Au/Cu2O core/shell nanostructures with efficient photoresponses

Abstract

Metal/semiconductor nanoscale heterojunctions are of pronounced attention because of their specific structures and properties that vary in their individual counterparts and anticipated applications in photo-driven fields. A modified facile method is reported in this connection for the formation of cuprous-oxide coated gold (Au/Cu 2 O) nanostructures including octahedral, cuboctahedral and flower-like structures using cubic and multi-faceted gold nanostructures as the core material. The well-organized shape growth of the Cu 2 O-shell is accomplished via an adequate adjustment of the ratio H 2 O:NH 2 OH · HCl in the solution. The effect of nanoparticle's shape and thickness of the shell on the optical properties of truncated-octahedra, cuboctahedra and flower-like Au/Cu 2 O nanostructures (having sizes within 90–230 nm) shows a bathochromatic shift in the surface plasmon resonance (SPR) band of the Au-core with the increase of shell thickness. A comparative study to correlate the photoluminescence analyses of core/shell nanostructures with their photocatalytic activities shows that truncated-octahedra and nanoflowers, bounded by {111} facets, are photocatalytically more active. On the other hand, cuboctahedra with more {100} catalytically inactive sites reveal a comparatively sharp emission peak. These photoresposes are also appeared to be affected by SPR coupling between plasmonic metal-core and semiconducting-shell.