Enhancing the performance of symmetrical solid oxide fuel cells with Sr₂Fe_1.5Mo_0.5O_6-δ electrodes via infiltration of Pr₆O₁₁ bifunctional catalyst

Symmetrical solid oxide fuel cells based on yttrium-stabilized zirconia (YSZ) electrolyte and Sr₂Fe_1.5Mo_0.5O_6-δ (SFM) electrode are prepared via phase-inversion and impregnation processes. The YSZ symmetrical electrolyte support is constructed using two porous frameworks and one thin-dense-membrane via phase-inversion combined with drip-coating techniques. SFM is infiltrated into the porous frameworks of the symmetric YSZ support to work as electrodes. Nanoscale Pr₆O₁₁ catalysts are further infiltrated into the electrodes to promote electrochemical performance. The optimal loading of SFM and Pr₆O₁₁ are systematically investigated. At 800 °C, with the optimal loading of SFM (12 wt%), the polarization resistance (R_p) for anode and cathode of the cell decrease to 0.19 and 0.10 Ω cm², respectively. The maximum power density (MPD) achieves 301 mW•cm⁻² in H₂ at 800 °C. After loading Pr₆O₁₁, the R_p for anode and cathode further decrease by 47% to 0.10 Ω•cm² and by 80% to 0.021 Ω•cm², respectively. And the MPD improves by 51% to 455 mW•cm⁻² (at 800 °C). These results and analysis of distribution of relaxation times demonstrate that the introduction of Pr₆O₁₁ as bifunctional catalysts is a promising approach for simultaneously improving H₂ fuel oxidation and O₂ reduction activities.