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

Abstract

Nano-sized sub-stoichiometric titanium oxide (TiOx), synthesized by pulsed UV laser irradiation of TiO2, 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 Pt3Ti phase. The catalytic activity for ORR was evaluated using the rotating disk electrode (RDE) technique in 0.1M HClO4 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 HClO4 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.