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Characterization of Supported Catalytic Metallic Nanoparticles using Transmission Electron Microscopy

Persson, Axel LU (2015) KOO920 20151
Centre for Analysis and Synthesis
Abstract
In this project catalysts have been analyzed, in the sense of size and composition, using a Transmission Electron Microscope (TEM). This important class of substances are used to facilitate chemical reactions, in everything from specific molecular research to conversion car emissions which explains the importance of research. Nanoparticles of gold (Au) have been shown to have good catalytic performance. However, optimization in size is crucial due to the different facets present at different sizes. TEM has been used to image the catalysts, using contrast in different modes of operation to distinguish the gold from the carrier oxide which is there to prevent agglomeration of the gold. Sizes of the Au nanoparticles ranged from 5 to 16 nm... (More)
In this project catalysts have been analyzed, in the sense of size and composition, using a Transmission Electron Microscope (TEM). This important class of substances are used to facilitate chemical reactions, in everything from specific molecular research to conversion car emissions which explains the importance of research. Nanoparticles of gold (Au) have been shown to have good catalytic performance. However, optimization in size is crucial due to the different facets present at different sizes. TEM has been used to image the catalysts, using contrast in different modes of operation to distinguish the gold from the carrier oxide which is there to prevent agglomeration of the gold. Sizes of the Au nanoparticles ranged from 5 to 16 nm without any agglomeration observed. Further, so called Molecular Imprinted Polymers, MIPs, were analyzed for their elemental content and to make sure no palladium (Pd) from the palladium containing molecules had reduced to metallic particles during polymerization. The results were promising in the sense that stable low levels of Pd without any metallic palladium were observed. TEM-modes used were different in how well they could distinguish the particles. Conventional imaging (CTEM) proved difficult since high scattering occurred from thicker oxide as well. While scanning TEM (STEM) was the preferred method due to the clearer results in its HAADF-mode (High Angle Annular Dark Field). Together with X-ray Energy Dispersive Spectroscopy (XEDS) STEM provided compelling images and elemental maps of where gold was found in the clusters. One could also pick certain points in the image to get local composition, useful for the MIP-analysis. (Less)
Popular Abstract (Swedish)
Katalysatorer är viktiga för effektivisering av både industri och spetsforskning. Att se enstaka atomer är inte möjligt i vanliga ljusmikroskop, så högupplösande elektronmikroskop har använts för att bestämma storlek hos katalytiska guldnanopartiklar mellan 5 och 20nm.
Please use this url to cite or link to this publication:
author
Persson, Axel LU
supervisor
organization
alternative title
Karakterisering av Uppburna Katalytiska Metallnanopartiklar med hjälp av Transmissionselektronmikroskop
course
KOO920 20151
year
type
H2 - Master's Degree (Two Years)
subject
keywords
materials chemistry, materialkemi, metallic nanoparticles, transmission electron microscopy
language
English
id
7360199
date added to LUP
2016-08-01 11:06:24
date last changed
2016-08-01 11:08:39
@misc{7360199,
  abstract     = {In this project catalysts have been analyzed, in the sense of size and composition, using a Transmission Electron Microscope (TEM). This important class of substances are used to facilitate chemical reactions, in everything from specific molecular research to conversion car emissions which explains the importance of research. Nanoparticles of gold (Au) have been shown to have good catalytic performance. However, optimization in size is crucial due to the different facets present at different sizes. TEM has been used to image the catalysts, using contrast in different modes of operation to distinguish the gold from the carrier oxide which is there to prevent agglomeration of the gold. Sizes of the Au nanoparticles ranged from 5 to 16 nm without any agglomeration observed. Further, so called Molecular Imprinted Polymers, MIPs, were analyzed for their elemental content and to make sure no palladium (Pd) from the palladium containing molecules had reduced to metallic particles during polymerization. The results were promising in the sense that stable low levels of Pd without any metallic palladium were observed. TEM-modes used were different in how well they could distinguish the particles. Conventional imaging (CTEM) proved difficult since high scattering occurred from thicker oxide as well. While scanning TEM (STEM) was the preferred method due to the clearer results in its HAADF-mode (High Angle Annular Dark Field). Together with X-ray Energy Dispersive Spectroscopy (XEDS) STEM provided compelling images and elemental maps of where gold was found in the clusters. One could also pick certain points in the image to get local composition, useful for the MIP-analysis.},
  author       = {Persson, Axel},
  keyword      = {materials chemistry,materialkemi,metallic nanoparticles,transmission electron microscopy},
  language     = {eng},
  note         = {Student Paper},
  title        = {Characterization of Supported Catalytic Metallic Nanoparticles using Transmission Electron Microscopy},
  year         = {2015},
}