Combinatorial Synthesis of Functionalised Carbon Nanotubes as Building Blocks of Electronic Nanostructures

V. ORTIZ; J. BALACH; D. F. ACEVEDO; M.C. MIRAS; C. A. BARBERO

Viña del Mar, Chile

Workshop; Frontiers In Materials research III”. International Workshop; 2006

Carbon nanotubes have attracted many scientist in the field of physics, chemistry and material science due to their unique properties as well as their promise in the area of material chemistry.[1,2] One promising application of multiple wall carbon nanotube (MWNT) is their use in chemical sensors and nanoscale electronic device. Such potential application would greatly benefit from the ability of MWNT to promote the electron transfer reaction of important biomolecules, including cytochrome c,[3] NADH,[4] catecholamine neurotransmitters.[5] To build electrochemical devices, the nanotubes should be deposited onto conventional electrode materials (glassy carbon, ITO), from nanotube solutions or stable dispersions. The major barrier to produce useful devices is the solubility of the MWNT. It is known that it is possible to improve solubilization to the MWNT using two different synthetic methods. One method involves noncovalent modification by Gomberg reaction of the aromatic rings of the MWNT with diazonium salts.[6] The other imply the non-covalent wrapping of soluble conductive polymers. In the later method we use combinatorially modified polyanilines [7] where a wide variety of polymers is available. The MWNTs were functionalized and their solubility in different solvents were tested. Thin films of MWNTs were then deposited by evaporation of the solvent on ITO or glassy carbon electrodes. The electrochemical response hydrogen peroxide, a relevant redox analyte produced by various enzymes, is then tested. The products of the reaction were identified by Differential Electrochemical Mass Spectroscopy (DEMS). Since the functionalized MWNTs bear charge, the self assembly of MWNT/polyelectrolyte multilayers was also tried. It was found that it is possible to assemble multilayers where the faradaic current of H2O2 oxidation increase with the number of layers, indicating that the layers are connected and active.