Dissertation
Poprhyrin-based metal-organic frameworks for the electrochemical oxygen reduction reaction
Hydrogen peroxide (H2O2) is an important bulk chemical that is used in various industrial processes. More than 95% of the H2O2 used in industry is made via the anthraquinone process during which a large amount of energy is going to waste.
- Author
- D. Rademaker
- Date
- 14 January 2025
- Links
- Thesis in Leiden Repository
To find a more sustainable synthesis route, attention has been drawn to the on-site generation of H2O2 via the electrochemical two-electron oxygen reduction reaction (ORR). Especially cobalt-based catalysts employed with macrocyclic N4–ligands were found to be active for the ORR toward H2O2 formation. When such catalysts are used in solution, it was found that self-aggregation promotes the four-electron ORR toward water formation by opening up a bimolecular pathway for the ORR. A more defined method of heterogenization of porphyrin catalysts to prevent bimolecular interactions might be found in metal-organic frameworks (MOFs). Electrocatalysis in metal-organic frameworks is expected to be an interplay between the diffusion of charges, the intrinsic catalytic rate, and the mass-transport of substrate through the pores in organic media. Whether these descriptors are still relevant for electrocatalysis with MOFs in aqueous solutions has not been investigated thoroughly. This thesis sets out to investigate the activity, selectivity, and stability of porphyrin-based MOFs during the electrochemical ORR in aqueous solutions. Moreover, the effect of external factors such as the dropcasting ink composition, the electrolyte nature, and the electrolyte concentration are investigated to better understand the factors that drive the ORR in MOFs in aqueous solution.