acts with the catalyst it first adsorbs on the metal surface, weakening the HH chemical bond and dissociating into two atomic species. These atomic hydrogens are then free to diffuse on the metal surface and, when reaching the border of the metallic nanostructure, to migrate on the tungsten oxide. The latter migration step is also known as "spillover." When the hydrogen atoms reach the oxide surface, they can easily diffuse within the bulk and spontaneously react reducing the valence state of tungsten atoms from 6+ to 5+, forming tungsten bronze H x WO 3 , which appears blue under visible light.This gasochromism effect can provide major improvements in modern sensing technologies, as this material can be used as an optical transducer material for hydrogen sensing. Considering that many

In this work, we investigated the possible incorporation of YAG (yttrium aluminum garnet)-Ce particles into plasma electrolytic oxidation (PEO) coatings on 1050AA (aluminum alloy) in order to endow the surface with photoluminescent properties. Different treatment times and current modes (direct or pulsed) were tested as PEO process parameters using as electrolyte a silicates-containing solution. The microstructure of the samples was characterized by SEM and XRD measurements, the corrosion properties were determined by EIS tests, whereas the photoluminescence was evaluated with a proper spectrometer. The concentration of the YAG-Ce particles incorporated in the PEO coating was strongly influenced by the current mode, and in particular, it was higher with pulsed current mode. A higher content of YAG-Ce particles results in a better corrosion resistance and photoluminescent effect. PEO process in pulsed unipolar mode using an electrolyte containing YAG-Ce particles resulted an effective way to produce samples of 1050AA with a surface characterized by photoluminescent properties.

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