Fig. 2

The morphologies and characterization of various GO derivatives. a–c TEM images of GQDs (scale bar = 5 nm), GQDss and TP-GQDss (scale bars = 0.5 μm); d–f AFM images of GQDs, GQDss and TP-GQDss (scale bars = 1 μm); g zeta potential of GQDs, GQDss, PEG-GQDss, TP-GQDss, TP-GQDss; h FT-IR spectra of GQDs, GQDss, PEG-GQDss, TP-GQDss; i UV absorption spectra of GQDs, GQDss, PEG-GQDss, TP-GQDss