Abstract
Platinum-based alloys are known to demonstrate advanced properties in electrochemical reactions that are relevant for proton exchange membrane fuel cells and electrolyzers. Further development of Pt alloy electrocatalysts relies on the design of architectures with highly active surfaces and optimized utilization of the expensive element, Pt. Here, we show that the three-dimensional Pt anisotropy of Pt-Ni rhombic dodecahedra can be tuned by controlling the ratio between Pt and Ni precursors such that either a completely hollow nanoframe or a new architecture, the excavated nanoframe, can be obtained. The excavated nanoframe showed ∼10 times higher specific and ∼6 times higher mass activity for the oxygen reduction reaction than Pt/C, and twice the mass activity of the hollow nanoframe. The high activity is attributed to enhanced Ni content in the near-surface region and the extended two-dimensional sheet structure within the nanoframe that minimizes the number of buried Pt sites.
| Original language | English |
|---|---|
| Pages (from-to) | 11678-11681 |
| Number of pages | 4 |
| Journal | Journal of the American Chemical Society |
| Volume | 139 |
| Issue number | 34 |
| DOIs | |
| State | Published - Aug 30 2017 |
Funding
The research conducted at Lawrence Berkeley National Laboratory, which is a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-05CH11231, was supported by U.S. Department of Energy, the Office of Energy Efficiency and Renewable Energy, Fuel Cell Technologies. HRTEM, STEM-HAADF, EDS mapping, SEM, and XPS were collected at the Molecular Foundry. We acknowledge M. Marcus, S. Fakra, C. Xie, Q. Kong, H. Zhang, and the use of Beamline 10.3.2 at the Advanced Light Source for help with collection of EXAFS data. Work at the Molecular Foundry and the Advanced Light Source was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. D.K. acknowledges support from Samsung Scholarship. T.L. acknowledges fellowship support from Suzhou Industrial Park. We acknowledge E. Kreimer of the Microanalytical Facility in the College of Chemistry, UC Berkeley for access to ICP. The research performed at Argonne National Laboratory, which is a U.S. Department of Energy Office of Science Laboratory operated by UChicago Argonne, LLC under Contract No. DE-AC02-06CH11357, was supported by U.S. Department of Energy, the Office of Energy Efficiency and Renewable Energy, Fuel Cell Technologies. STEM-based electron tomography experiments were performed as part of a user project at ORNL’s Center for Nanophase Materials Sciences (CNMS), which is a U.S. Department of Energy Office of Science User Facility.