Scan dimension icon system

A FLS980 Fluorescence Spectrometer from Techcomp (China) Ltd was used to measure the photoluminescence quantum yield. The morphology of the prepared CDs was investigated using transmission electron microscopy (TEM) (Model JEM2100). The atomic force microscopy (AFM) images were measured using a Bruker Scan-Dimension-Icon System. The ultraviolet-visible (UV-Vis) absorption spectra of the samples were measured using a UV-Vis spectrometer (Jasco V-570). A Bruker Vertex 70v was employed for the measurement of the Fourier transform infrared (FTIR) spectra. The fluorescence measurements were carried out using a Cary Eclipse fluorescence spectrophotometer (Varian, Inc.). The solutions of the prepared CDs were placed in a quartz fluorescence cuvette. The emission slits and excitation slits were set at 2.5 nm and 5 nm, respectively. Elemental analysis was performed using X-ray photoelectron spectroscopy (XPS) (ESCALAB 250 spectrometer). Raman spectroscopy was performed by employing a Horiba Jobin Yvon Xplora confocal Raman microscope at room temperature.

Photoluminescence (PL) spectrum, UV-vis absorption spectrum, QY as well as PL lifetime were recorded using fluorescence spectrometer (FLS980) from Techcomp (China). Transmission electron microscopy (TEM), Model JEM-2100 and JEM-2100F-JEOL, was used to characterize the surface morphology of the prepared CDs. Subsequently, high-resolution TEM (HRTEM) images of the as-prepared CDs were obtained with a Model JEM-2100 transmission electron microscope. The solution was drop-casted onto mica substrates for Atomic force microscopy (AFM) investigations by using the Bruker Scan-Dimension-Icon System. X-ray photoelectron spectroscopy (XPS) were collected on a Thermo Scientific ESCALAB 250 Multi-technique surface analysis. A Bruker Vertex 70 spectrometer were used to measure the Fourier transform infrared (FTIR) spectrum spectra. X-ray diffraction spectroscopic (XRD) patterns were carried out by an X-ray diffraction using Cu-Kα radiation (XRD, PANalytical X'Pert Pro MPD). The photographs of CDs were taken with a mobile phone under UV light excited at 365 nm.