Fig. 1. (a) The AFM image of graphene sheets and GQDs derived from black liquor, showing the consistent refusion from the GQDs to the porous graphene sheet and then converted into GQDs/Gr. (b) TEM images of GQDs/Gr. (c) Top: the enlarged high-resolved HR-TEM image towards the GQDs lattice (left) and the FFT pattern (right). Bottom: the HAADF-STEM image of GQDs/Gr. (d) Top: the atomic resolved HR-TEM image of the graphene lattice (left) and the FFT pattern (right) to show the well-ordered honeycomb lattice structure with a lattice spacing of 0.21 nm. Bottom: the magnified HR-TEM images indicated a large area well-ordered graphene lattice.