresponding polarization resistance is as low as 0.15 Ω cm2. This work further reveals the formation mechanism of the MNA through investigating the evolution of the crystal structure, composition, morphology of the LSFNNb0.1 with reducing atmosphere, temperature and reducing time. The oxygen vacancies and phase transition are found to play important roles in the formation of the MNA. The construction of MNAs in one step opens a new opportunity to design and prepare high performance and stable catalysts in the application of energy conversion and storage.