Ta Modified TiO 2 Supports Exhibit Exceptional Durability in Polymer Electrolyte Fuel Cells Amod Kumar and Vijay Ramani Center for Electrochemical Science and Engineering Department of Chemical and Biological Engineering Illinois Institute of Technology, Chicago, IL 60616, USA Ta modified TiO 2 was synthesized using a sol-gel procedure and evaluated for use as an electrocatalyst support. Of the materials evaluated, Ta 0.3 Ti 0.7 O 2 exhibited remarkably high stability under aggressive potential cycling tests designed to mimic harsh automotive drive cycles. The capacitance of the Ta 0.3 Ti 0.7 O 2 support changed by 12% whereas the pseudocapacitance of a carbon benchmark changed by over 100% under identical test conditions. Pt/Ta 0.3 Ti 0.7 O 2 electrocatalyst prepared by catalyzing this support showed high electrochemical stability which was attributed to a strong metal support interaction (SMSI); and fairly good performance. The stability of the catalyzed supports were evaluated by monitoring the evolution of the electrochemical surface area (ECSA) under potential cycling, loss in ECSA of Pt/Ta 0.3 Ti 0.7 O 2 was found to be 35% compared to 46% for Pt/C over 10,000 load cycles. Pt/Ta 0.3 Ti 0.7 O 2 showed fairly good performance: the electrochemical surface area of this electrocatalyst was 41 m 2 /g, while the mass activity and area- specific activities for the oxygen reduction reaction (ORR) were 62 mA/mg Pt and 151 μA/cm 2 Pt , respectively, as ascertained from electrochemical experiments performed on a rotating disk electrode (RDE). Based on these results, we propose that Ta 0.3 Ti 0.7 O 2 is an excellent corrosion-resistant alternative to carbon as an electrocatalyst support. Introduction Polymer electrolyte fuel cells (PEFCs) have shown tremendous promise for automotive, stationary, and portable applications. There are, however, several challenges that need to be addressed before successful commercialization of PEFC technology is realized. Currently, platinum supported on carbon (Pt/C) is recognized as the state-of-the-art catalyst in PEFCs.(1) Carbon possesses many desirable properties for a suitable catalyst support such as high electron conductivity and high surface area, which allows high dispersion of catalyst metal.(2) Therefore, it is widely used as a catalyst support material in PEFCs. However, carbon suffers from electrochemical degradation under conditions of high temperature, high humidity, high electrode potential, and low pH.(3, 4) Carbon corrosion occurs by the following reaction:(5) C + 2H 2 O -> CO 2 + 4H + + 4e - 0.207 V vs. RHE [1] 10.1149/05801.1823ecst ©The Electrochemical Society ECS Transactions, 58 (1) 1823-1834 (2013) 1823