Oxidation kinetics of metallic nanoparticles

The performance of nanomaterials in specific applications can be greatly affected by a thin oxide layer on the surface. In this paper we put forward a model for the oxidation kinetics of metallic nanoparticles. For very thin oxide coatings on nanoparticles, it is necessary to take into account non-linear diffusion of the rate-determining ions. Initial oxide coatings on the particles are also taken into account. We develop a phenomenological theory of oxidation by non-linear diffusion and compare it to previous linear diffusion theories. Our model calculations are in good agreement with the measured oxidation kinetics of 15 nm nickel particles, as obtained by thermogravimetry.