Abstract

In-situ exsolution is widely considered to be an efficient and cost-effective method to enhance the electrochemical performance of a ceramic anode in solid oxide fuel cells (SOFCs). In this study, by controlling the non-stoichiometry of Sr2Fe1.5Mo0.5O6-δ with A-site doping, evenly distributed Fe nano-particles (~100 nm) were obtained on surface of La0.5Sr1.5Fe1.5Mo0.5O6-δ (LSFM) when treated in hydrogen. In a redox environment, excellent exsolution-dissolution reversibility was also demonstrated. Electrical conductivity relaxation (ECR) and electrochemical impedance spectroscopy (EIS) were employed to evaluate the surface reaction kinetics change during exsolution. The surface exchange coefficient (kex) was increased by 1.5 to 2 times with Fe exsolution. Based on distribution of relaxation time (DRT) analysis, the polarization resistance (Rp) associating with surface process was reduced in the first few hours. Both results revealed an enhanced surface reaction kinetics which mainly benefits from the high catalytic activity of exsolved nano-particles to H2 adsorption and dissociation process.

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