RESUMEN
Solid oxide cells (SOCs) can switch between fuel cell and electrolysis cell modes, which alleviate environmental and energy problems. In this study, the La0.3Sr0.7Fe0.9Ti0.1O3-δ (LSFTi 91) perovskite is innovatively used as a symmetric electrode for solid oxide electrolysis cells (SOECs) and solid oxide fuel cells (SOFCs). LSFTi 91 exhibits a pure perovskite phase in both oxidizing and reducing atmospheres, and the maximum conductivity in air and 5% H2/Ar is 150 and 1.1 S cm-1, respectively, which meets the requirement of the symmetric electrode. The polarization resistance (Rp) at 1.5 V is as low as 0.09 Ω cm2 in the SOEC mode due to the excellent CO2 adsorption capacity. The current density can reach 1.9 A cm-2 at 1.5 V and 800 °C, which is the highest electrolytic performance in the reported single-phase electrodes. LSFTi 91 also exhibits eminent oxygen reduction reaction and hydrogen oxidation reaction (ORR and HOR) activities, with Rp of 0.022 and 0.15 Ω cm2 in air and wet H2, respectively. The peak power density of SOFC could reach 847 mW cm-2 at 800 °C. In addition, good reversibility is confirmed in the cyclic operation of SOFC and SOEC.
RESUMEN
The development of cathode materials with high catalytic activity and low cost is a challenge for CO2 electrolysis based on solid oxide electrolysis cells. Herein, we report a low-cost and highly active metallic Fe nanoparticle-decorated Ruddlesden-Popper (La, Sr)FeO4+δ cathode catalyst (Fe-RPLSF), which shows a high oxygen vacancy concentration and robust CO2 reduction rate. At 850 °C, the current density of the electrolysis cell with the Fe-RPLSF cathode reaches -1920 mA cm-2 at a voltage of 1.5 V, and the Faraday efficiency is as high as 100%. The polarization resistance at low frequency (0.1-10 Hz), which is the rate-limit step for CO2 electrolysis, significantly decreases with the exsolved Fe nanoparticles because of improved CO2 dissociative adsorption. Moreover, our electrolysis cell demonstrates acceptable short-term stability for direct CO2 electrolysis.
RESUMEN
The intermediate operating temperatures (~400-600 °C) of reversible protonic ceramic fuel cells (RePCFC) permit the potential use of ammonia as a carbon-neutral high energy density fuel and energy storage medium. Here we show fabrication of anode-supported RePCFC with an ultra-dense (~100%) and thin (4 µm) protonic ceramic electrolyte layer. When coupled to a novel Ru-(BaO)2(CaO)(Al2O3) (Ru-B2CA) reversible ammonia catalyst, maximum fuel-cell power generation reaches 877 mW cm-2 at 650 °C under ammonia fuel. We report relatively stable operation at 600 °C for up to 1250 h under ammonia fuel. In fuel production mode, ammonia rates exceed 1.2 × 10-8 NH3 mol cm-2 s-1at ambient pressure with H2 from electrolysis only, and 2.1 × 10-6 mol NH3 cm-2 s-1 at 12.5 bar with H2 from both electrolysis and simulated recycling gas.
