Molecular water oxidation catalysts based on first row transition metal complexes

Identifier:  TDX:3405

Handle: https://hdl.handle.net/20.500.11797/TDX3405

Authors:  Pelosin, Primavera

Abstract:
The objective of this thesis was to study the process of water oxidation through molecular catalysts based on first row transition metals. In chapter three was proved the importance of ligand design in the formation of rugged water oxidation catalysts (WOCs) based on copper. A tetra-amidate macrocycle ligand (TAML) was proved to stabilize the complex during catalysis through -delocalization of the generated positive charges. Further the macrocycle effect prevents the acidic demetallation of the catalyst, which was active also at neutral pH. In the fourth chapter was described an innovative procedure to form molecular anodes. The previously described TAML Cu-based WOC was modified with pyrene moieties, forming two regio-isomers with distinct electronic properties. Both the regio-isomers were anchored on the surface of indium tin oxide (ITO) electrodes through electropolymerization of the pyrene moieties in organic solvents. The anodes activity was tested through rotating ring disk electrode (RRDE) at pH 7.5, 9 and 10. The Chapter five is focused on the determination of the real nature of the catalysis. This study takes as an example a pentanuclear iron complex, considered a molecular WOC, which actually decomposes in presence of water and high potentials. The active species was confirmed to be hematite through several analysis as EDX, SEM, XPS and XAS.