Development of carbon supported Pt based alloy catalysts with Pt skin layer for oxygen reduction reaction
Proton exchange membrane fuel cells (PEMFCs) are receiving much attention because of their high energy efficiency and the fact that they do not emit carbon dioxide. However, the use of expensive platinum as a catalyst to overcome the slow oxygen reduction reaction (ORR) at low temperature is recognized as one of the obstacles to commercialization. To solve this problem, many studies have been conducted to reduce the amount of platinum used and simultaneously increase the catalytic activity. A modified protective coating method has been developed to produce Pt-Ni alloys with a Pt-rich shell using a carbon protective layer and ozone treatment. The carbon protective layer prepared by carbonization of polydopamine suppresses the aggregation of particles during high temperature heat treatment. Later, this carbon layer should be removed because it blocks the reaction site where the oxygen reduction reaction takes place. Ozone is a highly oxidative gas and can selectively remove the amorphous carbon layer without affecting the catalytic properties. In addition, ozone is environmentally friendly with a short half-life, and it is suitable for mass production because it takes 7 minutes at room temperature. The Pt2Ni1/C-ozone catalyst prepared by this method exhibited excellent ORR activity and performance in PEMFC compared to commercial Pt/C catalysts.