Remarkable SERS Activity Observed from Amorphous ZnO Nanocages

Abstract Enhancement of the semiconductor–molecule interaction, in particular, promoting the interfacial charge transfer process (ICTP), is key to improving the sensitivity of semiconductor‐based surface enhanced Raman scattering (SERS). Herein, by developing amorphous ZnO nanocages (a‐ZnO NCs), we successfully obtained an ultrahigh enhancement factor of up to 6.62×10 5 . This remarkable SERS sensitivity can be attributed to high‐efficiency ICTP within a‐ZnO NC molecule system, which is caused by metastable electronic states of a‐ZnO NCs. First‐principles density functional theory (DFT) simulations further confirmed a stronger ICTP in a‐ZnO NCs than in their crystalline counterparts. The efficient ICTP can even generate π bonding in Zn−S bonds peculiar to the mercapto molecule adsorbed a‐ZnO NCs, which has been verified through the X‐ray absorption near‐edge structure (XANES) characterization. To the best of our knowledge, this is the first time such remarkable SERS activity has been observed within amorphous semiconductor nanomaterials, which could open a new frontier for developing highly sensitive and stable SERS technology.