Synthesis of N-doped carbon quantum dots from bio-waste lignin for selective irons detection and cellular imaging

Facile and controllable synthesis of graphene or graphene-like 2D nanosheets from plentiful and biocompatible materials still remains a great challenge. Herein, a bottom-up and controllable approach was firstly reported to transform earth-abundant lignosulfonate into graphene-like materials, in which lignosulfonate-based 2D nano sheets were fabricated via self-assembly in water/acetone dual solvent system, and then the nanosheets materials were transformed into graphene-like materials by carbonization. The physical properties of obtained lignosulfonate-based nanosheets were characterized, and the formation mechanism of these nanosheets was also elucidated. The thickness of the nanosheets was in the range of 5-20 nm depending on the concentration of lignosulfonate in water. Directed by pi - pi interactions and hydrogen bonds, the evolution of layered nano sheets seemed to experience from nano-sized rodlikes, a flake with defect holes, and smooth lignosulfonate-based nanosheets.