Pt–Au–Co Alloy Electrocatalysts Demonstrating Enhanced Activity and Durability toward the Oxygen Reduction Reaction

Abstract

Here we investigate the oxygen reduction reaction electrocatalytic activity and the corrosion stability of several ternary Pt−Au−Co and Pt−Ir−Co alloys, with Pt−Au−Co having never been previously studied for ORR. The addition of Au fine tunes the lattice parameter and the surface electronic structure to enable activity and cycling stability that is unachievable in Pt−25 atom % Co (state-of-the-art binary baseline). The ternary alloys exhibit a volcano-type dependence of catalytic efficacy on the content of Au or Ir. Pt−2.5 atom % Au−25 atom % Co alloy shows a specific activity of 1.41 mA cm −2 at 0.95 V, which is 16% and 404% higher than those of identically synthesized Pt−Co and pure Pt, respectively. This enhancement is promising in comparison to a range of previously published Pt "skeleton" and Pt "skin" alloys and is in fact the most optimum reported for a skeleton-type system. The catalysts exhibit dramatically improved corrosion stability with increasing levels of Au or Ir substitution, with the specific activity of all the ternary alloys being superior to that of Pt−Co after 100,000 potential cycles of 0.6−1.0 V. For instance, postcycled Pt−10 atom % Au−25 atom % Co shows a specific activity of 0.63 mA cm −2 , which is 140% higher than that of Pt−Co and 439% higher than that of Pt. HRTEM and XPS shows that Au alloying promotes the formation of an atomically thin Pt−Au-rich surface layer, which imparts kinetic stabilization against the dissolution of the less noble solute component.

Perspective of Surfactant‐Free Colloidal Nanoparticles in Heterogeneous Catalysis

“…Here, the selective corrosion (leaching) of less noble metals is often used for synthesis, with less noble metal being dissolved from the surface leaving a nanoporous structure that is composed of the more noble and active metal (see PtCu, PtNi, CuAu, or AgAu). Moreover, outstanding activities were additionally found in case of ternary alloys e. g. PtIrCo, PtAuCo, PtCuCo, PtNiCu, PtNi 3 M (M−Cu, Co, Cr), only to name a few.…”

Elemental Anisotropic Growth and Atomic-Scale Structure of Shape-Controlled Octahedral Pt–Ni–Co Alloy Nanocatalysts

“…Furthermore, the entropic negative contribution to the Gibbs free energy of mixing for the ternary system respect to the two binaries will favorably contribute to stability. So a number of reports have dealt with Pt-based ternary alloy nanoparticles for ORR [29][30][31], , but none has put effort in tailoring their morphological shape [32][33][34] . Now, on the basis of previous studies, Pt-Co binary alloy catalysts also exhibit high activity and stability [35][36][37][38] and for that reason, spherical PtNiCo ternary alloys have attracted more attention as a family of ORR catalysts that would allow tuning both ORR activity and stability [39][40][41][42] .…”

One-step synthesis of the PdPt bimetallic nanodendrites with controllable composition for methanol oxidation reaction

“…Moreover, according to XPS data for the Pd 52 Pt 48 catalyst, the negative shift for the binding energy of Pt occurred. As is well known, the shift in binding energies is associated with the variation in the d-band center [41]. The ARTICLES .…”

“…Specifically, Pt would draw electrons from Pd due to the larger electronegativity of Pt (2.28) compared with that of Pd (2.20) [40]. The change would then cause partial filling of the Pt 5d bands, resulting in a downshift of the d-band center [41].…”