title: Large scale preparation of graphene quantum dots from graphite with tunable fluorescence properties.
abstract: We report an improved Hummers method for synthesizing graphene quantum dots (GQDs) by directly oxidizing and etching graphite powders. The yield of GQDs is as high as 63 ± 7% (by weight, wt%), suggesting this technique is suitable for producing GQDs on a large scale. The GQDs are nanocrystals with lateral dimensions in the range of 2-4 nm and an average thickness of around 1.3 nm. The emission peaks of as-prepared GQDs can be tuned in the range of 440 to 510 nm by varying the reaction conditions. Their fluorescence quantum yields were tested to be around 1%, which could be further increased to about 3% by hydrothermal treatment. These GQDs have low cytotoxicity and excellent biocompatibility, indicating that they are promising for biological applications.
authors.affiliation: Department of Chemistry and Key Laboratory of Organic Phosphorus and Chemical Biology of Chinese Education Commission, Tsinghua University, Beijing 100084, People's Republic of China.
authors.forename: Yiqing
authors.initials: Y
authors.lastname: Sun
authors.forename: Shiqi
authors.initials: S
authors.lastname: Wang
authors.forename: Chun
authors.initials: C
authors.lastname: Li
authors.forename: Peihui
authors.initials: P
authors.lastname: Luo
authors.forename: Lei
authors.initials: L
authors.lastname: Tao
authors.forename: Yen
authors.initials: Y
authors.lastname: Wei
authors.forename: Gaoquan
authors.initials: G
authors.lastname: Shi