title: Hollow and concave nanoparticles via preferential oxidation of the core in colloidal core/shell nanocrystals.
abstract: Hollow and concave nanocrystals find applications in many fields, and their fabrication can follow different possible mechanisms. We report a new route to these nanostructures that exploits the oxidation of Cu(2-x)Se/Cu(2-x)S core/shell nanocrystals with various etchants. Even though the Cu(2-x)Se core is encased in a thick Cu(2-x)S shell, the initial effect of oxidation is the creation of a void in the core. This is rationalized in terms of diffusion of Cu(+) ions and electrons from the core to the shell (and from there to the solution). Differently from the classical Kirkendall effect, which entails an imbalance between in-diffusion and out-diffusion of two different species across an interface, the present mechanism can be considered as a limiting case of such effect and is triggered by the stronger tendency of Cu(2-x)Se over Cu(2-x)S toward oxidation and by fast Cu(+) diffusion in copper chalcogenides. As the oxidation progresses, expansion of the inner void erodes the entire Cu(2-x)Se core, accompanied by etching and partial collapse of the shell, yielding Cu(2-x)S(y)Se(1-y) concave particles.
authors.affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia (IIT) , via Morego 30, 16163 Genova, Italy.
authors.forename: Karol
authors.initials: K
authors.lastname: Miszta
authors.forename: Rosaria
authors.initials: R
authors.lastname: Brescia
authors.forename: Mirko
authors.initials: M
authors.lastname: Prato
authors.forename: Giovanni
authors.initials: G
authors.lastname: Bertoni
authors.forename: Sergio
authors.initials: S
authors.lastname: Marras
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie
authors.forename: Sandeep
authors.initials: S
authors.lastname: Ghosh
authors.forename: Mee Rahn
authors.initials: MR
authors.lastname: Kim
authors.forename: Liberato
authors.initials: L
authors.lastname: Manna