SiO2 mesoporous thin films containing Ag and NiO nanoparticles synthesized combining sol-gel and impregnation techniques

SiO 2 sol-gel mesoporous thin films containing NiO nanoparticles have been synthesized and successively impregnated with Ag ions. A subsequent thermal treatment induces the precipitation of Ag nanoparticles and the formation of Ag/NiO interfaces. Morphological, structural and optical characterizations are used to analyze the matrix evolution with thermal annealing and to investigate the Ag + impregnation procedure and the Ag nanocrystals precipitation. NiO nanoparticles form upon annealing at 800 °C while the SiO 2 matrix is still highly porous due to the organic template removal. This porosity is useful for the impregnation process that is composed by a first pores functionalization with mercapto moieties and a second impregnation with Ag precursor solution followed by the thermal reduction of Ag ions. Optical gas sensing tests for CO and H 2 detection are presented as one of the possible applications for these noble metal-metal oxides nanocomposites