Inoganic Nanowires
One of the problems with carbon nanotubes is that they are produced as both metals and semiconductors a range of bandgaps. Efficient, large-scale separation by type has proved elusive. However, nanotubes, nanorods and nanowires can also be produced from inorganic materials by a range of techniques. It is possible to produce metallic, semiconducting or insulating nanorods, even to specify bandgap to some degree!
We are in the process of studying nanorods made of molybdenum sulphur and iodine (MoSI) as metallic nanowires (see papers 53 and 60), semiconducting CdSe and CdS nanorods and insulating TiO2 nanorods. This work has both basic and applied facets. For example we have used HRTEM and STEM to discover the structure of the MoSI nanowire unit cell as well as how they pack together as van der Waals crystals. Applied research involves the study of these materials as conductive fillers.
Figure 9 Scanning TEM images of bundles of MoSI nanowires
Figure 10 Structure of MoSI nanowires as determined by microscopy.
We are studying photoinduced charge transfer between CdS nanorods and conjugated polymers with the aim of developing composite solar cells. Finally, by functionalizing TiO2 nanorods we have been able to disperse them in polymer solutions allowing us to fabricate reinforced, insulating composite films.