Spectroscopic and Electrical Investigations into Chemical Interactions with Carbon Nanotubes

Decorating single-walled carbon nanotubes (SWNTs) with appropriate nanoparticle species or polymeric layers can induce unique chemical sensitivities and/or catalytic activities. The approach of decorating SWNTs with various chemically sensitive materials is advantageous because undecorated SWNTs are only inherently sensitive towards a limited range of molecules. Because they are electrically conductive and optically active, the enhanced chemical sensitivity of decorated SWNTs can be exploited for the development of chemical sensors or catalytic platforms. Of particular interest are the transduction mechanisms between the decoration layer and underlying SWNTs, which serves to signal the adsorption and/or reaction of particular molecular species at the SWNT surface.A variety of techniques have been employed to characterize the properties of decorated SWNTs towards the development of chemical sensors and catalytic platforms. In particular, a combination of optical spectroscopy, electrochemistry and solid-state electrical transport measurements provide real-time information into the charge transfer occurring at the decorated SWNT surface. This information provides valuable mechanistic insight into the electronic processes that dictate sensor response or catalyst efficiency.Using the above-mentioned techniques, we have demonstrated that charge transfer between SWNTs and adsorbing gaseous species creates simultaneous and complimentary changes in the optical spectroscopy and electrical transport properties of SWNTs. Moreover, our approach has allowed us to developed mechanistic descriptions of the interaction between adsorbing gas molecules and the decorated SWNT networks. The decorated SWNT system has potential applications in the field of chemical sensors and heterogeneous catalysis, and a fundamental understanding of the chemical processes may lead to better chemical sensors and/or catalysts