Effects of surface oxidation on the linear optical properties of Cu nanoparticles

Applications of copper nanoparticles (NPs) are restricted due to their proneness to oxidation by ambient oxygen if not properly protected. Here we discuss the optical properties and application potential of copper NPs covered by a thin oxide layer. Considering Cu@Cu2O core–shell type structures with different core size and shell thicknesses, linear optical properties of surface-oxidized copper NPs have been studied theoretically. Contrary to common perception, it has been demonstrated that surface-oxidized copper NPs have certain advantages for plasmonic applications. While the position of the surface plasmon resonance (SPR) can be fine-tuned by varying the thickness of the oxide layer, their plasmonic response can be enhanced (SPR intensity gain up to 30%) by adjusting the thickness of the oxide layer.