Octahedral Pd@Pt_1.8Ni Core–Shell Nanocrystals with Ultrathin PtNi Alloy Shells as Active Catalysts for Oxygen Reduction Reaction

Abstract

Forming core-shell and alloy structures offers generally two ways to design efficient Pt-based catalysts for oxygen reduction reaction (ORR). Here, we combined these two strategies and invented a versatile aqueous route to synthesize octahedral Pd@Pt1.8Ni core-shell nanocrystals. The Pt/Ni atomic ratios in the resultant shells can be varied from 0.6 to 1.8, simply by changing the amounts of Pt and Ni precursors, with the other conditions unchanged. Experimental studies showed that the mass activities of as-prepared catalysts were 5 times higher than that of the commercial Pt/C. We believe that the ultrathin PtNi shells enclosed by {111} facets made it possible to reduce the Pt content while retaining the catalytic activity toward ORR. This strategy may be extended to the preparation of other multimetallic nanocrystals with shaped and ultrathin alloy shells, which is conducive to design highly active catalysts.

Oxygen Reduction Activity and Durability of Ordered and Disordered Pt3Co Alloy Nanoparticle Catalysts at Practical Temperatures of Polymer Electrolyte Fuel Cells

“…• C, the amount of Co remaining in the ordered-Pt 3 Co rapidly decreased, within several hours, and reached a steady value of 75% (average composition of Pt 81 Co 19 ) after 20 h. In contrast, the Co dissolution rate from the disordered-Pt 3 Co was slower than that for the ordered-Pt 3 Co, resulting in a slightly larger remaining percentage (80%). At 80…”

“…2∼7 times compared to that of pure Pt. The enhancement factor has been found to depend on various properties of alloy nanoparticles, e.g., composition, 4,[14][15][16] shape (or size), [17][18][19][20][21] and crystal structure. [22][23][24][25][26][27][28][29] For example, the values of j k for Pt-Co alloys showed a maximum at the atomic ratio of Pt/Co = 3.…”

2D ultrathin core–shell Pd@Ptmonolayer nanosheets: defect-mediated thin film growth and enhanced oxygen reduction performance

“…For example, extended (110) and (111) Pt crystal planes were found to be far more active than (100) plane and those less ordered surfaces as often found in most nanostructures, especially in perchloric acid 11 . Alloying the surface or near surface region of Pt catalysts with other elements is another effective strategy to enhance the intrinsic surface activity of Pt-based ORR catalysts 10,[12][13][14] . Therefore, it is highly challenging to design a high surface area Pt electrocatalyst that shows both intrinsic activity and long term durability.…”

Highly Active and Stable Pt–Pd Alloy Catalysts Synthesized by Room‐Temperature Electron Reduction for Oxygen Reduction Reaction

“…Since the lattice constants and chemical reactivity of Pt and Pd are very similar, they can be readily prepared as alloy or core–shell nanocrystals through chemical or electrical methods 13. In addition, Pd is a good candidate to help reduce the high cost of the Pt/C catalyst because the current price of Pd is only half of that of Pt.…”