Growth of PdO on Pd(100)

Abstract

This thesis explores the growth of palladium oxide (PdO) on palladium(100) surfaces, focusing particularly on how different environmental conditions affect the formation and stability of various PdO orientations rellative to the Pd substrate. The motivation of the project is that catalytic oxidation of methane, is believed to be strongly dependent on the surface structure of the involved catalyst. Gaps remain in understanding how specific PdO surface planes form and stabilize under different conditions and how these planes influence catalytic activity for methane oxidation.

The aim of this study was to understand the formation processes of PdO surface planes such as PdO(100) and PdO(101) under varying temperatures and oxygen pressures. Using grazing incidence X-ray diffraction (GIXRD), this research systematically analyzed how these surfaces respond to changes in environmental conditions, with a hypothesis that different temperatures and oxygen pressures promote the formation of a variety of PdO planes. The methodology involved detailed GIXRD experiments conducted at temperatures ranging from 250°C to 400°C, with oxygen pressures from 2 × 10−4 mbar to 100 mbar.

This approach allowed for observations of the formation of PdO planes on the Pd(100) substrate, providing data on their structural configurations. Findings reveal that higher temperatures and pressures indeed facilitate the formation of diverse PdO planes. Higher temperature also appears to facilitate the formation of multiple different planes on the same surface. At low temperatures we found the PdO(201) orientation, a result not previously documented in previous literature.

This study contributes to the field of catalysis by attempting to detail the conditions under which different PdO planes form and by highlighting the potential catalytic differences of these planes. The hope is with these gained insights along with future research to develop more effective catalysts particularly for methane oxidation.

Popular Abstract

Harnessing Palladium Oxide

In the intricate world of materials science, understanding how surfaces react and change under different conditions can lead to significant advancements in various technologies. One such material of recent research is palladium oxide (PdO) films, especially when these films are formed on special palladium surfaces. These thin layers of PdO may improve the catalytic processes, in other words transforming one material into another. The transformation in question we wish to improve is turning methane-a potent greenhouse gas into water and carbon dioxide-a much less potent greenhouse gas.

This study explores the formation and behavior of PdO films under varying environmental conditions. Further we explore how different temperatures and oxygen pressures affect the growth and stability of various PdO surface planes, each with its unique properties and potential catalytic activities.

The research focuses on the formation processes of specific PdO surface planes. By employing surface X-ray diffraction (SXRD), the study observes the structure of the material on an atomic level, meaning that we are looking at the order in which the smallest building blocks of the material are arranged. The study systematically analyzes how these surfaces respond to changes in temperature and oxygen pressure. Previous research suggests that different conditions promote the formation of different PdO orientations, likely leading to variations in catalytic efficiency.

The findings of this study are both intriguing and promising. Higher temperatures and increased oxygen pressures were found to facilitate the formation of diverse PdO planes. Notably, a PdO plane, which has not been documented in previous literature, appeared with unexpected prevalence and stability. This discovery suggests that certain environmental conditions can favor the formation of specific PdO planes, which could be crucial for their catalytic performance.

These results are significant as they contribute to a better understanding of PdO catalysis, offering new insights that could lead to more efficient transformation processes of methane. Knowing which PdO surfaces form under specific conditions helps tailor these transformations more effectively, optimizing their performance for industrial applications.

• author: Bramer, Isac
• supervisor: Johan Gustafson; Hanna Sjö
• organization: Department of Physics; Synchrotron Radiation Research
• course: FYSK04 20241
• year: 2024
• type: M2 - Bachelor Degree
• subject: Physics and Astronomy
• language: English
• id: 9170691
• date added to LUP: 2024-08-12 09:00:06
• date last changed: 2024-08-12 09:00:06