Palladium nanoparticle dispersion over the nanocrystalline WO3 through the reduction of PdCl2 by H2: characterization and gasochromic properties

In this study dispersed Pd nanoparticles (NP) over the sol-gel derived WO3 thin films were produced from the H2-reduction of deposited PdCl2 The surface chemistry of samples was studied by X-ray Photoelectron Spectroscopy (XPS). For example, after the completeness of reduction the Cl atoms are completely eliminated and a PdO/Pd° layer is produced at surface. From Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) observations, the PdCl2 layer is crystalline consisting of ~ 50 nm Pd NPs or fractal-like structures embedded in a PdCl2 matrix. They are shrinking in the reduction process and consequently a dispersion of Pd NPs is produced at the surface. The gasochromic properties in the H2/O environment for different PdCl2 amounts revealed that the rate and saturated level of colouring increases with PdCl2 amounts.

Keywords:

WO3 , Pd NPs , Hydrogen , Reduction , Gasochromic