oven was used
for hydrothermal heating treatment. The FL absorption color of CB-CDs
was checked by using UV light irradiation with a long excitation wavelength
at 365 nm (Analytik Jena UVP UVGL-25). The FL spectra were recorded
by using FL spectroscopy (Varian Cary Eclipse Fluorescence Spectrophotometer).
FT-IR spectrum was obtained by using FT-IR spectroscopy (ALPHA FT-IR
Spectrometer from Bruker). The absorption spectra were recorded by
UV–vis spectroscopy (Spectra Academy UV–Vis Spectrometer
Detector SV-2100). The TEM images were scanned by a Hitachi HT-7700
microscope and JEM-3010 HR-TEM (JEOL, Japan). The Raman spectrum was
recorded on a Micro Raman Identify Spectrometer (ProTrusTech Co. Ltd.).