Low Ti Additions to Stabilize Ru-Ir Electrocatalysts for the Oxygen Evolution Reaction

Anodic oxygen evolution reaction (OER) challenges large scale application of proton exchange membrane water electrolyzers (PEMWE) due to sluggish kinetics, high overpotential and extremely corrosive environment. While Ir oxides currently provide the best balance between activity and stability, the scarcity of Ir and corresponding high market price lead to poor cost-benefit factors. Mixing Ir with more stable non-precious Ti reduces the noble metal loading and may implicate stabilization, while addition of more catalytically active Ru ensures a high reaction rate. Here, we examine the activity-stability behavior of Ru-Ir-Ti thin film material libraries with low Ti-content under the OER conditions. The high sensitivity to the dissolution of the individual alloy components was achieved by using online and off-line inductively coupled plasma mass spectrometry (ICP-MS) analysis. Our data reveal that even low Ti additions improve the stability of Ru-Ir catalysts without sacrificing activity. In particular, 5 at. % of Ti enable stability increase of Ir in the Ru-Ir catalyst by a factor of 3. Moreover, this catalyst exhibits higher activity compared to the Ti-free Ru-Ir alloys with similar Ir content. Observed activity-stability trends are discussed in light of X-ray photoelectron spectroscopy data. Ru-Ir-Ti Electrocatalysts for the oxygen evolution reaction: We examined activity and stability behaviour of numerous Ru-Ir-Ti alloy compositions with high sensitivity to the dissolution of the individual metal components. Obtained results show a trend of increasing stability for Ir and Ru with growing Ti amount. Ti additions of 5 at. % provide an increase in Ir stability by a factor of about 3 compared to Ti free Ru-Ir alloys.image