Exploring the Origin of Blue and Ultraviolet Fluorescence in Graphene Oxide.
We studied the fluorescence (FL) properties of highly exfoliated graphene oxide (GO) in aqueous solution using continuous-wave and time-resolved FL spectroscopy. The FL spectra of highly exfoliated GO showed two distinct peaks at ∼440 (blue) and ∼300 nm [ultraviolet (UV)]. The FL of GO in the UV region at ∼300 nm was observed for the first time. The average FL lifetimes of the emission peaks at ∼440 and ∼300 nm are 8-13 and 6-8 ns, respectively. The experimentally observed peak wavelengths of pH-dependent FL, FL excitation spectra, and the FL lifetimes are nearly coincident with those of aromatic compounds bound with oxygen functional groups, which suggests that the FL comes from sp(2) fragments consisting of small numbers of aromatic rings with oxygen functional groups acting as FL centers in the GO.
†Institute of Advanced Energy, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan.
Daichi
D
Kozawa
†Institute of Advanced Energy, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan.|‡Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.
Yuhei
Y
Miyauchi
†Institute of Advanced Energy, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan.
Shinichiro
S
Mouri
†Institute of Advanced Energy, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan.
Kazunari
K
Matsuda
fluorescence; graphene oxides; optical properties; photoluminescence