Solar synthesis of single-walled carbon nanotubes at medium scale

Single-walled carbon nanotubes were synthesized in gram quantities with a 50 kW solar reactor. Vaporization rate was in the range 6–15 g/h and two samples were collected for each run. The structure of the products was studied by SEM, TEM and Raman spectroscopy as a function of the buffer gas (helium or argon), the target length and the collected location. Good quality samples containing 1.2–1.6 nm diameter SWNTs were produced with helium at 450 hPa, 8 Nm3/h and a 15 cm target length using 2 at.% Ni and 2 at.% Co as catalyst. The material quality increased with the target length in helium. On the contrary, poor quality product was obtained whatever the target length in argon. TGA analysis showed that the best product purity was at least 35 wt%.