Tailoring the structural stability, electrochemical performance and CO2 tolerance of aluminum doped SrFeO3

Realizing Efficient Activity and High Conductivity of Perovskite Symmetrical Electrode by Vanadium Doping for CO2 Electrolysis

Solid oxide electrolysis cells (SOECs) show significant promise in converting CO2 to valuable fuels and chemicals, yet exploiting efficient electrode materials poses a great challenge. Perovskite oxides, known for their stability as SOEC electrodes, require improvements in electrocatalytic activity and conductivity. Herein, vanadium(V) cation is newly introduced into the B-site of Sr2Fe1.5Mo0.5O6-δ perovskite to promote its electrochemical performance. The substitution of variable valence V5+ for Mo6+ along with the creation of oxygen vacancies contribute to improved electronic conductivity and enhanced electrocatalytic activity for CO2 reduction. Notably, the Sr2Fe1.5Mo0.4V0.1O6-δ based symmetrical SOEC achieves a current density of 1.56 A cm-2 at 1.5 V and 800 °C, maintaining outstanding durability over 300 h. Theoretical analysis unveils that V-doping facilitates the formation of oxygen vacancies, resulting in high intrinsic electrocatalytic activity for CO2 reduction. These findings present a viable and facile strategy for advancing electrocatalysts in CO2 conversion technologies.

Fe-Doped SDC Solid Solution as an Electrolyte for Low-to-Intermediate-Temperature Solid Oxide Fuel Cells

Ceria-based oxides, such as samaria-doped ceria (SDC), are potential electrolytes for low-to-intermediate-temperature solid oxide fuel cells (SOFCs). The sinterability of these materials can be improved by adding iron as the sintering aid. This work reveals that Fe is soluble in SDC, forming an Fe-doped SDC solid solution. It is found that the solubility is affected by the sintering temperature. Fe doping has obvious effects on electrolyte properties, including sintering characteristics, thermal expansion behaviors, and electrical conductivities in both air and hydrogen atmospheres. The conductivity obviously increases while the activation energy decreases by doping Fe. Compared with that of the bare SDC electrolyte, the performance of the single cell with the Fe-doped SDC is enhanced; for example, the peak power density is increased by 52.8% to 0.726 W cm-2 at 600 °C when humidified hydrogen is used as the fuel and ambient air is used as the oxidant. The single cell showed stable operation at 600 °C under a constant current density of 0.3 A cm-2 for 150 h. Therefore, the Fe-doped SDC solid solution shows promise as a potential electrolyte for low-to-intermediate-temperature SOFCs.

Surface Self-Assembly Protonation Triggering Triple-Conductive Heterostructure with Highly Enhanced Oxygen Reduction for Protonic Ceramic Fuel Cells

Triple-conducting (H⁺ /O^2- /e^- ) cathodes are a vital constituent of practical protonic ceramic fuel cells. However, seeking new candidates has remained a grand challenge on account of the limited material system. Though triple conduction can be achieved by mechanically mixing powders uniformly consisting of oxygen ion-electron and proton conductors, the catalytic activity and durability are still restricted. By leveraging this fact, a highly efficient strategy to construct a triple-conductive region through surface self-assembly protonation based on the robust double-perovskite PrBaCo_1.92 Zr_0.08 O_5+δ , is proposed. In situ exsolution of BaZrO₃ -based nanoparticles growing from the host oxide under oxidizing atmosphere by liberating Ba/Zr cations from A/B-sites readily forms proton transfer channels. The surface reconstructing heterostructures improve the structural stability, reduce the thermal expansion, and accelerate the oxygen reduction catalytic activity of such nanocomposite cathodes. This design route significantly boosts electrochemical performance with maximum peak power densities of 1453 and 992 mW cm^-2 at 700 and 650 °C, respectively, 86% higher than the parent PrBaCo₂ O_5+δ cathode, accompanied by a much improved operational durability of 140 h at 600 °C.