| Top-down | Hydrothermal synthesis;
solvothermal synthesis;
acidic oxidation;
electrochemical exfoliation | Large output;
simple operation. | Irregularly size and shape;
lots of oxygen-containing functional
groups left on the GQDs surface;
strong reductants are needed; numerous
defects. | [11-19] |
| Oxidation cutting of CF | Simple operation;
large output;
relatively cheap raw materials. | Too many oxygen-containing functional
groups;
low quantum yield(QY). | [21] |
| Ultrasonic exfoliation | Simple operation;
no reduction process; fewer surface
defects and more stable electronic
properties. | Depending on the quality of carbon fiber;
special equipments are needed. | [22] |
| Electron beam lithography | Precise control on both size and
shape of resultant GQDs | Complex operation; expensive equipments;
extremely low output. | [23] |
| Bottom-up | Solution chemical
approaches | Well-defined monodispersed
structures;
easy control of both size and
shape; high purity. | Low-output;
difficulty to prevent aggregation. | [21],
[24-26] |
Carbonization of
organic molecules | Well-defined monodispersed
structures;
high QY;
simple operation | Low-output. | [24],
[27-28] |
| Cage-opening of C60 | Well-defined monodispersed
structures;
precise control on both size
and shape; high QY. | Strict reaction conditions;
very high heating temperature; expensive
raw materials;
low-output. | [24] |