Fig. 1. The optical micrograph and ultraviolet excitation autofluorescence images of the cross section of the Vitis vinifera (a, c) and Eupatorium adenophorum (b, d)

Fig. 2. SEM images of carbon microspheres by using xylose (a), glucose (b), and sucrose (c) as carbon sources and their size distribution (d)

Fig. 3. SEM images and size distribution of carbon microspheres by using Vitis vinifer(a, c) and Eupatorium adenophorum (b, d) as carbon sources

Fig. 4. FTIR spectra of biomass raw material and carbon microspheres prepared from biomass material (a) and FTIR spectra of carbon microspheres prepared from different carbon sources (b)
Biomass raw materials: v: Vitis vinifera; e: Eupatorium adenophorum; Carbon microspheres: c-v: Vitis vinifera; c-e: Eupatorium adenophorum; c-x: xylose; c-g: glucose; c-s: sucrose

Fig. 5. Score plot (a) and loading plot (b) of principle component analysis of carbon microspheres

Fig. 6. XPS of C(1s) (a) and O(1s) (b) curving fitting for glucose carbon spheres