Study On The Graphene Oxide Sheets Coating With Luminescent Rare-earth Complexes And Its Fluorescence Properties

Graphene, a sp2hybridized carbon sheet with a honeycomb structure, has drawnmuch attention with its extraordinary characteristics such as the nanostructural property,electrical conducting, exceptionally high specific surface area to2675m2/g and its highmechanical strength. Graphene has been produced by many methods including scotch tapemethod, electrostatic deposition of graphene, thermal, chemical and mechanicalexfoliation, chemical vapour deposition, electrolytic exfoliation etc. So far, differentpotential applications in different fields have been reported such as nanoelectronics, sensors,batteries, supercapacitor, organic photovoltaic devices and so on. Recently, graphene oxidesheets (GOSs) have been extensively studied as promising precursors for the bulkproductions of graphene. GOSs are hydrophilic because it has many polar functionalgroups, such as carboxyl, hydroxyl and epoxy groups, on the nanosheets. Therefore, GOSsare not only suspendable in polar solvents but also is easily altered to form functionalgraphene for different requirements. Compared to zero-gap graphene, GOSs also haveweakly flurescent as a result of a defect-related optical gap, which may extend theirapplication to the lighting and displays fields. However, when used in practice, thephotoluminescent of GOSs needs to be enhanced. Therefore, it is significant to search amethod to modify GOSs with luminescence complexes.Rare-earth (RE) complexes can be easily adsorbed on the surface of graphene oxidesheets (GOSs) by a simple noncovalent approach. The resulting nanocomposite materials, REcomplexes functionalized GOSs, have been comprehensively characterized via transmissionelectron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), FT-IR spectra, x-raydiffraction (XRD), thermogravimetric analysis (TGA). The luminescence properties ofGOSs-RE were also investigated. Under the excitation of UV light, these samples display thecharacteristic emissions of Eu3+ions. The photophysical investigations revealed that thepresence of GOSs do not quench the lanthanide-centered luminescence stemming from thecharacteristic electronic transitions within the4f shell of the Eu3+ions. The GOSs-REcomplex hybrids and their dispersion can emit bright red luminescence. Moreover, thepresence of GOSs can elongate the fluorescence lifetime of the RE complexes to983μs.These properties make them useful in many practical fields, such as in the lighting andbiological labeling.