Solid oxide electrolysis cell (SOEC) is a potential technique to efficiently convert CO 2 greenhouse gas into valuable fuels. Thus, there is significant interest in developing highly active and stable electrocatalysts for the CO 2 reduction reaction (CO 2 RR). Herein, a Ni and F co-doping strategy is proposed to facilitate the exsolution reaction and form a new cathode, Ni−Fe alloy nanoparticles embedded in ceramic Sr 2 Fe 1.5 Mo 0.5 O 6−δ (SFM) doped with fluorine. F-doping and Ni−Fe exsolution enhance CO 2 adsorption by a factor of 2.4 and increase the surface reaction rate constant (k chem ) for CO 2 RR from 6.79 × 10 −5 to 18.1 × 10 −5 cm s −1 , as well as the oxygen chemical bulk diffusion coefficient (D chem ) from 9.42 × 10 −6 to 19.1 × 10 −6 cm 2 s −1 at 800 °C. Meanwhile, the interfacial polarization resistance (R p ) decreases by 52%, from 0.64 to 0.31 Ω cm 2 . At 800 °C and 1.5 V, an extremely high current density of 2.66 A cm −2 and a stability test over 140 h are achieved for direct CO 2 electrolysis in the SOEC.

Double perovskite oxide PrBaFe 2 O 5+δ is a potential cathode material for intermediate-temperature solid oxide fuel cells. To improve its electrochemical performance, the trivalent element Ga is investigated to partially replace Fe, forming PrBaFe 2−x Ga x O 5+δ (PBFGx, x = 0.05, 0.1, and 0.15). The doping effects on physicochemical properties and electrochemical properties are analyzed regarding the phase structures, element valence states, amount of oxygen vacancies, content of oxygen species, oxygen surface exchange coefficients (k chem ), electrochemical polarization resistance, and single-cell performance. Specifically, PBFG0.1 exhibits improved k chem, such as a 19% improvement from 4.09 × 10 −4 to 4.86 × 10 −4 cm s −1 at 750 °C, due to the increased concentration of reactive oxygen species and oxygen vacancies. Consequently, the interfacial polarization resistance is decreased by 28% from 0.057 to 0.041 Ω cm 2 at 800 °C. The subreaction steps of the oxygen reduction reaction in the PBFG0.1 cathode are further investigated, which suggests that the oxygen dissociation process is greatly enhanced by doping Ga. Meanwhile, doping Ga increases the peak power density of the anode-supported single cell by 36% from 629 to 856 mW cm −2 at 800 °C. The single cell with the PBFG0.1 cathode also exhibits good stability in 100 h of long-term operation at 750 °C.

Triple‐conducting (H+/O2−/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 PrBaCo1.92Zr0.08O5+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 PrBaCo2O5+δ cathode, accompanied by a much improved operational durability of 140 h at 600 °C.

Surface exchange coefficient (k) of porous mixed ionic-electronic conductors (MIECs) determine the device-level electrochemical performance of solid oxide cells. However, great difference is reported for k values, which are measured...

The kinetics for the oxygen reduction reaction (ORR) via porous dual-phase composites are critical for high-temperature electrochemical devices such as solid oxide fuel cells. Herein, a method is proposed to...