Abstract

Ta modified TiO2 was synthesized using a sol-gel procedure and evaluated for use as an electrocatalyst support. Of the materials evaluated, Ta0.3Ti0.7O2 exhibited remarkably high stability under aggressive potential cycling tests designed to mimic harsh automotive drive cycles. The capacitance of the Ta0.3Ti0.7O2 support changed by 12% whereas the pseudocapacitance of a carbon benchmark changed by over 100% under identical test conditions. Pt/Ta0.3Ti0.7O2 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/Ta0.3Ti0.7O2 was found to be 35% compared to 46% for Pt/C over 10,000 load cycles. Pt/Ta0.3Ti0.7O2 showed fairly good performance: the electrochemical surface area of this electrocatalyst was 41 m2/g, while the mass activity and area-specific activities for the oxygen reduction reaction (ORR) were 62 mA/mgPt and 151 µA/cm2 Pt, respectively, as ascertained from electrochemical experiments performed on a rotating disk electrode (RDE). Based on these results, we propose that Ta0.3Ti0.7O2 is an excellent corrosion-resistant alternative to carbon as an electrocatalyst support.

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