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The alkaline earth element- and cobalt-free Ni(Mn1/3Cr2/3)2O4 (NMC) spinel is adopted to form composite electrodes with an oxygen ion conductive phase for symmetrical solid oxide cells and its applicability is successfully demonstrated in both solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) modes. In a H2 or CO–CO2 atmosphere, NMC decomposes to Ni and spinel, but would quickly recover to NMC in air or pure CO2. Both NMC and NMC–Gd0.1Ce0.9O2−δ (NMC–GDC) composite electrodes reveal a high redox resistance and fast recovery, which originated from the significant difference in Gibbs free energy when NMC is subjected to reducing and oxidizing atmospheres. In SOFC mode at 800 °C, the anode supported and symmetrical cells with the NMC–GDC electrode achieve peak power densities of 1293 and 416 mW cm−2, respectively. With an applied current density of 400 mA cm−2 at 750 °C in SOFC mode, the working voltage of the symmetrical cell with the NMC–GDC electrode showed no evident decline over 96 h. In SOFC mode and under pure CO2 in the cathode, the symmetrical cell working in SOEC mode showed a faradaic efficiency of over 96% at 700–850 °C and an electrolysis current density of 2320 mA cm−2 at 850 °C with an applied voltage of 2 V. Furthermore, the applied voltage decreased from 1.507 V to 1.407 V over a 72 h running time under a static current density of 800 mA cm−2 at 800 °C. The nickel exsolution in a reduction atmosphere and the abundant transition metal element centered octahedra ensure the multi-functionality of NMC. The NMC spinel-based electrode demonstrates an extraordinary redox resistance and running stability, and it is anticipated to play a pivotal role in the future exploration of novel and stable electrodes for solid oxide cells. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 (CO2RR) is a versatile method that is capable of simultaneously reduce CO2 emission and produce valuable fuels and chemicals. However, its application is hindered by the lack of cost‐effective catalysts and significant overpotential requirement. In this work, we report a low‐cost and surfactant/capping agent free method to synthesize cubic Cu2O−SnO2 core‐shell electrocatalyst, whose thickness can be easily controlled by the content of tin precursor. The optimized Cu2O−SnO2 catalyst with a 5 nm‐thick shell achieved over 90 % faradaic efficiency towards CO at a low overpotential of 390 mV, which is comparable to some of the noble metal catalysts. The catalyst also exhibited good stability over 18 hours of test at −0.6 V vs. RHE in 0.5 M KHCO3 electrolyte. This work provides a widely applicable strategy for developing a low‐cost electrocatalyst for CO2 conversion. [ABSTRACT FROM AUTHOR]

Hydration properties and electrical characteristics of the hightemperature proton conductor La27(W0.85Nb0.15)5O55.5-δ are investigated by means of thermogravimetry, impedance spectroscopy, and the electromotive force (EMF) method as a function of temperature, water vapor, and oxygen partial pressures, as well as isotope exchange measurements in order to elucidate the mechanism and thermodynamics of protons formation and transport. The highest proton conductivity, 1.3 3 10-3 S/cm, is achieved at 700°C in wet O2. Proton selfdiffusion coefficients are estimated from thermogravimetric measurements of hydration and conductivity data. Comparison of the conductivity characteristics between nominally pure and Nb-substituted materials reveals that the ionic conductivity increases and the activation energy decreases with Nb doping. These differences are discussed to reflect changes in the structure promoting ionic transport rather than changing the concentration of defects to any large extent. [ABSTRACT FROM AUTHOR]

Hydration properties and electrical characteristics of the hightemperature proton conductor La27(W0.85Nb0.15)5O55.5-δ are investigated by means of thermogravimetry, impedance spectroscopy, and the electromotive force (EMF) method as a function of temperature, water vapor, and oxygen partial pressures, as well as isotope exchange measurements in order to elucidate the mechanism and thermodynamics of protons formation and transport. The highest proton conductivity, 1.3 3 10-3 S/cm, is achieved at 700°C in wet O2. Proton selfdiffusion coefficients are estimated from thermogravimetric measurements of hydration and conductivity data. Comparison of the conductivity characteristics between nominally pure and Nb-substituted materials reveals that the ionic conductivity increases and the activation energy decreases with Nb doping. These differences are discussed to reflect changes in the structure promoting ionic transport rather than changing the concentration of defects to any large extent. [ABSTRACT FROM AUTHOR]