Systematic study on the influence of chemical reactions towards understanding root growth of single wall carbon nanotubes

• Applicant: Professor Dr. Thomas Pichler
• Subject Area: Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2007 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 32521936

A key and perhaps the most pressing issue with carbon nanotubes (CNT) is a clear understanding of their growth mechanisms as this currently limits scaling up applications. The available catalysts in chemical vapour deposition (CVD) exceed those available in laser evaporation, where only four transition metals (Ni, Co, Pt and Rh) have been shown to catalyze SWCNT [1] on their own. Recently, we showed that metals outside the above mentioned four could be used to synthesize single wall CNT (SWCNT) when in the presence of O2 in laser evaporation [2] Moreover, laser ablation synthesis was successfully conducted at ambient temperature without additional heating. However, important questions on the use of add catalysts, such as O2 and their role remain. Within the context of this project we will conduct systematic studies on the growth of SWCNT in laser ablation, CVD, laser induced pyrolysis and water arc-discharge. A detailed analysis of the reaction parameters, such as catalysts precursors and products, add-catalysts, substrates and temperature will be conducted. These studies will use synthesis reactors in pure conditions and will also include the assembly of a CVD reactor coupled to an X-ray photoemission spectrometer and mass spectrometer allowing in situ-studies. This will enable key information on the oxidation states of the catalysts and precursor products to be obtained that will enable our understanding of SWCNT formation to be significantly improved. The samples will be characterized utilizing a vast array of tools such as Raman and optical absorption spectroscopy, and microscopy tools including transmission and scanning electron microscopes. These tools and others will provide full information on their electronic, optical and magnetic properties. Assessment of the characterization data and evaluation of the synthesis parameters will provide direction on practical low temperature synthesis of SWCNT. More importantly the project will enable crucial growth mechanisms, such as catalysts/add-catalyst/substrate coupling processes, to be determined and provide invaluable knowledge that will close, if not bridge the gap, that currently prevents controlled synthesis of SWCNT of a chosen diameter and chirality which determines all the physical properties.

• DFG Programme: Research Grants