Strategy to Enhance the Luminescence of Lanthanide Ions Doped MgWO4 Nanosheets through Incorporation of Carbon Dots

Highly fluorescent nanomaterials have shown great potential application in optics area. However, further improving their fluorescence properties especially for nanomaterials still remains a challenge. Specifically, luminescence of lanthanide (Ln) ions doped two-dimensional (2D) nanosheets is seldom studied. Herein, MgWO4:Ln3+ (Ln = Eu, Tb) nanosheets were successfully synthesized via a simple hydrothermal method, and the luminescence properties of these nanosheets are obviously improved through incorporation of fluorescent carbon dots (CDs) onto the surface of MgWO4:Ln3+ (CDs@MgWO4:Ln3+) nanosheets. The obtained MgWO4:Ln3+ samples have a 2D nanosheet morphology with triclinic phase, and the morphology and phase structure can be maintained after incorporating CDs onto the nanosheets' surface. Under the excitation of UV light, the obtained MgWO4:Ln3+ nanosheets exhibit the characteristic emission of the doping ions, and the emission intensity of CDs@MgWO4:Eu3+ and CDs@MgWO4:Tb3+ nanosheets increases 2- and 7-fold compared to the corresponding samples without incorporation of CDs, respectively. This luminescent enhancement mechanism might be due to the capturing electrons by CDs and energy transfer from CDs to luminescent Ln3+. The fluorescence enhancement through incorporation of CDs provides a simple and environment-friendly strategy for further improving luminescence property of other lanthanide ions doped nanomaterials.