Thermodynamic modeling of copper nanoparticles oxidation

Abstract

A thermodynamic analysis of oxidation of copper nanoparticles was performed. The first step of oxidation, namely Cu2O formation on the surface of spherical copper particles (core-shell model) was considered. Our results show a spontaneous oxidation of particles at oxygen pressures well below the equilibrium oxygen pressure in bulk system and a stability of oxide shell up to higher temperatures. This surface related effect result from a negative surface contribution to the Gibbs energy of the reaction 4 Cu(s) + O2(g) = 2 Cu2O due to the higher surface energy of solid copper compared to the surface energy of Cu2O and interfacial energy on the Cu/Cu2O interface.