Structural Properties and Modifications in Synthesis Methods of Nanocomposites Carbon Quantum Dots– Graphene Quantum Dots– and Carbonized Polymer Dots–Based Technological Applications

Carbon-based quantum dots and their nanocomposites have sparked immense interest for researchers as sensors due to their attractive physico-chemical properties caused by edge effects and quantum confinement. In this chapter, we discuss the synthesis and application of nanocomposites of carbon quantum dots (CQDs), graphene quantum dots (GQDs) and carbonized polymer dots (CPDs). Different synthetic strategies for CQDs, GQDs and their nanocomposites are categorized as top-down and bottom-up approaches which include laser ablation, arc-discharge, chemical oxidation, ultrasonication, oxidative cleavage, microwave synthesis, thermal decomposition, solvothermal or hydrothermal method, stepwise organic synthesis, carbonization from small molecules or polymers, and impregnation. A comparison of methodologies is presented. The environmental application of nanocomposites of CQDs/GQDs and pristine quantum dots as sensors are presented in detail. Their applications envisage important domains dealing with the sensing of pollutant molecules. Recent advances and future perspective in the use of CQDs, GQDs and their nanocomposites as sensors are also explored. This chapter is devoted to the recent development in the synthesis of biomass- and chemical-derived C-dots as well as diverse functionalization of C-dots. In this chapter, we will provide an update on the latest research of carbon dots (CDs) on the synthetic routes, chemical modifications and optical properties. To this end, a new classification of CDs, CPDs, is summarized according to the analysis of structure and property features. Finally, a perspective of the future development of CDs is proposed with critical insights into facilitating their potential in various application fields.