Facile One-step Metal-free Fenton Fabrication Of Nitrogen-Doped Reduced Graphene Oxide Quantum Dots And Environmental Catalysis Application

Nitrogen-doped reduced graphene oxide quantum dots(N-rGQDs)was fabricated based on GO.With strong fluorescence,chemical inertness,biocompatibility and low toxicity,GQDs exhibit promising applications in bioimaging,photocatalysis,energy conversion,optoelectronics and sensing.One of the greatest challenges for GQDs fabrication originates from the strong chemical inertness and stability of GO;hence,the synthetic methods are generally complex,high energy consumption and operated under severe conditions.Moreover,the surfaces of GQDs obtained via mentioned methods are prone to involve oxygenous functional groups.Hence,we obtained N-rGQDs in one-step under room temperature and pressure using H2O2 and HA as metal-free Fenton regents.The one-step cutting,reduction and N-doping process for N-rGQDs fabrication was explored via manipulating the proportion of regents.Furthermore,N-rGQDs were applied in the environmental catalytic degradation systems.Innovative and promising results had been obtained as follows:1)N-rGQDs were obtained via the metal-free Fenton method.During GO cutting process,21%of C-O and C=O groups decline.Simultaneously,N atoms were incorporated into inter conjugated structure or cutting edges of N-rGQDs.With the proportion of HA increasing,the content of aromatic N(Nar)and tertiary amines N[Ar-N-(CH3)2]were controlled.N-rGQDs manifested promising application in environmental catalysis,thus it were used as catalyst in oxidation system.With the theoretical study based on DFT,the mechanism was explored,Nar probably played key roles during the reaction,Ar-N-(CH3)2 also made contribution to the reaction.It was feasible to fabricated catalyst with high activities.2)Porous C3N4/N-rGQDs was fabricated,and the effect of N-rGQDs structure and capacity on catalytic activities were studied.The removal rate constants of pollutants increased 1.6-1.8 times.With the aim to design catalysts with high catalytic activities,the mechanism was explored in each system.The optimum ratio was gN-rGQDs/g?? C3N4=3.4×10-5.3)With the aim to further figure out the correlation between the catalytic activity and the structure of C3N4 in composite catalyst from the morphological and structural aspects,bulk C3N4/N-rGQDs,porous C3N4/N-rGQDs and nanosheet C3N4/N-rGQDs were fabricated.The result indicated that the structure of C3N4 had great effect on catalytic activity,while the structure of the chemical bond had little effect on catalytic activity.The removal of pollutant were 58.3%,98.0%and 99.0%when choose bulk C3N4/N-rGQDs,porous C3N4/N-rGQDs and nanosheet C3N4/N-rGQDs as catalyst.The catalyst with porous structure or nanosheet structure tended to manifested high catalytic activity,which was probably due to the large surface area and exposed active sites.