Towards Highly Active and Stable Oxygen Electrocatalysts

Claudie Roy

Research output: Book/ReportPh.D. thesis

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This PhD thesis presents work on the development of electrocatalysts for oxygen evolution and reduction reactions. The oxygen evolution reaction (OER) is a bottleneck in the large-scale development of electrolyzers, which are promising technologies for energy storage in hydrogen bond. Polymer electrolyte membrane (PEM) electrolyzers rely on scarce and expensive materials like RuOx-based catalysts to achieve high efficiency. However, RuOis also unstable under OER conditions. Part of this work was to study the catalytic activity and stability of oriented thin lms of RuO2 with the (111), (001), and (101) orientations, and compare it to RuO2 (110) single-crystal and commercial particles. The catalytic activity was measured from stability tests performed in 0.05 M H2SO4 and coupled with inductively coupled plasma mass spectrometry to measure Ru dissolution. 
The second part of this thesis focuses on the better understanding of NiFeOxHy catalysts for the OER in alkaline electrolyte. NiFeOxHy as OER catalyst has been used in the industry for decades, but several open questions remain regarding the reasons for its very high catalytic activity. Using a model system of mass-selected NiFeOxHy nanoparticles, we addressed two main questions i) the impact of size effect and ii) the role of bulk activity on the oxygen evolution.
The reverse reaction, the oxygen reduction reaction (ORR), was also studied. ORR is the limiting reaction in hydrogen fuel cell technologies, which allow for the conversion of hydrogen back to electricity. The third and last part of this work focuses on the synthesis of Pt-rare-earth alloys on a gram scale. We investigated the alkalide and cyanide reduction, and the high thermal synthesis methods.
Original languageEnglish
PublisherDepartment of Physics, Technical University of Denmark
Number of pages277
Publication statusPublished - 2018

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