Abstract
Supported bimetallic nanoparticles (BNPs) are promising catalysts, but study on their compositional and structural changes under reaction conditions remains a challenge. In this work, the structure of PtNi BNPs supported on UiO-67 metal–organic framework (MOF) catalyst (i.e., PtNi@UiO-67) was investigated by in situ by near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS). The results showed differences in the reduction behaviour of Ni species in PtNi BNPs and monometallic Ni supported on UiO-67 catalysts (i.e., PtNi@UiO-67 and Ni@UiO-67), suggesting charge transfer between metallic Pt and Ni oxides in PtNi@UiO-67. Under CO oxidation conditions, Ni oxides segregated to the outer surface of the BNPs forming a thin layer of NiOx on top of the metallic Pt (i.e., a NiOx-on-Pt structure). This resulted in a core-shell structure which was confirmed by high-resolution scanning transmission electron microscopy (HR-STEM). Accordingly, the layer of NiOx on PtNi BNPs, which is stabilised by charge transfer from metallic Pt, was proposed as the possible active phase for CO oxidation, being responsible for the enhanced catalytic activity observed in the bimetallic PtNi@UiO-67 catalyst.
Original language | English |
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Pages (from-to) | 522-529 |
Number of pages | 8 |
Journal | Journal of Catalysis |
Volume | 391 |
Early online date | 24 Sept 2020 |
DOIs | |
Publication status | Published - 30 Nov 2020 |
Funding
R.V. acknowledges The University of Manchester President’s Doctoral Scholar Award for supporting his PhD research in the United Kingdom. We thank Diamond Light Source for access and support in use of the electron Physical Science Imaging Centre (Instrument E01, proposal number MG23221 ) that contributed to the results presented here. NAP-XPS measurements in this work were performed at the Henry Royce Institute for Advanced Materials, funded through EPSRC grants EP/R00661X/1 and EP/P025021/1 .
Keywords
- Bimetallic nanoparticle catalysts (BNPs)
- CO oxidation
- High-resolution scanning transmission electron microscopy (HRS-TEM)
- Metal-organic frameworks (MOFs)
- Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS)
ASJC Scopus subject areas
- Catalysis
- Physical and Theoretical Chemistry
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Headspace gas mass spectrometer (headspace gas MS)
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