Microwave heating synthesis and visible upconversion luminescence of NaGdF₄:Yb, Er/reduced graphene oxide nanocomposites

A novel NaGdF₄:Yb, Er/reduced graphene oxide (NaGdF₄/rGO) nanocomposite have been successfully synthesized via a facile and environmentally-friendly microwave heating reaction. X-ray diffraction, scanning electron microscope, Fourier transform infrared spectroscopy, thermo-gravimetric analysis, and upconversion (UC) luminescence spectra were used to explain the morphology, microstructure and UC luminescence properties of NaGdF₄/rGO. The short rod-like NaGdF₄:Yb, Er nanoparticles with uniform size about 750 nm were attached on the surface of GO substrate. Microwave reaction time exerted a remarkable influence on the UC luminescence property and the microstructure of nanocomposite. Under the 980 nm excitation, the UC luminescence could not be detected in the sample with a microwave time of 30 min, however, the NaGdF₄/rGO with a microwave time of 120 min presented visible green UC luminescent. The possible energy transfer mechanism from the NaGdF₄:Yb, Er nanocrystals to the energy receptor in GO substrate was also investigated. The current work paves the way for their potential application in optoelectronic devices.