Nitrogen-doped graphene and graphene quantum dots: A review onsynthesis and applications in energy, sensors and environment

Doping of nitrogen is a promising strategy to modulate chemical, electronic, and structural functionalities of graphene (G)and graphene quantum dots (GQDs) for their outstanding properties in energy and environmental applications.This paper reviews various synthesis approaches of nitrogen-doped graphene (N-G) and nitrogen-doped graphene quantum dots (N-GQDs).;Thermal, ultrasonic, solvothermal, hydrothermal, and electron-beam methods have been applied to synthesize N-G and N-GQDs.These nitrogen-doped carbon materials are characterized to obtain their structural configurations in order to achieve better performance in their applications compared to only either graphene or graphene quantum dots.Both N-G and N-GQDs may be converted into functional materials by integrating with other compounds such as metal oxides/nitrides, polymers, and semiconductors.These functional materials demonstrate superior performance over N-G and N-GQDs materials.Examples of applications of N-G and N-GQDs include supercapacitors, batteries, sensors, fuel cells, solar cells, and photocatalyst.