Search

X-ray absorption spectroscopy measurements were performed for the C K-edge of Pt nanoparticles on Ar+-irradiated carbon supports in order to elucidate the origin of improved catalyst performance after the introduction of vacancies into the carbon support. We observed a change in the electronic structure at the interface between the Pt nanoparticles and the carbon support after vacancy introduction, which is in good agreement with theoretical results. The results indicated that vacancy introduction resulted in a drastic change in the Pt–C interactions, which likely affected the d-band center of the Pt nanoparticles and led to the enhancement of the oxygen reduction reaction in catalysts. [ABSTRACT FROM AUTHOR]

In this work, coherent phonons in glassy carbon using transient reflection measurements with the pump-probe spectroscopy are investigated. Detection of coherent oscillation of optical phonons in a polished glassy carbon sample is enabled by wavelength-selected measurements for reflected probe pulse. We demonstrate that the G and D mode oscillations occur at 46.8 and 38.2 THz frequency, respectively, and have approximately the same lifetime of 0.17 ps. Furthermore, we find that the D mode peak is anisotropic and spreads towards lower energies. [Display omitted] • Femtosecond transient reflection signal showed a coherent oscillation of optical phonons in a polished glassy carbon. • Wavelength selective detection with an optical bandpass filter enhanced the phonon oscillation. • Both G and D mode oscillations had approximately the same lifetime of 0.17 ps. [ABSTRACT FROM AUTHOR]