Pt-based bimetallic nanoframes have been demonstrated to have high activity for a number of electrocatalytic reactions. Their morphology, crystal facets, and compositions are important factors that regulate their catalytic activities. Herein, we synthesized a series of Pt-surfaced PtNi dodecahedral nanoframes with variable Pt/Ni ratios. The nanoframes were prepared by oxidative etching of presynthesized PtNi rhombic dodecahedron nanoparticles. The Pt ratio in the PtNi nanoframes have been tuned from 28% to 65% by changing the duration of oxidative etching. In terms of catalytic performance, the PtNi nanoframes display a volcano-type behavior in specific oxygen reduction reaction (ORR) activity as a function of Pt ratio with a maximum ORR specific activity of 1.9 mA cm–2 observed with 47% Pt. The mass activity of the particles ranges from 0.72 to 0.92 A mg–1, which significantly exceeds the mass activity of 0.19 A mg–1 measured for commercial Pt NP/C. Density functional theory calculations reveal that the Pt ratio underneath the Pt skin in the nanoframes affects the binding energy of oxygenate species and thus the ORR activity. The trend of OH binding energy versus PtNi composition from the computational results qualitatively agrees with the trend of ORR activity from the experiments.

The electrochemical oxidation of small organic molecules (SOMs) such as methanol and glucose is a critical process and has relevant applications in fuel cells and sensors. A key challenge in SOM oxidation is the poisoning of the surface by carbon monoxide (CO) and other partially oxidized intermediates, which is attributed to the presence of Pt−Pt pair sites. A promising pathway for overcoming this challenge is to develop catalysts that selectively oxidize SOMs via "direct" pathways that do not form CO as a primary intermediate. In this report, we utilize an ambient, template-based approach to prepare PtAu alloy nanowires with tunable compositions. X-ray photoelectron spectroscopy measurements reveal that the surface composition matches that of the bulk composition after synthesis. Monte Carlo method simulations of the surface structure of PtAu alloys with varying coverage of oxygen adsorbates and varying degrees of oxygen adsorption strength reveal that oxygen adsorption under electrochemical conditions enriches the surface with Pt and a large fraction of Pt−Pt sites remain on the surface even with the Au content of up to 50%. Electrochemical properties and the catalytic performance measurements of the PtAu nanowires for the oxidation of methanol and glucose reveal that the mechanistic pathways that produce CO are suppressed by the addition of relatively small quantities of Au (∼10%), and CO formation can be completely suppressed by 50% Au. The suppression of CO formation with small quantities of Au suggests that the presence of Pt−Au pair sites may be more important in determining the mechanism of SOM oxidation rather than Pt−Pt pair site density.