Preparation And Functionalization Of Graphene Quantum Dots

Graphene quantum dots?GQDs?are discovered as a class of zero-dimensional graphitic nanocrystals with tiny sizes of only several nanometers,strong quantum confinement and edge effects.GQDs possess the advantages of lower toxicity,stronger luminescence and higher photostability in comparison to conventional semiconductor quantum dots,thus making them promising in the fields of sensors,bioimaging,environmental monitoring and so on.The polystyrenic structure and the functional groups?carboxyl,phenolic hydroxyl groups?on the surface of the GQDs make it easy functionalize via?-?stacking interactions and oxygen-containing functional groups.Through the access of biological molecules,probe molecules,polymers and so on,a variety of functional materials based on graphene quantum dots were obtain for various applications.1.GQDs were fabricated from larger graphene sheets by acid oxidation method.The characteristics of GQDs were investigated using Fourier transform infrared spectroscopy?FTIR??UV–vis absorption spectrum?UV??Photoluminescent spectra?PL??Transmission electron microscopy?TEM?.GQDs with uniform size of¹0 nm,blue color was exhibited by the GQDs under ultraviolet radiation??=365nm?.On the excitation of 337nm,photoluminescent emission spectra showed a strong peak at 438 nm.This method is simple,cheap and efficient.2.GQDs were simply adsorbed by polystyrenic anion-exchange resin?PS-AERs?with the millimeter granularity between 0.3 mm to 1.2 mm.Consequently a novel solid fluorescent sensor graphene quantum dots/polystyrenic anion-exchange resin?GQDs/PS-AER?was obtained through?-?stacking interaction between PS-AER and GQDs.The characteristics of GQDs/PS-AER were studied by Attenuated total reflectance Fourier transform infrared spectroscopy?ATR-FTIR??Photoluminescent spectra?PL??Scanning electron microscopy?SEM?.Then the as-prepared GQDs-adsorbed resins were further used for the detection of Fe³⁺,the linear response range of Fe³⁺was obtained from 1?M to 7?M and the detection limit was as low as 0.65?M.In addition,the sensor could be regenerated by adding complexing agent EDTA and be separated by using simple filtration.The recovered sensor can be reused for Fe³⁺detection.3.Graphene quantum dots micelle with uniform size and multi-color are fabricated through a hydrothermal method.The color of the GQDs micelle can be modulated through simply changing experimental parameters because of Aggregation-induced emission.This synthetic method provides a simple way to produce GQDs micelle with multifarious colors.