Hollow nanostructures based on the Kirkendall effect: Design and stability considerations

In nanoscale interdiffusion and reaction, a Kirkendall void in the core of a nanocrystal has been proposed to explain the formation of hollow nanosize particles in recent literature. We present here a simple kinetic analysis of the reaction in nanoparticles, including the effect of the Gibbs–Thomson potential. A general discussion on how to form hollow nanostructures utilizing the mechanism of the Kirkendall effect is given. Furthermore, we show that a hollow nanosize particle is thermodynamically unstable; a high-temperature aging will drive thermal vacancies to the outer surface and transform the hollow nanocrystal to a solid nanocrystal.