Sol-Gel Synthesis and Characterization of Co-Mo/Silica Catalysts for Single-Walled Carbon Nanotube Production

A series of silica-supported Co-Mo samples prepared by the sol-gel method has been compared as catalysts for the synthesis of single-walled carbon nanotubes (SWNT). The concentration ratio of ammonium hydroxide to the silica precursor tetraethoxysilane (TEOS) has an important effect on the resulting morphology of the silica support and, consequently, on the nature of the Co-Mo catalytic species. In turn, these morphology changes have significant effects on carbon yield, quality, and type of the single-walled carbon nanotubes obtained by the disproportionation of CO at 750 °C. In addition, a catalyst with an open microscale structure has been prepared by using carbon fibers as burnable sacrificial templates. This open structure results in several-fold enhanced carbon yield, while keeping the same nanotube quality as those obtained on conventional powder catalysts.