The enhancement of the surface-enhanced Raman scattering (SERS) property of the plasmonic metal oxide semiconductor nanostructures by controlling their phase, shape, size, and oxygen vacancy to detect trace amounts of organics is of significant interest. In this study, a simple surfactant-free hydrothermal strategy was proposed to fabricate crystalline h-MoO3–x and α-MoO3–x nanomaterials with tunable plasmonic properties. Herein, the crystal phase, morphology, and oxygen vacancy of MoO3–x nanostructures were precisely controlled under suitable synthetic conditions. The plasmonic properties of the as-synthesized h-MoO3–x and α-MoO3–x micro-/nanostructures were controlled by adjusting the residual volume in the autoclaving chamber. In addition, the plasmonic MoO3–x exhibited SERS activity with a detection limit as low as 1.0 × 10–9 M and the maximum enhancement factor (EF) up to 6.99 × 105 for h-MoO3–x , while for α-MoO3–x , the detection limit was 1.0 × 10–7 M with the corresponding EF up to 8.51 × 103, comparable with plasmonic noble metal nanomaterials without a “hot spot”.

No abstract

The design and synthesis of a highly sensitive and exceptionally selective surface-enhanced Raman scattering (SERS) substrate with an excellent reusable property are of significant interest because of its vast prospective application in actual and complicated detection environments. Here, a simple synthesis strategy was presented to fabricate crystalline two-dimensional (2D) MoO 2 /N-doped-carbon nanosheets with the plasmonic property. The morphology, crystal phase, and surface property of MoO 2 nanomaterials (NMs) were specifically controlled under suitable reaction conditions. In addition, the plasmonic MoO 2 /Ndoped-carbon NM exhibited a SERS maximum enhancement factor up to 1.38 × 10 4 with a detection limit as low as 1.0 × 10 −6 M. More importantly, the as-synthesized nanocomposite shows high selectivity as a "SERS Tweezer" toward methylene blue (MB) in binary and ternary mixed interfering analyte solutions, preserving detection sensitivity toward MB for three cycles via an "elect-and-eliminate" approach. This strategy will be helpful to design other plasmonic semiconductor NMs for successful tangible applications of selective SERS sensing for trace impurity detections in real and complex environments.