High Stability, High Activity Pt/ITO Oxygen Reduction Electrocatalysts

Sn-doped indium oxide (ITO) nanoparticles (NPs) were conceived as a high stability noncarbon support for Pt NPs, and the activity and stability of Pt/ITO for the oxygen reduction reaction (ORR) were probed. Sn was employed as the In2O3 dopant to exploit the strong interaction between Sn and Pt that was previously reported to enhance the activity of Pt on Pt/SnO2, while concomitantly avoiding the intrinsic stability limitations of SnO2 and leveraging the high stability of bulk In2O3 at ORR relevant potentials. The mass activity of Pt was extremely high on Pt/ITO, 621 ± 31 mA/mgPt, which far exceeded the 2015 DOE goal for Pt mass activity of 440 mA/mgPt. The enhanced ORR activity was linked to the faceting of the Pt NPs, which overwhelmingly consisted of Pt (111) facets. The stability of Pt/ITO was also very impressive, with the electrochemically active area unchanged and the Pt half wave potential shifting only 4 mV over 1000 potential cycles to 1.4 V vs RHE, a very harsh condition for ORR electrocatalysts where state-of-the-art Pt/C electrocatalysts typically show very poor stability.