Electrochemiluminescence Analysis And Visual Detection Of Nitrogen-doped Graphene Quantum Dots

Graphene quantum dots,due to its size is smaller than Bohr's radius,have strong quantum confinement,edge effects and been assumed numerous novel performances.In many fields,graphene quantum dots have shown potential applications,such as biomedical and biological imaging,chemical biosensors,optoelectronic devices,thermal conductors,photocatalysis and so on.In order to expand the properties and applications of graphene quantum dots,the surface modification of graphene quantum dots has attracted more and more attention.Theoretical and experimental results show that surface functionalization and heteroatom doping can effectively regulate the optical and electronic properties of graphene quantum dots,and then new phenomena and unique properties can be created.In this paper,the optical properties of graphene quantum dots were studied by nitrogen doping and surface functionalization.Moreover,three analytical methods were established for the determination of glucose,hydrogen peroxide and manganese ion(II)by electrochemiluminescence analysis and a visual method.The main contents are as follows:1.Graphene quantum dots was generated from graphene oxide sheets by exploiting the scissor cut effect after sono-and photo-chemical treatment.A sensitive electrochemiluminescence glucose biosensor based on the unique electrochemiluminescence properties of graphene quantum dot was developed.Under the optimum conditions,the decrease of ECL signal showed a linear correlation with the increase of glucose concentration(1.2?120.0 pM),and the detection limit was 0.3 pM.2.A luminol-NGQDs composite was synthesized.Luminol-NGQDs composite can produce strong anode ECL emission without additional co-reaction reagents,meanwhile,ECL-RET occurred with luminol as energy donor and NGQDs as energy acceptor.Based on the enhancement effect of hydrogen peroxide on the luminol-NGQDs ECL signal,a sensitive ECL method was developed for the determination of hydrogen peroxide.The ECL intensity increased linearly with the concentration of hydrogen peroxide in the range of 3.3×10-8?7.4×10-5 M with the correlation coefficient of 0.9986,and the detection limit was 1.0×10-8M.3.Nitrogen-doped graphene quantum dots was prepared by one-step hydrothermal method has been used to develop a new colorimetric sensing method for the detection of Mn2+without additional chemical reagents.The color of NGQDs and Mn2+ solution was changed from green to red by ultraviolet light excitation,and a new absorption peak appeared in the corresponding UV-vis absorption spectra.Based on the colorimetric method for detection Mn2+,the absorption peak intensity increased linearly with the concentration of Mn2+ in the range of 0.01?0.3 ?M and 1.0?20.0 ?M,respectively,and the detection limit was 3.0 nM.