Invesigation on Ir/Pt relationship in catalyst for water electrolysis

We have recently demonstrated that supporting IrOx on platinum coated titanium dioxide (IrOx-Pt-TiO2) with only a fraction of the PGM content (39 wt%) generates significantly higher activity (141%) towards the oxygen evolution reaction (OER) compared to commercial IrO2 catalysts. The operando spectroscopy performed at Ir LIII edge suggest that the oxidation state of Ir depends on Ir/Pt ratio. Underlying reason for this behaviour is revealed when observing the Ir-O bond, i.e. IrOx-Pt-TiO2 is shorter than analogous bonds in commercial unsupported IrO2. This suggests a strong interaction between Ir and Pt, with the possibility of a bimetallic specie forming. However, due to the proximity in energy of Ir and Pt LIII edge, it is not possible to confirm the presence of a intermetallic specie using EXAFS. Performing experiment at Ir and Pt k edge would be essential to establish the interaction between Ir and Pt, and confirm, or exclude, the presence of bimetallic species at the interface.