Formation of Y-junction carbon nanotubes by catalytic CVD of methane

Y-junction carbon nanotubes were grown by catalytic CVD of methane at 700 ∘C on NiO–CuO–MoO(7:2:1) (w/w/w)/SiO2 catalyst. For comparison, NiO–CuO(8:2) (w/w)/SiO2 and NiO–MoO(8:2) (w/w)/SiO2 catalysts were tested for carbon nanotube formation. TEM analysis indicates that no Y-junction structures were formed with the latter two catalysts. This finding elucidates why the addition of a small amount of MoO to NiO–CuO/SiO2 catalyst is crucial for enhancing the formation of Y-junction carbon nanotubes.