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Processing and Electron Probing Inorganic Nanostructures for Emerging Nanotechnologies

Final Report Summary - PEPINEN (Processing and electron probing inorganic nanostructures for emerging nanotechnologies)

The aim of this research project was to unlock the potential of novel binary and ternary transition metal chalcogenides nanotubes and nanowires as future nanoscale components. As with all materials, liquid-phase dispersion and processing and determination of the crystallographic structure, with particular interest to the structure of the defects within the material, is a crucial first step to allow the materials' properties to be more fully understood.

In fact in spite of the large range of applications up to now proposed for both MoSI nanowires and WS2 nanotubes, a number of points still needed to be addressed in order to feasibly consider them for practical and technological applications. The project has aimed to intimately unlock these issues, connecting with the ongoing development in nanotechnology for their multifunctional applications in the near future. This proposal as given an important and unique contribution to the field, greatly enhancing the EU scientific excellence. Moreover, the realisation of this project as allowed Dr Nicolosi to approach her first appointment with full technical and managerial responsibility. She has been able to initiate, organise, coordinate, execute and interpret her own research and achieve the stated scientific goals. This has improved her discipline and her professional maturity and has constituted her fist step as a semi-independent scientist. Dr Nicolosi has resigned from her position of Marie Curie Research Fellow, effective 1 March 2009 (one year before the actual stated termination date). The withdrawal from the fellowship will allow me to take up a new academic position as Royal Academy of Engineering/EPRSC Senior Research Fellow at the University of Oxford, Department of Materials. The Marie Curie Fellowship was timely in Dr Nicolosi's career, having encouraged her professional growth and allowed development of the expertise necessary for her next step as an advanced independent researcher.

Scientific results:
- A complete structural study on Mo6S4.5I4.5 nanowires has been performed using a combination of aberration corrected HRTEM and HAADF STEM microscopy and EELS and EDX spectroscopy. Mo6S4.5I4.5 nanowires revealed a highly defective, multi-crystallographic nature with complete absence of long range order. This is in clear contrast with the results obtained for the much more ordered Mo6S3I6 nanowires. A paper is currently in preparation and will be shortly submitted to an internationally regarded peer-reviewed journal.
- Having determined the structure of Mo6S4.5I4.5 nanowires had allowed to proceed with density functional theory (DFT) calculations in order to predict the electronic behaviour of both single nanowires and nanowire bundles.
- Mo6S9-xIx nanowire structural defects have been investigated with in-situ electron microscopy techniques. Being ahead of time on the other project tasks has allowed Dr Nicolosi to tackle this topic before the expected time. In spite of being a task designed for the second year of the project, Dr Nicolosi is already in possess of exciting preliminary electron microscopy results already after 12 months into the project. These results suggest dramatic changes in the electronic band structure of the material in the presence of structural defects.
- Solution-based processing issues have been unlocked for Mo6S2I8 nanowires. Methodologies have been developed for the dispersion and de-bundling of Mo6S2I8 nanowires. A paper is currently in preparation and will be shortly submitted to an internationally regarded peer-reviewed journal.

Contribution to European excellence and European competitiveness:
This project has accomplished extremely important goals:
- It has recruited, prepared and trained a young and resourceful researcher. This is an extremely important need to strengthen the European competitiveness.
- It has focussed on essential and high-quality basic and fundamental research, which is the key driver of innovation.