Corrosion-Resistant PEMFC Cathode Catalysts Based on a Magneli-Phase Titanium Oxide Support Synthesized by Pulsed UV Laser Irradiation

Nano-sized sub-stoichiometric titanium oxide (TiOx), synthesized by pulsed UV laser irradiation of TiO 2 , was used as a catalyst support material for a PEMFC cathode, and its catalytic activity for the oxygen reduction reaction (ORR) and stability against high potentials >1.0 V were examined by comparison to a conventional Pt/C catalyst. The catalyst structure and composition were determined by XRD, TEM and EDX, and the results showed that Pt particles deposited on a TiOx support are alloyed with titanium to form an ordered Pt 3 Ti phase. The catalytic activity for ORR was evaluated using the rotating disk electrode (RDE) technique in 0.1M HClO 4 at 25°C, and the results showed that Ti-alloyed Pt/TiOx catalysts exhibited 2-fold higher specific activity than conventional Pt/XC72. This enhanced activity of Pt/TiOx catalysts is believed to be due to the formation of Pt-Ti alloy. Catalyst stability at high potentials was examined by potential cycling between 1.0 and 1.5 V vs RHE in 0.1M HClO 4 at 60°C. While Pt/TiOx catalysts retained their initial electrochemical active area (ECA) after 10000 voltage cycles, Pt/XC72 lost 30–50% of its initial ECA after 10 000 cycles, which indicates that Pt/TiOx catalysts are highly stable under high potential conditions.