Table 2.
Reaction parameters for CNT yield optimization using LA method
| Target material | Metal catalyst (%) | Inert gas | Pressure (Torr) | Furnace/oven temp. (°C) | Laser properties (laser vaporization pulse) | Major observation | Refs | |||
|---|---|---|---|---|---|---|---|---|---|---|
| Type | Oscillation wavelength (nm) | Heat (mJ/pulse) | Spot diameter (mm) | |||||||
| Graphite rod | – | Ar | 500 | 1200 900 200 |
Nd:YAG | 532 | 250 | 3 and 6 | • MWCNTs of length 300 nm are obtained with 4–24 layers • Yields depend on the following temp.: (a) At 1200 °C, defect-free MWCNTs are obtained; (b) At 900 °C, number of defects is increased; and (c) At 200 °C, no MWCNTs are synthesized • SWCNTs are not synthesized |
[150] |
| Metal-graphite rod | Co (1) Cu (0.6) Nb (0.6) Ni (0.6) Pt (0.2) Co:Ni (0.6/0.6) Co:Pt (0.6/0.2) Co: Cu (0.6/0.5) Ni/Pt (0.6/0.2) |
Ar | 500 | 1200 | Nd:YAG | 532 | 300 | 6–7 | • SWCNT are obtained with increasing temp up to 1200 °C • Yields obtained in an order of (a) Ni > Co > Pt, (b) Co/Ni > Co/Pt > Ni/Pt > Co/Cu • For Cu and Nb: no SWCNTs are secured |
[48] |
| Metal-graphite rod | Ni-Co (1.2) | Ar | 500 | 1200 | Nd:YAG | 532 (initial) | 250 (initial) | 5 (initial) | • >70% SWCNTs are secured with uniform diameter in the form of rope • One rope contains from 100 to 500 SWCNTs |
[49] |
| 1064 (final) | 300 (final) | 7 (final) | ||||||||
| Metal-graphite rod | Co/Ni (1) | Ar | 500 | 200 | Nd:YAG | 532 | 490 | 6 | • When the flow tube is 2.5 cm in diameter, Web-like SWCNT deposit is retained ↓ • When the tube dimension is increased by ~5 cm in diameter, 50 vol% of SWNCT is obtained ↓ • When 2.5 cm in diameter quartz tube coaxial and 5 cm tube extending are installed, 60 to 90 vol% SWCNT is acquired • Finally, 1 g/day SWCNTs are accomplished |
[160] |
| Metal-graphite rod | Ni (2) Co (2) Fe (2) Y (0.5) Ni/Y (4.2/1, 2/0.5, 1/0.25, 0.6/0.6, 0.5/0.1) Ni/Co (4.2/1, 2/2, 2/0.5, 1/0.25, 0.6/0.6, 0.5/0.13, 0.4/0.4) Ni/Fe (4.2/1, 2/0.5, 0.6/0.6) |
Ar | 400 | No Furnace is used | CO2
250 W |
– | – | – | • The soot contains large amounts of clean bundles of SWCNT (diameter 20 nm and lengths >1 μm) • SWCNTs of 80 vol% are synthesized at a rate of 50 mg/h • Ni/Y or Ni/Co showed rubbery web-like SWCNT soot |
[50] |
| Graphite + catalysts powder | Co Ni Y (2) |
Ar | 187–337 | – | Solar energy (2000 W) | – | – | – | • Parallel and bundled SWCNTs are obtained | [156] |
| Metal-graphite rod | Ni (2) Co (2) Y (0.5) Fe (2) Ni/Co (4.2/1, 2/ 2, 0.5/ 1, 0.6/0.6, 0.5/0.1) Ni/Y (4.2/1, 2/0.5, 1/0.25, 0.6/0.6, 0.5/0.1) Ni/Fe (4.2/1, 2/0.5, 0.6/0.6) Co/Y (2/0.5) Ni/La (2/0.5) |
Ar N2 He |
400 | – | CO2
12000 W |
– | – | 0.16 | • SWCNTs of diameter 1.4 nm are self-organized into a 20 nm bundle • Maximum yield was noticed with Ni/Y and Ni/Co catalysts • Cw-CO2 laser ablation is an easy and environment favorable method for the growth of high-quality SWCNT |
[158] |
| Metal-graphite rod | Co and Ni (2.5) | Ar N2 |
750 | 1100 °C | CO2
2100 W |
– | – | • 20–40% SWCNT with mean diameter of 1.2–1.3 nm are obtained | [190] | |
| Metal-graphite rod | Co–Ni (0.6) | Ar | 500 | 25–1150 | UV | 248 | – | – | • SWCNTs with 15–20 nm in diameter are secured • Yield is lower at lower temp • Repetition rate of 30 to 150 Hz leads to a higher yield and larger bundles |
[157] |
| Metal-graphite rod | Ni (1) Co (1) |
Ar N2 |
600 | 7726 | ND:YAG | 532 | 240 | – | • N2 atmosphere produces more bundled than those of Ar ambience | [191] |
| Metal-graphite rod | Co Ni (1.2) |
Ar | 750 | 999 1099 1199 1349 |
UV | 308 | 58 | – | • SWCNTs are formed with diameter 1.2∼1.7 nm and length >2 μm • The highest yields at 1349 °C |
[192] |
| Metal-graphite rod | Co Ni |
Ar | 500 | 1100 | UV | 248 | – | – | • SWCNT deposit of diameter 1.2 nm is secured | [193] |
| Metal-graphite rod | Co/Ni | Ar | 500 | 900 1000 1150 |
UV | 248 | – | – | • SWCNT of diameter 1.2 nm and length 10 μm aggregate into bundles containing 2–40 nanotubes • Optimal catalyst concentration of 1.2% synthesis high-quality SWCNT • Increasing the furnace temperature increases diameters |
[194] |
| Graphite rod | Fe2O3 (1–5) | Ar | 500 | – | ND:YAG | 532 | – | – | • Web-like MWCNT structures are obtained • Fe2O3 catalyst (1%) influenced the magnetic properties of the CNTs |
[195] |
| Graphite rod | – | Ar | 50 150 400 760 |
– | CO2
3.5 kW |
– | – | 2.6 | • Diameter of obtained MWCNT is in the range of 5–40 nm • Pressure at 760 Torr was more effective to get large fraction MWCNT |
[196] |
| Graphite rod | Fe/Al, Co/Al Ni/Al (1:1) | N2
H2 |
– | 800 | – | – | – | – | • Synthesized different nanostructures • Fe in the catalyst mix yielded only MWCNT • Samples containing Co or Ni led to a mixture of MWCNT and SWCNT |
[197] |