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A series of W doped Pr 0.5 Ba 0.5 (Co 0.7 Fe 0.3)O 3-δ (PBCF) are prepared and characterized as cathodes for proton-conducting solid oxide fuel cell (H–SOFC). The enhancement of proton migration and formation ability through W doping significantly increases the cell performance and it is further verified by the density functional theory (DFT) simulation, presenting the high valence element doping can be a potential approach for the design of cathode. • W doped PBCF at proper concentration can form Single and double perovskite composites. • The performance of H-SOECs is highly improved by applying this novel element. • Proton migration and transportation energies are calculated using DFT method. [ABSTRACT FROM AUTHOR]

Abstract: The cermet consisting of electronic conductor Ni and proton conductor La2Ce2O7 (LDC) shows good chemical stability but poor hydrogen permeability. In order to improve the hydrogen permeability, novel Ni–La2−x Sm x Ce2O7 (x =0, 0.025, 0.05, 0.075, 0.1 and 0.2) cermets were developed for hydrogen separation. The results show that Sm element doping of LDC can affect the rate of hydrogen permeation, with Ni–La1.95Sm0.05Ce2O7 possessing the highest hydrogen permeation fluxes. [Copyright &y& Elsevier]

A Zn-doping strategy is employed to tailor the LaNi 0.5 Fe 0.5 O 3-δ material to improve its performance for proton-conducting solid oxide fuel cells (H–SOFCs). Zn can partially replace Ni in the LaNi 0.5 Fe 0.5 O 3-δ lattice to form LaNi 0.4 Zn 0.1 Fe 0.5 O 3-δ material. In contrast, ZnO secondary phase can be detected if attempts are made to partially replace Fe with Zn, and the nominal composition LaNi 0.5 Fe 0.4 Zn 0.1 O 3-δ cannot be obtained. First-principles calculations indicate that the Zn-doping method lowers the formation energy of oxygen vacancy and decreases the hydration energy, benefiting its application as the cathode for H–SOFCs. As a result, the H–SOFC with the LaNi 0.4 Zn 0.1 Fe 0.5 O 3-δ cathode generates a peak power density of 1226 mW cm−2 at 700 °C. In contrast, the peak power density for the cell using the Zn free LaNi 0.5 Fe 0.5 O 3-δ cathode only reaches 722 mW cm−2 at the same testing temperature. The polarization resistance of the cell with the LaNi 0.4 Zn 0.1 Fe 0.5 O 3-δ cathode is reduced to 0.043 Ω cm2 at 700 °C, which is one of the smallest reported for H–SOFCs using cobalt-free cathodes. The high fuel cell performance coupled with the low polarization resistance for the Zn-modified LaNi 0.5 Fe 0.5 O 3-δ suggests that the Zn-doping strategy would be an interesting way to promote the performance of the cobalt-free LaNi 0.5 Fe 0.5 O 3-δ material for H–SOFCs. • A new LaNi 0.4 Zn 0.1 Fe 0.5 O 3-δ material has been prepared. • Zn-doping improved the material's properties for H–SOFCs. • High cell performance of 1226 mW cm−2 at 700 °C was obtained with the new cathode. • First-principles calculations were used to reveal the mechanism. [ABSTRACT FROM AUTHOR]

The application of traditional MIEC cathode material Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) in the solid oxide fuel cell (SOFC) field is limited due to its susceptibility to CO 2 and high thermal expansion coefficient. Therefore, improving the stability of BSCF cathode in CO 2 -containing environments and the matching degree between BSCF and electrolyte are the key factors to achieve its excellent electrochemical and stable performance for intermediate temperature solid oxide fuel cells (IT-SOFCs). Herein, the cathode materials Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2-x Ta x O 3-δ (X = 0, 0.1, 0.2) are successfully prepared and the effects of Ta-doped content are investigated systematically. With the increase of Ta-doped content, the thermal expansion coefficient of BSCF 0.2-x T x decreases from 25.1 × 10−6 K−1 to 16.5 × 10−6 K−1, which indicated that Ta-doped enhanced the combination of cathode material and electrolyte. In single-cell applications, the maximum power density of 926.4 mW cm−2 and the lowest polarization resistance of 0.06 Ω cm2 at 700 °C are achieved. Furthermore, theoretical calculations show that the CO 2 adsorption energy of BSCFT is 0.12 eV higher than that of BSCF, indicating that BSCFT exhibited improved resistance to CO 2 corrosion compared with BSCF. It is indicated that the Ta-doping strategy has the advantage of improving both the performance and stability of BSCF cathode materials. • BSCF cathode materials doped with different concentrations of Ta were prepared. • The good stability of Ta-doped BSCF cathode materials were confirmed. • The effect of Ta doping on CO 2 resistance was analyzed by theoretical calculations. • BSCF 0.1 T 0.1 material achieved excellent fuel cell performance with good stability. [ABSTRACT FROM AUTHOR]

The synthesis of ammonia (NH 3) from electrochemical nitrogen reduction reaction (NRR) under environmental conditions is a promising technology. Compared with the traditional artificial nitrogen fixation process by the Haber-Bosch process, electrochemical nitrogen reduction reaction (NRR) requires no harsh reaction conditions. In this work, we report that Bi-doped CeO 2 nanocubes show high NRR activity as electrocatalysts. The NH 3 yield of 17.83 μgh−1 mg−1 cat. and the Faradaic Efficiency (FE) of 1.61% at −0.9 V are achieved in 0.1 M Na 2 SO 4. The performance is much higher than that for the traditional CeO 2 nanoparticles. The detailed analysis indicates that both the Bi doping and the cube morphology are critical for this encouraging NRR performance. The mechanism for improving NRR is further explored with first-principle calculations, demonstrating the importance of Bi-doping for performance enhancement. • Nano Bi 0.2 Ce 0.8 O 2-δ with cube shape shows high NRR performance. • Bi-doping is critical for the high performance. • Insights for reaction mechanism were revealed with first principle calculations. [ABSTRACT FROM AUTHOR]