Facile Preparation of a Surface-Enriched Pt Layer Over Pd/C as an Efficient Oxygen Reduction Catalyst With Enhanced Activity and Stability

Abstract

Pt-enriched surface layer formation on Vulcan carbon-supported Pd (Pt@Pd/C) was successfully prepared through a simple and one-pot formic acid reduction approach without any stabilizing agent. The electrocatalytic performance of Pt@Pd/C catalyst toward an oxygen reduction reaction (ORR) in alkaline medium was studied and also compared with standard carbon-supported Pt (Pt/C) and Pd (Pd/C) catalysts. The Pt@Pd/C exhibits higher electrochemical active surface area (74.7 m2/g) and mass activity (1.38 mA/µg) than Pt/C, Pd/C, and contending with standard reported catalysts. In durability tests, Pt@Pd/C showed negligible loss of intrinsic activity (∼10%) after 10,000 cycles which confirmed improved stability than Pt-based catalysts for ORR in KOH medium. This improved electrocatalytic performance could be attributed to their structural characteristics of the Pt-enriched surface layer on Pd/C-core and the compressive lattice strain on Pt. The present investigation demonstrates the simple preparation procedure for surface-enriched Pt on Pd/C and its improved performance for ORR, suggesting that it is a promising contender to benchmark ORR catalysts for alkaline fuel cells.