The Investigation On Fluorination And Photoluminescence Properties Of Carbon-based Materials

Among some new luminescent materials,carbon-based nanomaterials including graphene derivatives and graphene quantum dots have attracted widely attention because of more stable emissions and low cytotoxicity.There are many potential applications in biosensing field,photovoltaic devices,etc.Doping of carbon-based materials by light elements is an efficient method to modify the electric and optoelectronic properties.Fluorine atoms are capable of forming C-F bonds with higher thermal stability due to high electronegativity.Therefore,fluorination treatment is a common method for modifying the properies of carbon-based materials.In this work,we have prepared slightly fluorinated graphene quantum dots?GQDs-F?and fluorinated graphdiyne?FGDYs?,exhibiting excellent photoluminescence properties as new kind of fluorescent materials.The specific work of the paper is as follows:1.Fluorinated graphene?FG?was synthesized by directly heating a mixture of graphene and XeF₂,and then FG was thermally annealed to form some uniform slightly fluorinated GQDs-F.The prepared FG with high percent of carbon vacancy defects is fragile and easily destroyed.In the process of thermal defluorination,the CF_n?n=2,3?groups near structure defects can evaporate into C₂F₄ gas lead to the loss of adjacent skelton C atoms.The CF_n?n=2,3?groups are like scissors and the FG can be cut into uniform GQDs-F.The GQDs-F show an intrinsic blue emission,and exhibit an excitation wavelength-dependent property,emitting multicolor photoluminescence from blue to green.2.The partially fluorinated graphdiyne?FGDYs?with covalent C-F bonds and local sp²-carbon hybridization was produced by direct heating of a mixture of graphdiyne?GDY?and XeF₂.All FGDYs with different doping ratio of fluorine exhibit photoluminescence from bright blue to green when the excitation wavelength varies from 260 to 480 nm.Meanwhile,the FGDY-2 with 15.2%fluorine doping shows strong photoluminescence and the quantum efficiency is achieved to 3.7%.