Plasmonic Ag@Cu2O core–shell nanostructures exhibiting near-infrared photothermal effect

Abstract

This work was devoted to the investigation of the optical properties, structural characterization, and photothermal conversion performance of Ag@Cu₂O nanostructures. The selection of anisotropic silver core, specifically Ag nanocubes, was driven by the possibility to tune LSPR across a broader range of the electromagnetic spectrum. The thickness of the Cu₂O shell was intentionally changed through the variation in the Cu salt to the metal core nanoparticles ratios. The LSPRs of Ag(nanocube)@Cu₂O core–shell nanoparticles can be fine-tuned to the spectral region to become resonant with the excitation wavelengths of 808 nm NIR laser. Due to the high refractive index of the deposited Cu₂O, the redshifts of the plasmon band wavelength in the extinction spectra were observed. Consequently, the photothermal activities of the Ag(nanocube)@Cu₂O core–shell NPs have been controlled by the shell thickness at the nanoscale. Ag@Cu₂O nanoparticles with thickest shell (∼70 nm) exhibit the most efficient NIR photothermal effect under the irradiation of 808 nm laser at ambient conditions. Results of this work demonstrate that Ag@Cu₂O hetero-nanostructures may be optimized and used for the efficient transformation of light into other forms of energy, specifically heat.