From Advanced Materials to Sustainable MetalFree Catalysts via Tailored Chemical Decorations of Carbon Nanostructures

In the first part of the thesis an original, efficient and versatile approach to the convenient and facile functionalization of carbon nanotubes capable of imparting multimodality to these fundamental nanostructures, is described. In particular, the strategy developed takes advantage from the well established Cu-mediated acetyleneazide coupling (CuAAC) reaction applied to phenylazido-functionalized CNTs for their convenient homo-/hetero-decoration using different organic/organometallic frameworks bearing terminal acetylene pendant arms. The mild reaction conditions required, the high chemoselectivity and functional group tolerance of the CuAAC approach make the 14 protocol highly versatile for CNT single step multidecoration, avoiding those drawbacks resulting from the application of different and subsequent organic functionalization methods. The protocol has been properly applied for the synthesis of optically traceable nanocarriers through the smart and easy hetero-decoration of CNTs with a fluorescent probe and a new bifunctional linker designed for the facile and controllable conjugation of complex (bio)molecules. The CuAAC protocol has been conveniently extended from monodimensional carbon nanomaterials to other complex structures such as Metal Organic Frameworks (MOFs), imparting multimodality to these porous, crystalline 3D organometallic coordination polymers and demonstrating the general applicability of the developed method. In the second part of the work, an energy- and atom-saving process to the production of tailored N-doped and catalytically active metal-free carbon nanostructures, has been set up. The N-decoration of multiwalled carbon nanotubes occurs via chemical functionalization under mild reaction conditions and generates effective catalysts for the oxygen reduction reaction in alkaline medium. Our ex-situ approach allows a precise control of the N-containing groups representing a unique tool for shedding light on the complex structure-reactivity relationship of N-doped carbon nanomaterials in ORR and a unique model for an in-depth understanding of the underlying reduction mechanism.