Schematics of single-walled carbon nanotubes synthesis by chemical vapor deposition process. (a) At first, cobalt-acetate ethanol solution (0.2 wt% and 0.4 wt%) is prepared. (b) 50 nm and 200 nm silica nanoparticles were added to Co-acetate ethanol solution. (c) Ultrasonication of the solution for 90 minutes in bath-type sonicator. Cobalt particles gather together making clusters on the surface of silica nanoparticles. (d) Previous sample is dropped on Si wafer and dried. This wafer goes through the CVD process.