Oxygen Reduction Activity of Dealloyed Pt1–xNix Catalysts

Pt and intermixed Pt 1–x Ni x (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 Pt 25 Ni 75 on the NSTF-support was initially 20 cm 2 Pt /cm 2 planar and the SEF increased rapidly at the beginning of the experiment, then stabilized near ∼50 cm 2 /cm 2 as Ni de-alloyed. This is compared with sputtered Pt on NSTF support that showed SEF ∼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.