Plasmonic molybdenum trioxide quantum dots with noble metal-comparable surface enhanced Raman scattering

Abstract

We propose a one-pot solution strategy to prepare sub-stoichiometric MoO₃ quantum dots (MoO_3−χ-QDs) with single-layered, vacancy-containing and few-crystalline features, which display surface plasmon resonance (SPR) in both visible and near-infrared regions without illumination. In a biosensing system, they show high sensitivity and optimum SPR absorption, differing from that of MoO₃ nanosheets. Importantly, MoO_3−χ-QDs show outstanding surface enhanced Raman scattering (SERS) performance (with an enhancement factor up to 10⁶ and a detection limit as low as 10⁻⁹ M), which outperforms previously reported semiconductors and is comparable to noble metals. This remarkable SERS activity is the first obtained in metal oxide QDs, which opens a promising avenue for the development of high-sensitivity, non-noble metal-based SERS substrates.