Thermodynamically driven oxidation-induced Kirkendall effect in octahedron-shaped cobalt oxide nanocrystals

Abstract

The morphology and atomic arrangement of transition metal oxide nanoparticles play a role in their envisioned technological and industrial applications, as being key to their expected performance. In particular, the magnetic or catalytic properties of cobalt oxide nanocrystals rely on their surface energy, which strongly influences their phase stability. Herein, we report the growth mechanism of cobalt oxide nanocrystals displaying an octahedral shape with a main cavity or cracks inside, stemming from the arrangement of initial nuclei, the oxidation at the surface and a consequent Kirkendall effect, driving the final disposition of two crystalline structures in the nanocrystals.