Coating graphene oxide sheets with luminescent rare-earth complexes

Rare-earth (RE) complexes can be easily adsorbed on the surface of graphene oxide sheets (GOSs) by a simple noncovalent approach. The resulting nanocomposite materials, RE complexes functionalized GOSs, have been comprehensively characterized via transmission electron microscopy, X-ray photoelectron spectroscopy, FT-IR spectra, X-ray diffraction, and thermogravimetric analysis. The luminescence properties of GOSs-RE were also investigated. Under the excitation of UV light, these samples display the characteristic emissions of Eu3+ ions. The photophysical investigations revealed that the presence of GOSs do not quench the lanthanide-centered luminescence stemming from the characteristic electronic transitions within the 4f shell of the Eu3+ ions. The GOSs–RE complex hybrids and their dispersion can emit bright red luminescence. Moreover, the presence of GOSs can elongate the fluorescence lifetime of the RE complexes to 983 μs. These properties make them useful in many practical fields, such as in the lighting and biological labeling.