Stability of Corrosion-Resistant Magnéli-Phase Ti4O7-Supported PEMFC Catalysts

Abstract

Sub-stoichiometric titanium oxide (Ti4O7)-supported Pt catalysts were prepared and their electrochemical properties, particularly the effects of high potential conditions on the activity and stability of Pt/Ti4O7 catalysts, were examined in comparison to those of Pt/C catalyst. Polarization measurements using MEAs revealed that the Pt/Ti4O7 cathode shows similar activity for the oxygen reduction reaction as Pt/C catalyst at 80oC. A high-potential holding test (1 hour holding at 1.0 - 1.5 V vs. anode) demonstrated that the Pt/Ti4O7 catalyst is quite stable against high potential up to 1.5 V. Similar results were obtained in potential step tests (0.9 V-30 sec./1.3 V-30 sec.). A single cell using a Pt/Ti4O7 cathode was operated at 80oC, and voltage stability for >350 hours with H2/O2 was also demonstrated.