Optimization of carbon nanotube synthesis from porous anodic Al–Fe–Al templates

A parametric study of carbon nanotube (CNT) synthesis from catalytically active porous anodic Al–Fe–Al multilayer templates was conducted with respect to pore aspect ratio, Fe layer thickness, CNT synthesis temperature, and pre-anodization thermal annealing. Performance metrics included CNT catalytic activity and the pore wall integrity at the Al–Fe–Al interface. The observed CNT density was a strong function of pore diameter, synthesis temperature and pre-anodization annealing of the catalyst film. Vertical pore wall integrity at the Al–Fe–Al interface was optimized by selection of pre-anodization annealing conditions, with interfacial void formation observed in the absence of this technique. Based on CNT growth rates, an activation energy of 0.52 eV was observed for CNT synthesis for all film structures, regardless of pore aspect ratio. The optimization of templated CNT synthesis is expected to assist in the development of high-density vertically oriented CNT-based devices.