Synthesis of ultrathin and compact Au@MnO2 nanoparticles for shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS)

Abstract Shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS) based on Au@SiO 2 or Au@Al 2 O 3 nanoparticles (NPs) shows great potential to break the long‐standing limitations of substrate and surface generality of surface‐enhanced Raman scattering (SERS). However, the shell of SiO 2 or Al 2 O 3 can easily be dissolved in alkaline media, which limits the applications of SHINERS in alkaline systems. Besides that, the synthesis of Au@SiO 2 NPs can be further simplified and Au@Al 2 O 3 NPs be replaced by other NPs that are more amenable for mass production. In an attempt to make SHINERS NPs available in any systems practically, we report the synthesis of ultrathin and compact Au@MnO 2 NPs. The shell thickness of MnO 2 can be controlled down to about 1.2 nm without any pinhole. SHINERS based on such Au@MnO 2 NPs exhibits much higher Raman enhancement effect than Au@SiO 2 NPs and can be applied in alkaline systems in which Au@SiO 2 or Au@Al 2 O 3 NPs cannot be applied. Copyright © 2011 John Wiley & Sons, Ltd.