Artículos SCI

This work reports the preparation, by a new remote assisted plasma deposition process, of luminescent nanocomposite thin films consisting of an insoluble organic matrix where photonically active perylene molecules are embedded. The films are obtained by the remote plasma deposition of adamantane and perylene precursor molecules. The results show that the adamantane precursor is very effective to improve the perylene–adamantane nanocomposite transparency in comparison with plasma deposited perylene films. The plasma deposited adamantane films have been characterized by secondary-ion mass spectrometry and FT-IR spectroscopy. These techniques and atomic force microscopy (AFM) have been also used for the characterization of the nanocomposite films. Their optical properties (UV–vis absorption, fluorescence, and refractive index) have been also determined and their sensing properties toward NO₂ studied. It is found that samples with the perylene molecules embedded within the transparent plasma deposited matrix are highly sensitive toward this gas and that the sensitivity of the films can be adjusted by modifying the aggregation state of the perylene molecules, as determined by the analysis of their fluorescence spectra. By monitoring the fluorescence emission of these films, it has been possible to detect a NO₂ concentration as low as 0.5 ppm in air at room temperature. Because of their chemical stability and transparency in the UV region, the remote plasma deposited adamantane thin films have revealed as an optimum host matrix for the development of photonically active composites for sensing applications.

A series of V₂O₅- and Co₃O₄-modified ceria/alumina supports and their corresponding gold catalysts were synthesized and their catalytic activities evaluated in the CO oxidation reaction. V₂O₅-doped solids demonstrated a poor capacity to abate CO, even lower than that of the original ceria/alumina support, owing to the formation of CeVO₄. XRD, Raman spectroscopy, and H₂-temperature programmed reduction studies confirmed the presence of this stoichiometric compound, in which cerium was present as Ce³⁺ and its redox properties were avoided. Co₃O₄-doped supports showed a high activity in CO oxidation at subambient temperatures. The vanadium oxide-doped gold catalysts were not efficient because of gold particle agglomeration and CeVO₄ formation. However, the gold–cobalt oxide–ceria/alumina catalysts demonstrated a high capacity to abate CO at and below room temperature. Total conversion was achieved at −70 °C. The calculated apparent activation energy values revealed a theoretical optimum loading of a half-monolayer.