Continuous hydrothermal flow synthesis of graphene quantum dots

Green fluorescent graphene quantum dots (GQD) have been synthesized via hydrothermal fragmentation using a continuous hydrothermal flow synthesis (CHFS) process as a single, rapid and environmentally benign method. This is in the presence of p-phosphonic acid calix[4]arene which enhances the optical properties of the graphene quantum dots through surface functionalization, with photoluminescence quantum yields of up to 4.5%. Potential environmental impact of a lab-scale supercritical CHFS process compared with that of conventional batch processing of GQDs has been assessed using the method of the International Reference Life Cycle Data System (ILCD)