Nanowires better than nanotubes?
The limitations of using nanotubes have prompted those in the field to seek out inorganic alternatives. One of these is found in nanowires comprising molybdenum, sulphur and iodine (MoSI), with WS2 nanotubes showing the greatest potential. Among their most attractive properties are easy fabrication that can be readily scaled up, uniformity in diameters and electronic type, and functional properties very similar to carbon nanotubes. Being a new class of materials, however, they have yet to be extensively studied for practical and technological applications. The 'Processing and electron probing inorganic nanostructures for emerging nanotechnologies' (Pepinen) project aimed to highlight related issues, connecting their ongoing nanotech development with effective use in multifunctional applications. The overarching objective was to investigate the potential of novel nanotubes and nanowires as future nanoscale components. The EU-funded project conducted a complete structural study of Mo6S4.5I4.5 nanowires using a combination of specific microscopy and spectroscopy techniques. Results revealed that these nanowires have a highly defective, multi-crystallographic nature characterised by a complete absence of long-range order. This outcome was just the opposite in the case of results obtained for the more ordered Mo6S3I6 nanowires. Determining the structure of the Mo6S4.5I4.5 nanowires allowed researchers to carry out various calculations to predict the electronic behaviour of both single nanowires and nanowire bundles. Other experiments facilitated elucidation of processing issues for Mo6S2I8 nanowires, and the development of methodologies for their dispersion and de-bundling. Pepinen's focus on essential and high-quality basic and fundamental research contributed to the state of European excellence and competitiveness in the study of inorganic alternatives to carbon nanotubes.
