Oxygen Reduction Activity of Dealloyed Pt1-xNix Catalysts

Pt and intermixed Pt1-xNix (0.65 < x < 0.75) catalysts were sputtered-deposited onto both bare and nanostructured thin film (NSTF)-coated glassy carbon disks. The oxygen reduction reaction (ORR) activities of the disks were determined from Rotating Disk Electrode (RDE) measurements. Experiments on the NTSF-coated disks examined both catalytic activities and the effects of high surface area supports in a single measurement. The RDE measurement protocols were designed to examine changes in catalyst properties and performance during de-alloying and thus did not include the typical "electrochemical cleaning" procedure at the beginning. Instead, a continuous CV-ORR measurement protocol was used to monitor the electrochemical performance indicators such as active surface area (SEF) and ORR kinetic current density of the catalysts over the course of 9 h. As an example, the SEF of Pt25Ni75 on the NSTF-support was initially 20 cm(Pt)(2)/cm(planar)(2) and the SEF increased rapidly at the beginning of the experiment, then stabilized near similar to 50 cm(2)/cm(2) as Ni de-alloyed. This is compared with sputtered Pt on NSTF support that showed SEF similar to 15 cm(2)/cm(2). De-alloying is an effective way to create Pt-transition metal catalysts on NSTF with extremely high active surface area. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3595749] All rights reserved.