On 14 January at 14:15 Sander Ratso will defend his doctoral thesis “Electrocatalysis of oxygen reduction on non-precious metal catalysts” for obtaining the degree of Doctor of Philosophy (in Chemistry).
Kaido Tammeveski (PhD), University of Tartu
Ivar Kruusenberg (PhD), National Institute of Chemical Physics and Biophysics
Juan Herranz (PhD), Paul Scherrer Institute (Switzerland)
Moving on from the carbon energy cycle that is destroying our environment and deteriorating living conditions is one of the priorities for humanity in the 21st century. However, nearly all of the energy used for transportation is still being produced by burning fossil fuels. Polymer electrolyte fuel cells (PEFC) have emerged as one of the pathways towards reducing the CO2 emissions from automotive applications and have already seen wide-scale use in fuel cell electric vehicles. The main remaining problems towards replacement of internal combustion engines by PEFCs are cost and durability. These issues stem from the slow oxygen reduction reaction (ORR), which takes place at the fuel cell cathode. So far, nearly all commercially available fuel cell systems have used platinum-based catalysts on the cathode to achieve this, but it has become apparent that the long-term activity and stability targets cannot be met by Pt-based materials while keeping costs low enough. This PhD thesis focuses on developing novel electrocatalysts for this reaction by rationally designing synthesis strategies for carbon nanomaterials. By using graphene, carbon nanotubes and carbide-derived carbon (CDC) and combining them with methods such as ball-milling and pyrolysis, new catalysts with atomically dispersed catalytic centres were developed. The dispersion of catalytic sites on such a level enhanced the activity of the catalyst material and thereby the power output of the fuel cell. Composite materials from carbon nanotubes and graphene or CDC were created to optimise the porous structure of the fuel cell electrode, which further raised the power density of the cell. New strategies for the optimisation of porosity in catalyst materials are also proposed in this thesis. In the end, multiple catalysts rivalling the activity of commercially used Pt/C materials are presented in this thesis, showing a great promise of non-precious metal catalysts for replacing Pt in automotive fuel cells.
Please note, the defence will be held in Microsoft Teams and Ravila 14a–1020.