Hollow Au–Cu₂O Core–Shell Nanoparticles with Geometry-Dependent Optical Properties as Efficient Plasmonic Photocatalysts under Visible Light

Hollow Au–Cu₂O core–shell nanoparticles were synthesized by using hollow gold nanoparticles (HGNs) as the plasmon-tailorable cores to direct epitaxial growth of Cu₂O nanoshells. The effective geometry control of hollow Au–Cu₂O core–shell nanoparticles was achieved through adjusting the HGN core sizes, Cu₂O shell thicknesses, and morphologies related to structure-directing agents. The morphology-dependent plasmonic band red-shifts across the visible and near-infrared spectral regions were observed from experimental extinction spectra and theoretical simulation based on the finite-difference time-domain method. Moreover, the hollow Au–Cu₂O core–shell nanoparticles with synergistic optical properties exhibited higher photocatalytic performance in the photodegradation of methyl orange when compared to pristine Cu₂O and solid Au–Cu₂O core–shell nanoparticles under visible-light irradiation due to the efficient photoinduced charge separation, which could mainly be attributed to the Schottky barrier and plasmon-induced resonant energy transfer. Such optical tunability achieved through the hollow cores and structure-directed shells is of benefit to the performance optimization of metal–semiconductor nanoparticles for photonic, electronic, and photocatalytic applications