Efficient formation of iron nanoparticle catalysts on silicon oxide by hydroxylamine for carbon nanotube synthesis and electronics

Iron containing nanoparticles are found to spontaneously form on hydroxylated SiO2 substrates when immersed in a freshly mixed aqueous solution of FeCl3 and hydroxylamine. Upon calcination, a submonolayer of uniformly distributed iron oxide nanoparticles can be derived and used to catalyze the growth of single-walled carbon nanotubes by chemical vapor deposition. This simple method affords clean single-walled nanotube films on SiO2. The solution phase catalyst deposition approach allows for submicron scale catalyst patterning. Patterned growth of nanotubes with this catalyst retains high degrees of surface cleanliness and leads to arrays of nanotube electronic devices including field effect transistors. The population of hydroxyl groups on SiO2, reaction time, and pH of the solutions are found to be important to the deposition of nanoparticles through a surface-mediated hydroxylamine/FeCl3 chemistry.