Non-covalent interactions of metal phthalocyanines with carbon nanotubes

Non-covalent functionalisation of carbon nanotubes with thermally stable macrocyclic molecules such as phthalocyanines are of great interest due to the synergistic combination of the properties of both components, which significantly increase their potential for technological application. Non-covalent functionalisation consisting of the deposition or adsorption of molecules on the surface of the carbon nanomaterial and has the advantage of preserving its graphitic or honeycomb structure, i.e., there is no formation of new chemical bonds. 

Therefore, the aim of this PhD thesis focused on the deposition of metal phthalocyanines on single-walled carbon nanotubes by sublimation and reflux methods. Phthalocyanines with rare earth metals were synthesised by the solvothermal method as they are not commercially available, in contrast with phthalocyanines that coordinate with transition metals. The nanotubes with the phthalocyanines were characterised by a set of analytical techniques and tested as electrocatalysts in water splitting. The non-covalent hybrids of nanotubes and macrocyclic molecules were modelled by molecular mechanics and density functional theory to understand the trends of the electronic properties of the hybrids, the possible structural changes of the phthalocyanines on the curved surface of a nanotube, the influence of the nature of the metal phthalocyanine, and the effects of chirality and defects of the nanotube.

Overall, it was shown that phthalocyanine adsorption can be realized on the surface of individual nanotubes and/or in agglomerates. Finally, a carbonaceous material obtained in the metal-free phthalocyanine purification process by sublimation was identified as nitrogen-doped carbon nanofibres from the oxidative decomposition of the macrocycle.

Dissertation: https://hdl.handle.net/11370/e8125fd2-5795-4638-b273-548ed0ef5258