Platinum–titanium alloy catalysts on a Magnéli-phase titanium oxide support for improved durability in Polymer Electrolyte Fuel Cells

The robustness of the cathode catalysts used in polymer electrolyte fuel cells (PEFCs) is one of the major factors that determines their durability. In this work, a new class of corrosion-resistant catalyst, Pt–Ti alloy nanoparticles deposited on nano-sized sub-stoichiometric titanium oxide (TiOx), was prepared, and the durability of a Pt–Ti/TiOx cathode under conditions of fuel cell operation was evaluated. Cell performance under a constant current density for >900 h was examined to demonstrate the practical stability of the Pt–Ti/TiOx MEA under PEFC operating conditions. To investigate the effect of high potentials on cathode catalyst activity, a potential cycling test between 1.0 V and 1.5 V vs. a hydrogen anode was applied to the MEA. The results indicated that the electrochemical surface area (ECA) of the Pt–Ti/TiOx MEA is much more stable than that of a conventional Pt/XC72 MEA, and there is almost no loss of ECA even after 10,000 potential cycles. In addition, there was almost no change in the internal resistance of the MEA. TEM analyses of the potential-cycled MEA clearly revealed the excellent stability of Pt nanoparticles supported on TiOx particles.

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► Corrosion-resistant Pt–Ti alloy/sub-stoichiometric Ti oxide catalysts were prepared.
► Pt–Ti/TiOx MEA shows a mass activity comparable to that of conventional Pt/XC72.
► Performance loss of Pt–Ti/TiOx MEA was very limited even after potential cycling to 1.5 V.
► Superior stability of Pt–Ti/TiOx catalyst under high potential is due to the robustness of the TiOx support.