Platinum (Pt) is a critical component in catalyzing the oxygen reduction reaction (ORR) in polymer membrane fuel cells. Yet the low abundance and high cost of Pt have hindered the commercialization of this clean-energy technology. It is therefore critical to design new types of Pt catalysts that both enhance catalytic activity and durability while reducing the amount of Pt needed. Here we report using a solution-based atomic layer-by-layer deposition process to controllably deposit layers of Pt onto Pd decahedral seed particles. However, as opposed to the conformal Pt shells observed in cubic, octahedral, and icosahedral Pd seed systems, Pt atoms deposited onto Pd decahedra instead form a non-uniform, concave structure with high-index facets, with Pt atoms preferentially remaining at the high energy sites along the vertices and edges of the decahedra even at high reaction temperatures. Compared to commercial Pt/C catalyst, the Pd@Pt concave decahedra demonstrate substantial enhancement in both the catalytic activity and durability toward the ORR. The specific and mass activities of concave decahedra with 29.6% Pt by weight showed specific and mass activities for ORR enhanced by 4.4 and 6.6 times relative to commercial Pt/C, respectively. Furthermore, after an accelerated durability test of 10,000 cycles, the Pd@Pt decahedra still demonstrated a mass activity over twice that of the pristine Pt/C.

Pd@Pt core-shell concave decahedra: A class of catalysts for enhancing the oxygen reduction reaction

251st National Meeting (2016)

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