Morphology-controllable synthesis of carbon nanomaterials directly on Al₂O₃ substrates, and their photoluminescence

By controlling the growth temperature, different categories of carbon nanomaterials (CNMs) such as carbon nanocoils (CNCs) and chain-like carbon nanospheres (CNSs) can be synthesized directly over Al₂O₃ substrate without using any transition-metal catalysts. It is proposed that the Al₂O₃ particles play a key role in the CNM growth, and the reaction temperature has a great impact on the morphology of the obtained CNMs. Furthermore, the photoluminescence studies indicate that the obtained CNCs and chain-like CNSs show different optical properties, which suggest that the optical properties of the obtained CNMs may be tuned by controlling their structures.