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From Material Design to Mechanism Study: Nanoscale Ni Exsolution on a Highly Active A-Site Deficient Anode Material for Solid Oxide Fuel Cells

Authors Gao, Yang HKUST affiliated (currently or previously)
Chen, Dengjie HKUST affiliated (currently or previously)
Saccoccio, Mattia HKUST affiliated (currently or previously)
Lu, Ziheng HKUST affiliated (currently or previously)
Ciucci, Francesco View this author's profile
Issue Date 2016
Source Nano Energy , v. 27, September 2016, p. 499-508
Summary Nonstoichiometric perovskites with active metal nanoparticles exsolved on the surface have shown promising potential in energy and environmental applications ranging from catalysis to power generation. In this work, a novel Sc-based A-site deficient perovskite material La0.4Sr0.4Sc0.9Ni0.1O3-delta (LSSN) is reported as a highly active anode for intermediate-temperature solid oxide fuel cells. The material is designed using both thermodynamical analysis and ab-initio simulations. The drop in Gibbs free energy for Ni in H-2 is substantial in comparison to the other elements, and density functional theory simulations indicate that the segregation of Ni towards the surface is energetically favored. Spherical Ni nanoparticles with well-defined boundaries are exsolved on the surface of LSSN after reduction in hydrogen, and the reduced samples show a high electrochemical catalytic activity in symmetric-cell measurements with an area specific resistance as low as 0.055 Omega cm(2) at 800 degrees C in humid H-2. Insights into the exsolution mechanism are also derived from both experiments and analytical modeling. Experimental observations show a patterned particle distribution, which is consistent with heterogeneous nucleation. The particle size evolution is investigated using the strain, reactant, and diffusion limited analytical models. The mechanistic insights gained here can be broadly applied to design more efficient materials capable of exsolution and to control the nanoparticle growth and coverage. (C) 2016 Elsevier Ltd. All rights reserved.
ISSN 2211-2855
Language English
Format Article
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