In the last decades, the interest to adopt new sustainable industrial processes and to find new eco-friendly ways to convert and store energy with a lower impact on the environment is growing due to the devastating consequences of our actions. In this Ph.D. project are investigated new sustainable catalysts based on carbon nanostructures for photocatalytic and electrocatalytic applications. In the first part of this thesis, 3 electrocatalyst for the oxygen reduction reaction (ORR) are proposed: Raspberry-like FeOx nanoparticles were covered with graphitized polydopamine (SNC@PDA500). Subsequently the inorganic core was removed in order to form an hollow N,O co-doped carbon nanoshell (g-PDA500). The elimination of the inorganic core leaves low doses of Fe that migrates on the surface of the carbon nanoshell and form ultrasmall FeOx nanoparticles when g-PDA500 is treated at 700 °C (g-PDA700), following an ex-solution process. SNC@PDA500 and g-PDA500 are active for the O2-to-H2O process (that finds application in fuel cells) while g-PDA700 is active for the O2-to-H2O2 process (that could be relevant as a sustainable alternative to the traditional H2O2 industrial production).
In the second part graphitic carbon-based nanomaterials are explored for light-mediated perfluoroalkylation reaction. In particular, the structure/activity relationship was studied in order to determine relevant mechanistic aspects. Graphitic carbon nitride (g-CN) was prepared by conventional thermal polymerization of melamine. Subsequently, post-synthetic structural modifications of g-CN were performed applying 3 different protocols to obtain amorphous carbon nitride (am-CN), reduced carbon nitride (red-CN) and oxidized carbon nitride (ox-CN). am-CN revealed high performance for the perfluorobutylation of 1,3,5 trimethoxy-benzene (model reaction) and showed high performances for 2 classes of reactions: homolytic aromatic substitution (HAS) and atom transfer radical addition (ATRA). Subsequently, the amorphization treatment was investigated: 4 superamorphed carbon nitrides (SACNs) were proposed: 4h-SACN, 6h-SACN, d-SACN and t-SACN. Similarly, the oxidation treatment was explored preparing 3 different oxidized carbon nitrides (OCNs): 2M-OCN, 8M-OCN and OW-OCN.
In the last part, 3 different CN-based nanomaterials are prepared: 1) mesoporous graphitic carbon nitride (mpg-CN) using an eco-friendly protocol that involves CaCO3 as hard template, 2) poly heptazine imides (PHIs). The proposed PHIs are prepared following 2 approaches: using a eutectic mixture of LiCl and KCl (PHIK) and using both NaOH and KOH (PHIK-Na).
