Fig. 2. The 2D-HSQC NMR spectra of (a) AL and (b) GQDs/Gr, (c) Left to right: G, H, S, and pCA unit (d) generated aromatic conjugation in the GQD/Gr sheets. (e) Possible mechanism from lignin to GQD/Gr sheet including (I) lignin aromatic rebonding, (II) aromatic refusion into the GQDs, and (III) aromatic enlargement of the GQDs aromatic enlargement into the porous GQD/Gr sheet.