Tailoring the electrochemical reduction kinetics of dual-phase BaCe0.5Fe0.5O cathode via incorporating Mo for IT-SOFCs

Abstract

The BaCe0.5Fe0.5O3-δ (BCF) cathode consists of the ion-electron mixed conducting phase BaCe0.15Fe0.85O3-δ (BCF1585) and the proton-conducting phase BaCe0.85Fe0.15O3-δ (BCF8515). In this paper, the electrochemical performance is improved by incorporating the high valence element Mo into the BCF and applied to intermediate-temperature solid oxide fuel cells (IT-SOFCs). High-temperature X-ray diffraction (HT-XRD) and O2-temperature programmed desorption (O2-TPD) results show that Mo doping enhances the structural stability of BCF. The X-ray photoelectron spectroscopy (XPS) results suggest that the introduction of Mo increases the amount of adsorbed oxygen and thus the oxygen reduction reaction (ORR) catalytic activity. Compared to BCF, the polarization impedance of BaCe0.5Fe0.45Mo0.05O3-δ (BCFM) at 800°C is 0.154 Ω·cm2, a reduction of 22%. Meanwhile, the BCFM output power at 800°C is 778.01 mW·cm-2, an improvement of 32.17%, and maintains a stable current density after 250 h at 0.7 V. The results demonstrate that Mo doping is an effective strategy to enhance the electrochemical performance of BCF.