Abstract
One of the effective strategies to enhance the activity and stability of the Pt-based catalysts in low-temperature solid oxide fuel cells (LT-SOFCs) is modifying the electronic structure and reducing the surface energy of Pt by transition metal alloying. Herein, co-sputtered Pt/Ti alloy cathodes for LT-SOFC with varying Pt/Ti compositional ratios (Ti 0–26 at%) are fabricated and tested. The cell constructed with the optimal (6–11 at% Ti) Pt/Ti alloy cathode shows five times lower degradation rate in activation resistance compared to a pure Pt cathode at 450 °C, resulting in a 33% enhancement in the maximum power density after 2 h of operation. We show that the performance enhancement of the Pt/Ti alloy cathode at elevated temperature is due to the formation of a catalytically active and thermally stable Pt3Ti alloy phase, in which coarsening is effectively prevented as opposed to its pure Pt counterpart. Moreover, we demonstrate that Pt/Ti alloy cathodes with excessive Ti content (≥ 19 at%) suffer from the formation of a nonreactive TiO2 surface upon oxygen exposure at elevated temperature, which causes higher activation resistance.
NSTL
Elsevier