Facile synthesis of Au@palladium oxide nano-sunflowers for ultrasensitive surface-enhanced Raman scattering analysis

Abstract

Metal–semiconductor nanocomposites have gained more and more attention as novel surface-enhanced Raman scattering (SERS) substrates due to the coupling Raman enhancement mechanism between the nanocomponents. Herein, Au@palladium oxide (Au@PdO_x) nanohybrids are firstly obtained from the oxidation of Pd hexagonal nanosheets in the presence of Au ions, where the whole process takes no more than 5 min without any additional redox agent. Au@PdO_x shows a sunflower-like morphology with an average size of 180 nm consisting of an Au stamen and flake-like PdO_x petals. An intense electric field distribution emerges around the Au nano-stamen which endows Au@PdO_x with excellent SERS activity. A maximum Raman enhancement factor of 4.7 × 10⁷ is achieved for methylene blue with good reproducibility and reliability.