Oleylamine Aging of PtNi Nanoparticles Giving Enhanced Functionality for the Oxygen Reduction Reaction

Gerard M Leteba; Yi-Chi Wang; Thomas J A Slater; Rongsheng Cai; Conor Byrne; Christopher P Race; David R G Mitchell; Pieter B J Levecque; Neil P Young; Stuart M Holmes; Alex Walton; Angus I Kirkland; Sarah J Haigh; Candace I Lang

doi:10.1021/acs.nanolett.1c00706

Oleylamine Aging of PtNi Nanoparticles Giving Enhanced Functionality for the Oxygen Reduction Reaction

Nano Lett. 2021 May 12;21(9):3989-3996. doi: 10.1021/acs.nanolett.1c00706. Epub 2021 Apr 26.

Authors

Gerard M Leteba^{1

2}, Yi-Chi Wang^{3

4

5}, Thomas J A Slater^{3

6}, Rongsheng Cai³, Conor Byrne^{7

8}, Christopher P Race³, David R G Mitchell⁹, Pieter B J Levecque¹, Neil P Young¹⁰, Stuart M Holmes¹¹, Alex Walton^{7

8}, Angus I Kirkland^{6

10}, Sarah J Haigh³, Candace I Lang²

Affiliations

¹ Catalysis Institute, Department of Chemical Engineering, University of Cape Town, Corner of Madiba Circle and South Lane, Rondebosch 7701, South Africa.
² School of Engineering, Macquarie University, Sydney, New South Wales 2109 Australia.
³ Department of Materials, University of Manchester, Manchester M13 9PL, United Kingdom.
⁴ Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, China.
⁵ School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100049, China.
⁶ Electron Physical Sciences Imaging Centre, Diamond Light Source Ltd., Oxfordshire OX11 0DE, United Kingdom.
⁷ Department of Chemistry, University of Manchester, Manchester M13 9PL, United Kingdom.
⁸ Photon Science Institute, University of Manchester, Manchester M13 9PL, United Kingdom.
⁹ Electron Microscopy Centre, Innovation Campus, University of Wollongong, Wollongong, New South Wales 2517, Australia.
¹⁰ Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom.
¹¹ Department of Chemical Engineering and Analytical Science, University of Manchester, Manchester M13 9PL, United Kingdom.

Abstract

We report a rapid solution-phase strategy to synthesize alloyed PtNi nanoparticles which demonstrate outstanding functionality for the oxygen reduction reaction (ORR). This one-pot coreduction colloidal synthesis results in a monodisperse population of single-crystal nanoparticles of rhombic dodecahedral morphology with Pt-enriched edges and compositions close to Pt₁Ni₂. We use nanoscale 3D compositional analysis to reveal for the first time that oleylamine (OAm)-aging of the rhombic dodecahedral Pt₁Ni₂ particles results in Ni leaching from surface facets, producing aged particles with concave faceting, an exceptionally high surface area, and a composition of Pt₂Ni₁. We show that the modified atomic nanostructures catalytically outperform the original PtNi rhombic dodecahedral particles by more than two-fold and also yield improved cycling durability. Their functionality for the ORR far exceeds commercially available Pt/C nanoparticle electrocatalysts, both in terms of mass-specific activities (up to a 25-fold increase) and intrinsic area-specific activities (up to a 27-fold increase).

Keywords: ORR; PEMFC; STEM-EDS; electrocatalyst; electron tomography; nanoparticle.