Low pressure bottom-up synthesis of metal@oxide and oxide nanoparticles: control of structure and functional properties

Experimental activity on core@shell, metal@oxide, and oxide nanoparticles (NPs) grown with physical synthesis, and more specifically by low pressure gas aggregation sources (LPGAS) is reviewed, through a selection of examples encompassing some potential applications in nanotechnology. After an introduction to the applications of NPs, a brief description of the main characteristics of the growth process of clusters and NPs in LPGAS is given. Thereafter, some relevant case studies are reported: Formation of native oxide shells around the metal cores in core@shell NPs. Experimental efforts to obtain magnetic stabilization in magnetic core@shell NPs by controlling their structure and morphology. Recent advancements in NP source design and new techniques of co-deposition, with relevant results in the realization of NPs with a greater variety of functionalities. Recent results on reducible oxide NPs, with potentialities in nanocatalysis, energy storage, and other applications. Although this list is far from being exhaustive, the aim of the authors is to provide the reader a descriptive glimpse into the physics behind the growth and studies of low pressure gas-phase synthesized NPs, with their ever-growing potentialities for the rational design of new functional materials.