Metallicity enhancement in core–shell SiO2@RuO2 nanowires

Abstract

Metallic oxide compounds have interesting applications in catalysis, in optoelectronics, and as sensitive detectors. One of these, RuO₂, is also an excellent material for charge storage. Composite core–shell nanowires formed by an inner insulating SiO₂ wire serving as scaffold to an external RuO₂ nanotube have promising uses. Electronic structure calculations reveal an interesting modification of the electronic band structure of the external oxide shell induced by the presence of the SiO₂ core. The small changes in the interatomic distances in RuO₂ as it adapts to the underlying core lead to some bands crossing the Fermi level, and to an enhancement in the metallicity of the system. As a consequence, a substantial increase of the conductance of the wires is predicted when the composite SiO₂@RuO₂ wires are accommodated between two gold electrodes. The result suggests that the small strain occurring as metal-oxide wires adapt to the insulating core can be used to tailor the electrical conductance.