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Perovskite-type (Bi 0.4 Sr 0.6 ) x Co 0.3 Fe 0.7 O 3−δ (BiSCF) oxides with various A-site proportions ( x = 0.7, 0.8, 0.9, 1.0 and 1.1, denoted as BiSCF407, BiSCF408, BiSCF409, BiSCF410 and BiSCF411, respectively) have been developed and investigated as cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The crystal structure of the BiSCF sample is refined based on the P m -3 m space group with perfectly cubic structure ( a = a 0 ). The cells with thick La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3−σ (LSGM) electrolyte (0.5 mm thickness) and symmetrical BiSCF electrodes are fabricated for electrocatalaytic activity test and it is found that the cell with BiSCF408 shows the lowest polarization resistance of 0.10 Ω cm 2 at 700 °C. The LSGM electrolyte-supported (∼300 μm thickness) cell with BiSCF408 cathode exhibits power densities of 0.34 and 0.46 W cm −2 at 650 and 700 °C, respectively, with humidified H 2 (∼3% H 2 O) as the fuel and ambient air as the oxidant. Over 100 h stability test at 600 °C indicates that a little performance decrease occurs but no interfacial damage happens even after the long-term operation, suggesting that BiSCF408 is a potential material for IT-SOFCs. [ABSTRACT FROM AUTHOR]

Abstract: The Ni1@Pt0.067 core–shell nanoparticles with a thin layer of Pt shell have been prepared by colloidal template method. The structure and composition of the prepared core–shell nanoparticles have been analyzed by using transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In addition, the electrochemical performance of the prepared nanoparticles has been analyzed by potentiodynamic polarization and cyclic voltammetry (CV), by testing their activity towards oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). Experimental results indicate that the Ni1@Pt0.067 particles are well distributed, with an average particle size of approximately 6 nm and shell thickness of approximately 0.5 nm–2.1 nm. Compared with Pt/C, the Ni1@Pt0.067/C nanoparticles prepared in this study show significantly improved catalytic activity towards ORR and MOR. However, with increase in methanol concentration in the electrolyte composed of 0.5 mol L−1 H2SO4 + x mol L−1 methanol (where, x = 0, 0.2, 0.5 and 1.0), the limiting current of MOR on Ni1@Pt0.067/C increase remarkably, whereas the ORR activity weakens. Based on the experimental data, we analyze the mechanism underlying the impact of methanol concentration on the ORR in Ni1@Pt0.067/C and find that the surface of Pt has a variety of activity sites. [Copyright &y& Elsevier]