iv
than 40 %, while the activity decreased with 10 %.
Finally, for MnO2 to be useful as an OER catalyst in PEM cells, the activity
should be improved. Mixtures of manganese oxide and gold have been reported
to exhibit activity enhancements and, hence, a nal part of the thesis focus on
this system. Mixed thin lms were prepared, which exhibited ve times higher
current density compared to pure Mn oxides. X-ray Diraction measurements
indicated that Au domains of approximately 3 nm were important for this enhancement.
Furthermore, from an in-situ X-ray Absorption Spectroscopy study
it was found that Mn oxidises at a more cathodic potential when Au is nearby.
This experimental study serves as a starting point for understanding the bene-
cial interaction between gold and manganese oxides.
