Plasmonic molybdenum trioxide quantum dots with noble metal-comparable surface enhanced Raman scatteringElectronic supplementary information (ESI) available. See DOI: 10.1039/c7tc04807f

We propose a one-pot solution strategy to prepare sub-stoichiometric MoO 3 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 MoO 3 nanosheets. Importantly, MoO 3− χ -QDs show outstanding surface enhanced Raman scattering (SERS) performance (with an enhancement factor up to 10 6 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. We propose a one-pot solution strategy to prepare sub-stoichiometric MoO 3 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.