Developing highly active and stable catalysts based on earth-abundant elements for oxygen electrocatalysis is critical to enable efficient energy storage and conversion. In this work, we took advantage of the high intrinsic oxygen reduction reaction (ORR) activity of La(0.8)Sr(0.2)MnO(3-δ) (LSMO) and the high intrinsic oxygen evolution reaction (OER) activity of Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-δ) (BSCF) to develop a novel bifunctional catalyst. We used pulsed laser deposition to fabricate well-defined surfaces composed of BSCF on thin-film LSMO grown on (001)-oriented Nb-doped SrTiO3. These surfaces exhibit bifunctionality for oxygen electrocatalysis with enhanced activities and stability for both the ORR and OER that rival the state-of-the-art single- and multicomponent catalysts in the literature.

A two-dimensional array of a microcavity with a high aspect ratio is made on a Cr-coated Si surface using the micromachining technology. The thermal emission spectra whose wavelength is close to the dimension of cavity aperture (5 μm) are measured on samples with a different aspect ratio. The clear selective emission bands corresponding to the two-dimensionally confined electromagnetic modes are demonstrated experimentally. It is found that the low emissivity of the base material is essential to obtain the high spectral selectivity of thermal radiation. The direction and polarization properties are also examined. The dominant peaks of the emission spectra can be explained by a simple cavity resonator model.

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LiTi 2 O 4 is a unique compound in that it is the only known spinel oxide superconductor. The lack of high quality single crystals has thus far prevented systematic investigations of its transport properties. Here we report a careful study of transport and tunnelling spectroscopy in epitaxial LiTi 2 O 4 thin films. An unusual magnetoresistance is observed which changes from nearly isotropic negative to prominently anisotropic positive as the temperature is decreased. We present evidence that shows that the negative magnetoresistance likely stems from the suppression of local spin fluctuations or spin-orbit scattering centres. The positive magnetoresistance suggests the presence of an orbital-related state, also supported by the fact that the superconducting energy gap decreases as a quadratic function of magnetic field. These observations indicate that the spin-orbital fluctuations play an important role in LiTi 2 O 4 in a manner similar to high-temperature superconductors.