magistrsko delo
Ana Rebeka Kamšek (Author), Simon Čopar (Mentor), Goran Dražić (Co-mentor)

Abstract

Vrstična presevna elektronska mikroskopija na identični lokaciji je metoda za karakterizacijo materialov, ki omogoča slikanje istih območij materiala pred in po nekem postopku. Uporaba te metode za opazovanje spreminjanja katalizatorjev za uporabo v vodikovih gorivnih celicah, ki so v obliki kovinskih nanodelcev na ogljikovi podlagi, omogoča zanesljivo ocenjevanje odnosov med njihovo strukturo in stabilnostjo, saj spremembe materiala lahko opazujemo na atomski skali. Za hitrejšo, bolj objektivno in ponovljivo analizo tovrstnih slik pri atomski ločljivosti se lahko poslužimo algoritmov za obdelavo slik. Magistrsko delo se fokusira na razvoj tovrstnih algoritmov, kjer je bilo glavno vodilo reciklirati drugje že uveljavljene koncepte ter jih prenesti v elektrokatalizo. Po uvodu v obravnavan problem sledi opis mikroskopije na identični lokaciji, simulacije slik in razvoja algoritmov za obdelavo slik. Slednje predstavlja jedro dela in obsega postopke predobdelave slik, določanje pozicij atomskih stolpcev, segmentacijo slike na strukturno različne dele in poravnavo slik na identični lokaciji pred in po nekem postopku. Algoritmi so bili razviti na realnih slikah katalizatorja z nanodelci iz zlitine platine in kobalta na ogljikovem nosilcu, testirani pa na simuliranih slikah idealiziranih modelov platinskih nanodelcev na ogljikovem nosilcu. Po pokazanem delovanju algoritmov na obeh tipih slik sledi uporaba rezultatov algoritmov na konkretnem primeru katalizatorja z nanodelci iz zlitine platine in kobalta ter komentar o prednostih in slabostih tovrstnega pristopa.

Keywords

elektronska mikroskopija;obdelava slik;elektrokataliza;nanodelci;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL FMF - Faculty of Mathematics and Physics
Publisher: [A. R. Kamšek]
UDC: 543.456
COBISS: 75421955 Link will open in a new window
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Downloads: 51
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Other data

Secondary language: English
Secondary title: Algorithms for image analysis of atomically resolved electron micrographs
Secondary abstract: Identical location scanning transmission electron microscopy is a method for materials characterization which enables imaging the same regions of interest in a material before and after a certain process. Utilizing this method for observing changes of hydrogen fuel cell catalysts in the form of metallic nanoparticles on carbon support enables a reliable assessment of their structure-stability relationship as changes can be observed at the atomic scale. For a faster, more objective and reproducible analysis of such images at atomic resolution, image analysis algorithms can be used. This master's thesis focuses on the development of such algorithms, particularly on taking advantage of concepts already in use in other fields and transferring them to electrocatalysis. After an introduction into the problem, identical location microscopy, image simulation, and image analysis algorithm development are described. The latter represents the core of this work and covers various preprocessing methods, determination of atomic column positions, segmentation of images into structurally different parts, and alignment of identical location images. The algorithms were developed on experimental images of a catalyst featuring platinum-cobalt alloy nanoparticles on carbon support, and tested on simulated images of idealized models of platinum nanoparticles on carbon support. After demonstrating the algorithms' performance on both types of images, their application on an actual example of a catalyst with platinum-cobalt alloy nanoparticles is shown and a discussion of advantages and disadvantages of this approach follows thereafter.
Secondary keywords: electron microscopy;image analysis;electrocalatysis;nanoparticles;
Type (COBISS): Master's thesis/paper
Study programme: 0
Thesis comment: Univ. v Ljubljani, Fak. za matematiko in fiziko, Oddelek za fiziko
Pages: 59 str.
ID: 13349321