Advances in synthetic strategies for metal oxide nanosystems: a non-conventional hybrid CVD/Sol-Gel approach

This paper presents a hybrid molecular approach to the synthesis of metal-oxide nanosystems. The adopted strategy is based on the CVD infiltration of a guest phase in the sponge-like structure of a xerogel host matrix prepared by the Sol-Gel route. Such a combined preparation methodology allows an intimate host-guest intermixing, resulting in chemico-physical properties widely tunable as a function of the synthesis conditions. A further ex-situ annealing can lead to the formation of different kinds of nanosystems with controlled composition, structure and morphology. In order to evidence the peculiar advantages of this method, two selected case studies are presented and discussed, namely CeO2-ZrO2 and LaCoO3 nanostructured thin films. Attention is focused on the system evolution as a function of the processing parameters, highlighting the key issues of the adopted procedure.