Truncated Octahedral Pt₃Ni Oxygen Reduction Reaction Electrocatalysts

Abstract

This communication describes the preparation of carbon-supported truncated-octahedral Pt(3)Ni nanoparticle catalysts for the oxygen reduction reaction. Besides the composition, size, and shape controls, this work develops a new butylamine-based surface treatment approach for removing the long-alkane-chain capping agents used in the solution-phase synthesis. These Pt(3)Ni catalysts can have an area-specific activity as high as 850 muA/cm(2)(Pt) at 0.9 V, which is approximately 4 times better than the commercial Pt/C catalyst ( approximately 0.2 mA/cm(2)(Pt) at 0.9 V). The mass activity reached 0.53 A/mg(Pt) at 0.9 V, which is close to a factor of 4 increase in mass activity, the threshold value that allows fuel-cell power trains to become cost-competitive with their internal-combustion counterparts. Our results also show that the mass activities of these carbon-supported Pt(3)Ni nanoparticle catalysts strongly depend on the (111) surface fraction, which validates the results of studies based on Pt(3)Ni extended-single-crystal surfaces, suggesting that further development of catalysts with still higher mass activities is highly plausible.

Editors' Choice—Electrochemically Active Surface Area Measurement of Aged Pt Alloy Catalysts in PEM Fuel Cells by CO Stripping

“…In contrast, PtCo/C-80 with a thicker Pt skin was able to sustain its high activity despite a slightly lower initial activity. Octahedral PtNi nanoparticles which expose a predominance of extremely high activity PtNi(111) show impressive activity in RDE, 19,[28][29][30][31][32][33] yet when measured in an MEA, only a small fraction of the activity was realized. 1 The very thin Pt skin and a high transition metal dissolution rate are believed to be the predominant causes of its instability.…”

Carbon-Supported Pt-Based Alloy Electrocatalysts for the Oxygen Reduction Reaction in Polymer Electrolyte Membrane Fuel Cells: Particle Size, Shape, and Composition Manipulation and Their Impact to Activity

“…288 The population of the truncated-octahedral shape depended on the types and amounts of reducing and capping agents used. Wu et al 288 believed that the two types of long-alkane-chain amines resulted in different portions of truncated octahedral: when hexadecylamine was used as a capping agent, a small portion of cubes was observed (Figure 15a,b) while the use of dodecylamine led to 100% truncated-octahedral nanocrystals of Pt 3 Ni, as shown in Figure 14c. In addition to the use of different alkane chain lengths, a combination of strong (boranetert-butylamine complex, TBAB) and mild (hexadecanediol) reducing agents was used to effectively adjust the nucleation and growth rate.…”

“…248,341 Wu et al 288 reported truncated-octahedral Pt 3 Ni (t,o-Pt 3 Ni) catalysts with a particle size of 5−7 nm that had a dominant exposure of {111} facets. Three sets of Pt 3 Ni nanocrystals were generated with various mixtures of truncated octahedral (exposing both {111} and {100} facets) and cubes (exposing only {100} facets).…”

Exploring the phase space of time of flight mass selected PtxY nanoparticles

“…Improvements can be made to catalysts by forming non-equilibrium morphologies. 14,38,[49][50][51][52][53] Very recent results by Chen et al 13 have shown unprecedented capabilities of Pt x Ni ''nanoframes'' to catalyze oxygen reduction.…”