Novel carbon nanostructured based materials for energy related catalysis and electrochemical sensing of small biomolecules

The interest for carbon nanostructure-based hierarchical materials for electrochemical applications has been growing continuously in the last decade, from both an energy and sensing perspective. The use of carbon nanostructures is permitting to explore new opportunities in these research fields. Graphene, carbon nanotubes (CNTs) and single-walled carbon nanohorns (SWCNHs) can contribute to the design of revolutionary devices thanks to their special electronic and structural properties. This dissertation discusses the opportunity of carbon nanostructures integration into the assembly of hierarchical nanomaterials for electrochemical catalysis and electrochemical sensing applications. In particular, the major efforts have been focused in the use of SWCNHs due to their high purity, high conductivity, morphology and porosity, which can considerably aid to enhance performances. The hybrid materials have been synthetized using a hierarchical approach in order to achieve multicomposite-multifunctional nanomaterials able to orchestrate energy related processes such as O2 reduction reaction (ORR) and CO2 reduction reaction (CO2RR) or allow specific H2O2 sensing. In particular, two catalytic systems named t-Fe@MWCNTs (featuring Fe-filled functionalized multi-walled carbon nanotubes) and g-N-SWCNHs (featuring N-doped graphitized carbon nanohorns) have been employed for the O2 reduction reaction catalysis. On the other hand, ternary systems named Pd/TiO2@ox-SWCNHs (integrating oxidized SWCNHs, Pd and TiO2 in a precise hierarchical order) and NiCyclam@BMIM/p-SWCNHs (based on the heterogenization of molecular NiCyclam by embedding into pristine SWCNHs-supported ionic liquids) have been employed for the CO2 reduction catalysis. Finally, a catalyst based on the coating of oxidized SWCNHs with CeO2 (named ox-SWCNHs/CeO2) has been employed for the catalysis of H2O2 reduction exploited for H2O2 amperometric sensing. In all cases, the nanocarbon scaffold may play a multi-role, facilitating electron transfer steps, bringing up specific textural properties, and contributing to physically adsorb gaseous reactants. The result is an enhancement of the catalytic performance in terms of activity, selectivity and stability, which has been communicated through publication (or in the process of being published) in peer-reviewed journals.