Abstract
A novel approach has been developed to synthesize slightly fluorinated graphene quantum dots (GQDs-F) through thermal cutting of highly fluorinated graphene. The fluorinated graphene with substantial structure defects is fragile and is readily attacked. The direct evaporation of abundant CFn (n = 2, 3) groups near structure defects lead to the loss of adjacent skelton C atoms, and the fluorinated graphene can be thermally cut into GQDs-F with a relatively uniform nanosize in pyrolysis at 810 K. The GQDs-F with a low F/C atomic ratio of ca. 0.03 exhibit excitation wavelength-dependent properties with multicolor photoluminescence (PL) from blue to green. At the same time, F adatoms that are most likely located at the edges of GQDs-F have a high efficiency of introducing paramagnetic centres, and GQDs-F show a strong paramagnetism because of sp3-type defects and magnetic zigzag edges. The graphene quantum dots with such multimodal capabilities should have great applied value in material science.
Highlights
Graphene quantum dots (GQDs) present outstanding photoelectric and magnetic properties due to quantum confinement and unique edge effects, which shows many potential applications in biomedical field, photovoltaic devices, spintronic devices, etc. [1,2,3,4,5,6]
We found that the CFn (n = 2, 3) groups near structure defects are like scissors in thermal defluorination, which can evaporate as C2 F4 product and greatly enlarge the structure defects of fluorinated graphene [30,31]
Groups near structure defects are like scissors in our method, which can evaporate as C2 F4 product and convert fluorinated graphene (FG) into GQDs-F in pyrolysis
Summary
Graphene quantum dots (GQDs) present outstanding photoelectric and magnetic properties due to quantum confinement and unique edge effects, which shows many potential applications in biomedical field, photovoltaic devices, spintronic devices, etc. [1,2,3,4,5,6]. Graphene quantum dots (GQDs) present outstanding photoelectric and magnetic properties due to quantum confinement and unique edge effects, which shows many potential applications in biomedical field, photovoltaic devices, spintronic devices, etc. The magnetism of GQDs, because of high edge-to-area ratio and abundant spin-polarized zigzag edge states [12,13,14], has aroused tremendous interest. There is predicted intriguing magnetism, only a few studies have experimentally revealed the magnetic properties of GQDs [2,15,16]. The magnetic measured results show most of the GQDs derived by oxidative cutting are nonmagnetic because of the saturated carboxylation of GQDs’ edges, and only few are paramagnetic [15]. To introduce sp3 -type defects or magnetic zigzag
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