Synthesis of tailored nanoparticles for palladium-based oxidation catalysts
Doctoral thesis, 2023
The immense changes of physical and chemical properties of materials caused by the transition from microscale to nanoscale have been attracting scientific attention for decades. Rapid development of modern techniques triggers the attention on the multicomponent nanoparticle catalysts with enhanced catalytic activities. In this thesis, the Au@Pd core@shell system and the highly dispersed Pd/CeO2 and Pt/CeO2 are investigated to achieve highly active oxidation catalysts.
The Au@Pd core@shell nanoparticles were synthesized by a two-step seeded growth method. The effects of temperature and Pd/Au molar ratio on the morphology of Au@Pd core@shell nanoparticles were studied. The effect of the Au core on the Pd surface properties was studied by systematically varying the core/shell ratio. Highly dispersed Pd/CeO2 and Pt/CeO2 were prepared by incipient wetness impregnation. High-resolution transmission electron microscopy (HRTEM), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), and energy-dispersive X-ray spectroscopy (EDS) line scanning were utilized to investigate the morphology of the nanoparticle catalysts. Chemical composition was measured by X-ray fluorescence (XRF), and the surface electron structure and chemical state were investigated by X-ray photoelectron spectroscopy (XPS). An environmental reaction cell was used to test the catalytic activity for the CO oxidation reaction. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to study the surface species during CO adsorption and CO oxidation reaction conditions.
It is shown that Au@Pd core@shell nanoparticles with different Au core sizes and Pd shell thickness can be successfully synthesized and loaded onto alumina using precise synthesis conditions. Moreover, neither agglomeration nor destruction of the core@shell motif under CO oxidation reaction conditions could be observed, indicating good structural stability. Further, in situ infrared spectroscopy reveals that palladium surface properties in core@shell system differ to palladium only particles, suggesting electronic and structural modification of the Pd shell surface by the Au core. The Pd shell thickness exceed 0.5 nm as to be active for CO oxidation at low temperatures.
The Au@Pd core@shell nanoparticles were synthesized by a two-step seeded growth method. The effects of temperature and Pd/Au molar ratio on the morphology of Au@Pd core@shell nanoparticles were studied. The effect of the Au core on the Pd surface properties was studied by systematically varying the core/shell ratio. Highly dispersed Pd/CeO2 and Pt/CeO2 were prepared by incipient wetness impregnation. High-resolution transmission electron microscopy (HRTEM), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), and energy-dispersive X-ray spectroscopy (EDS) line scanning were utilized to investigate the morphology of the nanoparticle catalysts. Chemical composition was measured by X-ray fluorescence (XRF), and the surface electron structure and chemical state were investigated by X-ray photoelectron spectroscopy (XPS). An environmental reaction cell was used to test the catalytic activity for the CO oxidation reaction. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to study the surface species during CO adsorption and CO oxidation reaction conditions.
It is shown that Au@Pd core@shell nanoparticles with different Au core sizes and Pd shell thickness can be successfully synthesized and loaded onto alumina using precise synthesis conditions. Moreover, neither agglomeration nor destruction of the core@shell motif under CO oxidation reaction conditions could be observed, indicating good structural stability. Further, in situ infrared spectroscopy reveals that palladium surface properties in core@shell system differ to palladium only particles, suggesting electronic and structural modification of the Pd shell surface by the Au core. The Pd shell thickness exceed 0.5 nm as to be active for CO oxidation at low temperatures.
supported catalysts
CO oxidation
morphology and surface properties
in situ spectroscopy
Pd and Au@Pd nanoparticles
Vasa A, Vasa Hus 2-3 Entrehall
Opponent: Professor Helena Hagelin-Weaver, Department of Chemical Engineering, University of Florida
Author
Yanyue Feng
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Synthesis and Characterization of Catalytically Active Au Core─Pd Shell Nanoparticles Supported on Alumina
Langmuir,;Vol. 38(2022)p. 12859-12870
Journal article
Effect of Au core size and Pd shell thickness on CO oxidation studied by systematic variation of the Au@Pd/Al2O3 model catalyst motif. Yanyue Feng, Anders Hellman, Andreas Schaefer, Mengqiao Di, Felix Hemmingsson, Hanna Härelind, Matthias Bauer, and Per-Anders Carlsson
CO oxidation over highly dispersed palladium ceria catalysts. Yanyue Feng, Andreas Schaefer, Mengqiao Di, Hanna Härelind, and Per-Anders Carlsson
Chasing PtO<inf>x</inf> species in ceria supported platinum during CO oxidation extinction with correlative operando spectroscopic techniques
Journal of Catalysis,;Vol. 409(2022)p. 1-11
Journal article
When the materials change from microscale to nanoscale, their physical and chemical properties will change accordingly. Rapid development of modern techniques triggers the attention on the multicomponent nanoparticle catalysts with enhanced catalytic activities. Among them, the Au core-Pd shell (denoted as Au@Pd) core@shell system and the highly dispersed Pd/CeO2 and Pt/CeO2 have attracted great attention and were investigated in this thesis.
The Au@Pd core@shell system and the highly dispersed Pd/CeO2 and Pt/CeO2 were studied using various techniques like High-resolution transmission electron microscopy (HRTEM), X-ray fluorescence (XRF), and X-ray photoelectron spectroscopy (XPS). In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was also used to study the surface properties.
It is shown that Au@Pd core@shell nanoparticles with different Au core sizes and Pd shell thickness can be successfully synthesized and loaded onto alumina using precise synthesis conditions. Moreover, neither agglomeration nor destruction of the core@shell motif under CO oxidation reaction conditions could be observed, indicating good structural stability. Further, in situ infrared spectroscopy reveals that palladium surface properties in the core@shell system differ to palladium only particles, suggesting electronic and structural modification of the Pd shell surface by the Au core. The catalyst is active towards CO oxidation at low temperature when the Pd shell thickness exceeds 0.5 nm.
The Au@Pd core@shell system and the highly dispersed Pd/CeO2 and Pt/CeO2 were studied using various techniques like High-resolution transmission electron microscopy (HRTEM), X-ray fluorescence (XRF), and X-ray photoelectron spectroscopy (XPS). In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was also used to study the surface properties.
It is shown that Au@Pd core@shell nanoparticles with different Au core sizes and Pd shell thickness can be successfully synthesized and loaded onto alumina using precise synthesis conditions. Moreover, neither agglomeration nor destruction of the core@shell motif under CO oxidation reaction conditions could be observed, indicating good structural stability. Further, in situ infrared spectroscopy reveals that palladium surface properties in the core@shell system differ to palladium only particles, suggesting electronic and structural modification of the Pd shell surface by the Au core. The catalyst is active towards CO oxidation at low temperature when the Pd shell thickness exceeds 0.5 nm.
Synergistic development of X-ray techniques and applicable thin oxides for sustainable chemistry
Swedish Research Council (VR) (2017-06709), 2018-04-04 -- 2021-12-31.
Subject Categories
Materials Chemistry
Infrastructure
Chalmers Materials Analysis Laboratory
Areas of Advance
Materials Science
ISBN
978-91-7905-800-5
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5266
Publisher
Chalmers
Vasa A, Vasa Hus 2-3 Entrehall
Opponent: Professor Helena Hagelin-Weaver, Department of Chemical Engineering, University of Florida