Size effect of reduced graphene oxide sheets on its spectral-luminescent properties

Abstract

It was shown that the sheet size plays an important role in the formation of absorption and luminescent characteristics of nanodots based on reduced graphene oxide (rGO). The particle size of rGO before and after centrifugation was equal to 347.4 ± 86.5 and 166.8 ± 65.1 nm, respectively. After ablation of the prepared samples, the particle size has a more uniform distribution and it was equal to 308.5 ± 101.1 and 153.7 ± 35.3 nm, respectively. In the absorption spectra after centrifugation, an almost 5-fold decrease in the optical density of rGO was observed. After ablation of rGO with and without centrifugation, the shape of the absorption band changes. At the same time, rGO in dispersions without pretreatment exhibits extremely low luminescence ability. The fluorescence intensity of centrifuged samples was almost in 10 times higher. After ablation of rGO dispersions, the fluorescence spectrum strongly depends on the excitation wavelength. The maximum fluorescence intensity was obtained upon excitation at 340 nm. Fluorescence lifetime data showed that the duration of rGO luminescence decreases both after centrifugation and after ablation.