Role of precursor microstructure in the development of graphene quantum dots from biomass

Renewable, green and cheap biomass could meet the urgent need of cost-effective graphene quantum dots (GQDs) if microstructure and quality can be precisely controlled. Herein, for the first time, we investigate the effect of precursor microstructure on the growth of GQDs from biomass. A novel process is developed which combines carbonisation, oxidation and nitration with controlled hydrothermal fragmentation to form GQDs. The results indicate that aromatic structure of carbon material as a precursor is the key to obtain high-quality GQDs. The as-prepared GQDs possess a 3-9 layer graphene structure with an average size of 11.6 +/- 1.8 nm and exhibit a moderate quantum yield of 17.5%. These GQDs are used to develop a highly selective and sensitive sensor to detect ferric ions with a detection limit as low as 26 +/- 0.4 nM. This study highlights the development of high quality GQDs from biomass for real-world sensing, photocatalytic and biomedical applications.