Synthesis, purification and opening of short cup-stacked carbon nanotubes

A simple method is demonstrated to synthesize high-quality cup-stacked carbon nanotubes (CSCNTs) with short length. The as-synthesized CSCNTs are 0.2-3.2 microm in length, even shorter than the ball-milled long CSCNTs (approximately 7 microm). These CSCNTs have a diameter of 80-120 nm and a hollow channel of 60-100 nm along the nanotube axis. Moreover, a simple purification method is developed to remove iron particles and obtain short CSCNTs with two open ends. Such CSCNTs are very easily suspended in distilled water and tetrahydrofuran, which makes such material greatly promising as a candidate in many applications such as heterogeneous catalysis and photoelectrochemical cell.