Solid-phase synthesis of atomically thin two-dimensional non-layered MoO2 nanosheets for surface enhanced Raman spectroscopy

Two-dimensional (2D) plasmonic oxides represent a new promising type of surface-enhanced Raman spectroscopy (SERS) substrate due to their atomic uniformity and high surface activities. However, current synthesis strategies of 2D structures are largely limited to intrinsically layered compounds, and nonlayered plasmonic oxides are not easy to synthesize as 2D materials, so the development of 2D nanoarchitecture based SERS substrates is seriously hindered. Here, we report a solid–solid surface reaction strategy for the fabrication of 2D nonlayered MoO2 nanosheets with an average thickness of 2–3 unit cells. By using these 2D MoO2 nanosheets as the SERS substrate to detect trace amounts of rhodamine 6G (R6G), the limit of detection concentration can be as low as 10−7 M and the maximum enhancement factor (EF) is up to 104. We anticipate that this strategy would provide beneficial insight for the fabrication of 2D non-layered nanoarchitectures, which would expand the family of 2D plasmonic materials.