Phase-controlled synthesis of molybdenum oxide nanoparticles for surface enhanced Raman scattering and photothermal therapy.

Different from their bulk counterparts, plasmonic molybdenum oxide nanomaterials display superior optical and electronic properties, but unfortunately, phase-controlled synthesis of molybdenum oxide nanomaterials with multifunctional performances still remains a challenge. To actualize this, a surfactant-free solvothermal strategy was proposed to fabricate molybdenum oxide nanomaterials with a tunable phase. Encouragingly, the as-prepared molybdenum dioxide nanoparticles (MoO2 NPs) exhibit intense near-infrared (NIR) absorption attributed to the localized surface plasmon resonance (LSPR) effect, which results in their application as a surface enhanced Raman scattering (SERS) substrate to detect trace amounts of molecular species including Rhodamine 6G (R6G), crystal violet (CV), IR-780 iodide (IR780) and methylene blue (MB). The detection limit was as low as 5 × 10-8 M and the maximum enhancement factor (EF) was up to 1.10 × 107, compared to other semiconductor nanostructures, the SERS sensitivity may be the best. Meanwhile, with the significant photothermal conversion efficiency up to 61.3%, the plasmonic MoO2 NPs could also be used as a photothermal therapy (PTT) agent for efficient photothermal ablation of cancer cells in vitro.