Influence of purity and metallicity on gas sensing applications of single walled carbon nanotubes and their heteroatomic doping at low doping levels

Rosa Georgina Ruiz Soria
2013 unpublished
Single-walled carbon nanotubes are one of the most interesting and fascinating materials, which unique characteristics have transformed them into excellent candidates for a great variety of applications. The research related to single-walled carbon nanotubes has reached a fairly mature status regarding the production of clean and sorted material. This has allowed understanding their physical properties to a certain extent. However, the fast development of the field of applications started a
more » ... time before the production of ultra-pure material was achieved, i.e. material without remaining catalytic by-products or even species of dis- similar metallic character. This means that several types of established applications need to be rethought. The specific focus of this PhD thesis is the understanding of the electronic properties of single-walled carbon nanotubes and their changes upon functionalization in different manners. Substitutional functionalization has been investigated at ultra-low amounts of doping levels in purified nanotube-material. This was done using photoemission and X-ray absorption spectroscopy, which have allowed clearly identifying the bonding environments present in such doped-tubes unambiguously. On the other hand, I have studied the on-wall functionalization of the tubes using them as sensing objects by analyzing the changes in their electric response while interacting with gas molecules. In this context, most studies deal with the use of nanotube-material that is either highly defective or non-purified, It has often been proposed that the intrinsic defective sites and those created during the tube processing are responsible for the changes in their electronic response. I address this problem by studying either the physisorption or chemisorption of gas molecules from a spectroscopy point of view. The results obtained in this thesis aim at paving the way toward controlled sensing using carbon nanotubes ruling out the effect of impurities. It aims at revealing aspects that can be applied to dif [...]
doi:10.25365/thesis.30496 fatcat:jghobrbd5vh5borkmziwcfhjvi