Tuning the Electrocatalytic Oxygen Reduction Reaction Activity of PtCo Nanocrystals by Cobalt Concentration with Atomic-Scale Understanding
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, United States; Departments of Chemistry and Materials Science & Engineering University of Pennsylvania
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, United States
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104, United States
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, United States
- Departments of Chemistry and Materials Science & Engineering, University of Pennsylvania, Philadelphia, PA 19104, United States
The development of a suitable catalyst for the oxygen reduction reaction (ORR) – the cathode reaction of proton exchange membrane fuel cells (PEMFC) – is necessary to push this technology towards widespread adoption. There have been substantial efforts to utilize bimetallic Pt-M alloys that adopt the ordered face-centered tetragonal (L10) phase in order to reduce the usage of precious metal, enhance the ORR performance, and improve catalyst stability. In this work, monodisperse Pt-Co nanocrystals (NCs) with well-defined size (4-5 nm) and cobalt composition (25-75 at%) were synthesized via colloidal synthesis. The transformation from the chemically disordered A1 (face-centered cubic, fcc) to the L10 phase was achieved via thermal annealing using both a conventional oven and a rapid thermal annealing process. The structure of the Pt-Co catalysts was characterized by a variety of techniques, including transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy in high-angle annular dark-field scanning transmission electron microscopy (STEM-EDS), small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), and inductively coupled plasma-optical emission spectrometry (ICP-OES). The effects of annealing temperature on the composition-dependent degree of ordering, and subsequent effect on ORR activity is described. This work provides insights regarding the optimal spatial distribution of elements at the atomic level to achieve enhanced ORR activity and stability.
- Research Organization:
- Univ. of Pennsylvania, Philadelphia, PA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Transportation Office. Fuel Cell Technologies Office
- Contributing Organization:
- This research used resources of the Center for Functional Nanomaterials; Brookhaven National Laboratory (BNL); and was supported by the U.S. Department of Energy; Office of Science; Office of Workforce Development for Teachers and Scientists; Office of Science Graduate Student Research (SCGSR) program. J.D.L acknowledge the support from the SCGSR program; which is administered by the Oak Ridge Institute for Science and Education (ORISE) for the DOE. ORISE is managed by ORAU under contract number DE-SC0014664. Magnetic property measurements were supported by NSF MRSEC DMR-1720530. J.D.L acknowledges Dr. Kotaro Sasaki at the Brookhaven National Laboratory for the assistance with the RDE measurements at the Chemistry Division. C.B.M. acknowledges the Richard Perry University Professorship at the University of Pennsylvania.
- Grant/Contract Number:
- SC0014664; AC52-06NA25396
- OSTI ID:
- 1532515
- Journal Information:
- ACS Applied Materials and Interfaces, Journal Name: ACS Applied Materials and Interfaces Journal Issue: 30 Vol. 11; ISSN 1944-8244
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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