Remarkable SERS Activity Observed from Amorphous ZnO Nanocages

Here, by developing amorphous ZnO nanocages (a-ZnO NCs), we successfully obtained an ultrahigh enhancement factor up to 6.62×105. This remarkable SERS sensitivity can be attributed to high-efficiency ICTP within a-ZnO NCs-molecules system, which is caused by metastable electronic states of a-ZnO NCs. First-principles density functional theory (DFT) simulation further confirmed stronger ICTP in a-ZnO NCs than the crystalline counterpart. 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 to observe the remarkable SERS activity within amorphous semiconductor nanomaterials, which could open a new frontier for developing highly sensitive and stable SERS technology.