Fluorescent graphene oxide derived from carbonized citric acid for copper(II) ions detection

Fluorescent graphene oxide (GO) nanoparticles were obtained from the thermal carbonization of citrate acid. Depending on the synthesizing temperature, the size of GO varied from several to several hundred nanometers. Owing to the confinement from the size, green and blue emissions at around 504 and 450 nm were observed from the GO suspension. These emissions could be dynamically quenched by titrating against copper (II) (Cu2+) ions, and the emission intensity was reduced exponentially as a function of Cu2+ concentration. The quenching mechanism was ascribed to the bridging of the surface -COOH and -OH groups by Cu2+, which restricted the vibration of edge atoms or clusters and reduced the number of luminophores of GO nanosheets. As a result, the concentration of Cu2+ was detectable with the fluorescent intensity of GO.

Automated summary

Fluorescent graphene oxide (GO) nanoparticles were synthesized via thermal carbonization of citrate acid, with the size of GO ranging from several to several hundred nanometers depending on the synthesizing temperature. The emission of green and blue light from the GO suspension could be dynamically quenched by Cu2+ ions, with the fluorescence intensity decreasing exponentially with Cu2+ concentration. The quenching mechanism was attributed to the bridging of -COOH and -OH groups on the GO surface by Cu2+, restricting vibration of edge atoms or clusters and reducing the number of luminophores. The concentration of Cu2+ could be detected by the fluorescent intensity of GO.