Growth and composition of nanostructured and nanoporous cerium oxide thin films on a graphite foil

Oxygen plasmas: a sharp chisel and handy trowel for nanofabrication

Although extremely chemically reactive, oxygen plasmas feature certain properties that make them attractive not only for material removal via etching and sputtering, but also for driving and sustaining nucleation and growth of various nanostructures in plasma bulk and on plasma-exposed surfaces. In this minireview, a number of representative examples is used to demonstrate key mechanisms and unique capabilities of oxygen plasmas and how these can be used in present-day nano-fabrication. In addition to modification and functionalisation processes typical for oxygen plasmas, their ability to catalyse the growth of complex nanoarchitectures is emphasized. Two types of technologies based on oxygen plasmas, namely surface treatment without a change in the size and shape of surface features, as well as direct growth of oxide structures, are used to better illustrate the capabilities of oxygen plasmas as a powerful process environment. Future applications and possible challenges for the use of oxygen plasmas in nanofabrication are discussed.

Correlation between deposition parameters of periodic titanium metal/oxide nanometric multilayers and their chemical and structural properties investigated by STEM-EELS

We analyze structure and composition of titanium-based metal/oxide periodic multilayers prepared by reactive sputtering. The reactive gas pulsing process is involved to periodically inject the oxygen gas during the multilayers deposition. This approach allows the growth of regular and tunable nanometric TiO₂/Ti periods with thicknesses ranging from 14 to 50nm. The interfacial layer between oxide and metallic layers is mainly the fcc-TiO phase as clearly pointed out by transmission electron microscopy and associated electron spectroscopies. In addition, sharp transitions are produced at Ti/TiO₂ interfaces (with a high density of defects) whereas the smoothest ones are obtained at TiO₂/Ti interfaces. Similarly, the real-time measurements of the target voltage vs. time correlate with periodic alternations formed by a mixture of amorphous+rutile TiO₂ compound, the fcc-TiO phase and the hcp metallic Ti phase through the films thickness. An abrupt transition from metallic to oxidized sputtering mode takes place when oxygen is injected and correlates with the sharp Ti/TiO₂ interface. On the other hand, when oxygen is stopped, the restoration to the metallic sputtering mode is longer and corresponds to the occurrence of the fcc-TiO phase at the smooth TiO₂/Ti interfaces.

Oxide-based nanomaterials for fuel cell catalysis: the interplay between supported single Pt atoms and particles

Nanomaterials coated with atomically dispersed platinum on ceria are structurally dynamic and show high potential for applications in fuel cells.