Epitaxial Growth of Cu2O on Ag Allows for Fine Control Over Particle Geometries and Optical Properties of Ag-Cu2O Core-Shell Nanoparticles

We demonstrate that Ag-Cu2O core-shell nanoparticles exhibit geometry-dependent optical properties that are highly tunable across the visible and near-infrared spectral regions. We have developed a robust wet chemistry approach to the geometry control of Ag-Cu2O core-shell nanoparticles through epitaxial growth of Cu2O nanoshells on the surfaces of various Ag nanostructures, such as quasi-spherical nanoparticles, nanocubes, and nanocuboids. Precise control over the core and the shell geometries enables us to develop detailed, quantitative understanding of how the Cu2O nanoshells introduce interesting modifications to the resonance frequencies and the extinction spectral line shapes of multiple plasmon modes of the Ag cores. Finite-difference time-domain calculations provide further insights into the physical origin and the geometry-dependence of the various plasmon modes observed in the Ag-Cu2O core-shell nanoparticles.