Chapter 6
The benecial interaction
between Au and MnOx
The search for new electrocatalysts for the oxygen evolution reaction has long
involved mixed materials beneting from interactions rather than the addition
of their individual properties. However, with the scaling relations in place it appears
that further activity enhancements are highly unlikely from most standard
surface structures. Even with close to optimal binding energies to intermediates,
an overpotential of around 300 mV seems necessary to drive the oxygen
evolution reaction at appreciable current densities. Constructing surfaces for
which the scaling relations do not hold is therefore a critical challenge. In chapter
2, section 2.5.2, a few examples of benecial combinations of materials were
highlighted. In this chapter the focus will be on the interaction between Au and
MnOx, which results in large activity improvements. First, a conceptual model
based on binding energies will be introduced, see appended paper II. Then an
experimental approach will be presented, where the objective is a comprehensive
characterization of mixed Mn-Au thin lms. The experimental results obtained
from this study constitute the basis for the appended paper IV.
6.1 Theoretical model of Au-MnOx interaction
As mentioned in chapter 2, scaling relations express the linear relationship regarding
binding energies for alike adsorbates. Specically for the oxygen evolution
reaction, *O, *OH and *OOH bind in a similar fashion to most surfaces and
changing the binding strength to one of them necessarily changes the binding