Reducing the cathode degradation in proton exchange membrane fuel cells during start-up and shut-down events (where the anode is filled with H 2 and air) is crucial for its widespread automotive implementation. The use of selective catalysts for the hydrogen oxidation reaction (HOR) that sparingly reduce oxygen on the anode could significantly reduce the carbon corrosion on the cathode. Herein, we report a novel system of carbon supported Pt/TiO x catalysts that combines the unique properties of a strong metal−support interaction (SMSI) with the known advantages of a carbon support. Highresolution transmission electron microscopy of the selective catalyst shows the encapsulation of the Pt nanoparticles (NPs) by a TiO x layer resulting from the SMSI. Rotating disk electrode experiments confirmed that Pt oxidation and oxygen reduction are hindered due to the TiO x layer. Furthermore, a high HOR activity that is retained even at high potentials proved the superior HOR selectivity of the catalyst.

The formation of strong metal support interactions (SMSI) is known for many metal/metal oxide systems and its consequences are well established in the field of heterogeneous catalysis, but this knowledge has only been recently transferred to the field of electrocatalysis. In this study, Pt was deposited via atomic layer deposition (ALD) onto TiO2−Y, which allowed a good control of the particle size through the number of ALD cycles. During the ALD process, a thin-film of reduced titania is formed on the Pt surface, which leads to SMSI effects. With increasing Pt particle size, the fraction of the titania-covered Pt surface decreases. As a result, the extent of platinum oxide formation in cyclic voltammetry (CV) measurements scales with the size of the Pt particles. The influence of these thin titanium oxide films, which cover the Pt surface, on the catalytic behavior with respect to oxygen reduction reaction (ORR), hydrogen oxidation reaction (HOR), CO oxidation and oxygen evolution reaction (OER) is investigated by using an RDE setup. The covering TiOX thin-films reduce the ability to catalyze ORR, OER and CO oxidation, while it does not influence the HOR and Pt H-UPD formation. These findings indicate that proton and hydrogen transport are possible through the thin TiOX film, while oxygenated species suffer from transport limitations through the thin-film. Due to this selective permeability, these materials are able to oxidize hydrogen well beyond 1.2 VRHE.