Observations of DWNT before and after purification

Carbon nanotubes (CNT) require purification after manufacture, due to the significant amounts of catalyst, oxide, and other impurities contained. The Scanning Probe Microscope (SPM) is a useful tool for evaluation of the purification status by providing direct observations of the CNT and non-CNT residues before and after purification.

Fig.1 shows unpurified double-walled carbon nanotubes (DWNT) after manufacture. Most of the DWNT cannot be recognized as CNT in shape. However, in the image of purified DWNT in Fig.2, most of the DWNT can be clearly identified. Observation of bundled and dispersed nanotubes is also possible.