Developing improved catalysts for
the oxygen evolution reaction
(OER) is key to the advancement of a number of renewable energy technologies,
including solar fuels production and metal air batteries. In this
study, we employ electrochemical methods and synchrotron techniques
to systematically investigate interactions between metal oxides and
noble metals that lead to enhanced OER catalysis for water oxidation.
In particular, we synthesize porous MnO<sub><i>x</i></sub> films together with nanoparticles of Au, Pd, Pt, or Ag and observe
significant improvement in activity for the combined catalysts. Soft
X-ray absorption spectroscopy (XAS) shows that increased activity
correlates with increased Mn oxidation states to 4+ under OER conditions
compared to bare MnO<sub><i>x</i></sub>, which exhibits
minimal OER current and remains in a 3+ oxidation state. Thickness
studies of bare MnO<sub><i>x</i></sub> films and of MnO<sub><i>x</i></sub> films deposited on Au nanoparticles reveal
trends suggesting that the enhancement in activity arises from interfacial
sites between Au and MnO<sub><i>x</i></sub>
