A molecular approach to RuO2-based thin films: sol–gel synthesis and characterisation

RuO2-based materials are attractive candidates for a variety of technological applications, especially in catalysis and electrocatalysis. In this field, much research is nowadays focused on the development of nanosystems, especially as thin layers, with tailored compositional and microstructural properties. In the present study, RuO2-based coatings were prepared by a sol-gel route. RuO2 nanocrystalline films were obtained by dip-coating from alcoholic solutions of Ru(OEt)3 and subsequent thermal treatments in air or N2 between 100 and 400 C. Mixed RuO2-SiO2 coatings were synthesised starting from solutions of RuCl3 and [NH2(CH2)2NH(CH2)3Si(OMe)3]. The silicon compound was used either as precursor for the silica matrix or as complexing agent for the Ru ions, to synthesise ruthenium oxide-based nanoaggregates directly in the SiO2 glass. The microstructure of the systems was studied by X-ray diffraction, while their surface and in-depth chemical composition was analysed by X-ray photoelectron spectroscopy. Furthermore, the thermal evolution of RuO2-SiO2 coatings was investigated by optical absorption.