Recent trends on functional metal-oxide nanosystems: a closer look

Over the past decade, the unprecedented developments of nanotechnologies, in conjunction with their convergence with molecular science, has fuelled an impressive boost for forefront research in different fields, from catalysis and sensing to environment and safety, from optics to optoelectronics. The final goal of this scientific endeavor is the ability to develop functional nanosystems (composites, nanorods, clusters arrays and complex architectures) for sustainable development, featuring intelligent properties and specific functions. Advanced trends in the synthesis of inorganic nanosystems rely on the optimization of bottom-up approaches, allowing to tailor the system morphogenesis and properties according to the desired applications. In this context, Sol-Gel and vapor-phase routes, such as sputtering and Chemical Vapor Deposition (CVD), enable the design and chemical modification of composition, nanostructure and morphology of the final product under soft and controlled conditions. An open challenge for forefront research is provided by innovative hybrid strategies based on the synergic combinations of the above routes, opening new horizons for the development of functional advanced nanosystems. This presentation will be focused on the most interesting results obtained in the tailored synthesis of metal-oxide inorganic nanosystems. In particular, attention and emphasis will be paid to the following case studies: • Columnar CeO2 nanostructures obtained by CVD, and their subsequent applications in solid state gas sensing devices; • ZnO nanoplatelets and ZnO-TiO2 nanocomposites, synthesized for the first time by CVD, of great interest for eventual applications in the detection of volatile organic compounds and in their conversion into non-toxic products; • Au/TiO2 nanocomposites prepared by sputtering of gold on titania xerogels obtained by a Sol-Gel route, and their utilization as innovative photocatalysts; • SiO2-sandwiched Au nanoparticle arrays (SiO2/Au/SiO2), of great interest in optics and optoelectronics, obtained by sputtering of gold NPs followed by subsequent Plasma Enhanced-CVD of a silica encapsulating layer. Selected relevant results obtained by an extensive chemical and physical system characterization will be presented and discussed.