Advanced

CO induced faceting of Rh(553)

Lai, Ka Sin LU (2015) FYSK01 20151
Department of Physics
Synchrotron Radiation Research
Abstract (Swedish)
We have investigated the CO induced faceting of a Rh(553) surface using
Scanning Tunneling Microscope (STM), Low Energy Electron Diffraction
(LEED) and Auger Electron Spectroscopy (AES). The sample was exposed to
a CO pressure of 1x10^-3 mbar, at different sample temperatures. The experiment
was performed in the STM lab at the division of Synchrotron Radiation
Research at Lund University. According to a recent surface X-ray diffraction
study 1, the Rh(553) was reshaped into (110) and (111) facets, under CO rich
reaction conditions for catalytic CO oxidation, in pressures of 0.1-300 mbar. In
this project we tried to find if the faceting can also be found by exposure to
pure CO at a lower pressure. The main result of the CO... (More)
We have investigated the CO induced faceting of a Rh(553) surface using
Scanning Tunneling Microscope (STM), Low Energy Electron Diffraction
(LEED) and Auger Electron Spectroscopy (AES). The sample was exposed to
a CO pressure of 1x10^-3 mbar, at different sample temperatures. The experiment
was performed in the STM lab at the division of Synchrotron Radiation
Research at Lund University. According to a recent surface X-ray diffraction
study 1, the Rh(553) was reshaped into (110) and (111) facets, under CO rich
reaction conditions for catalytic CO oxidation, in pressures of 0.1-300 mbar. In
this project we tried to find if the faceting can also be found by exposure to
pure CO at a lower pressure. The main result of the CO exposure, however, is
a roughening of the surface. The roughening process is independent on the conditions we performed and the resulting surface consists of a signficant amount
of kinked steps and areas of various step size. Local areas of (110) surface is
observed, but no systematic change of areas as found in ref. 1.

1 Chu Zhang, Edvin Lundgren, Per-Anders Carlsson, Olivier Balmes, Anders
Hellman, Lindsay R Merte, Mikhail Shipilin, Willem Onderwaater, and
Johan Gustafson. Faceting of rhodium (553) in realistic reaction mixtures
of carbon monoxide and oxygen. The Journal of Physical Chemistry C,
2015. (Less)
Popular Abstract
My bachelor thesis deals with the change of Rhodium (Rh) stepped surface under pure carbon monoxide exposure, which will help the understanding of it as a catalyst of carbon monoxide oxidation.

Catalysts are widely used in different areas and industries as catalysis can help accelerating chemical reactions without itself being consumed. Rh is a metal catalyst used in the oxidation of CO to CO2. This oxidation can be used in cars to clean up the exhaust gas and also in other chemical industries. In general, it helps reducing the pollution gas to improve the environment.

Stepped surface is one of the solutions to improve the activity of the catalysts as it can lower the barrier of the chemical reaction. Rh(553) is a stepped surface... (More)
My bachelor thesis deals with the change of Rhodium (Rh) stepped surface under pure carbon monoxide exposure, which will help the understanding of it as a catalyst of carbon monoxide oxidation.

Catalysts are widely used in different areas and industries as catalysis can help accelerating chemical reactions without itself being consumed. Rh is a metal catalyst used in the oxidation of CO to CO2. This oxidation can be used in cars to clean up the exhaust gas and also in other chemical industries. In general, it helps reducing the pollution gas to improve the environment.

Stepped surface is one of the solutions to improve the activity of the catalysts as it can lower the barrier of the chemical reaction. Rh(553) is a stepped surface which consists of five-atom-wide flat terraces separated by steps (Figure is shown at the right). According to a previous study, the surface is found to undergo a systemic change of the surface under CO rich condition, which it reshapes into large areas of denser-stepped surface and large areas of flat area.

This experiment is to find if this reshaping can still be formed under CO pure condition with lower pressure. The main result of the CO exposure, however, is a roughening of the surface. The step edges become wavy and the step size is varied. The roughening process is independent on the conditions we performed. Small local areas of denser-stepped surface is observed, but no large areas as found in the previous study.

Further study is needed to be done to know more about the dynamics of the roughening process and why the observation in the previous study was not found. More understanding of the stepped-surfaced catalyst can help to analyze and even improve the behavior of the real-life catalysts used in the industries. (Less)
Please use this url to cite or link to this publication:
author
Lai, Ka Sin LU
supervisor
organization
course
FYSK01 20151
year
type
M2 - Bachelor Degree
subject
language
English
id
7359407
date added to LUP
2015-08-21 11:43:53
date last changed
2015-08-21 11:43:53
@misc{7359407,
  abstract     = {We have investigated the CO induced faceting of a Rh(553) surface using
Scanning Tunneling Microscope (STM), Low Energy Electron Diffraction
(LEED) and Auger Electron Spectroscopy (AES). The sample was exposed to
a CO pressure of 1x10^-3 mbar, at different sample temperatures. The experiment
was performed in the STM lab at the division of Synchrotron Radiation
Research at Lund University. According to a recent surface X-ray diffraction
study 1, the Rh(553) was reshaped into (110) and (111) facets, under CO rich
reaction conditions for catalytic CO oxidation, in pressures of 0.1-300 mbar. In
this project we tried to find if the faceting can also be found by exposure to
pure CO at a lower pressure. The main result of the CO exposure, however, is
a roughening of the surface. The roughening process is independent on the conditions we performed and the resulting surface consists of a signficant amount
of kinked steps and areas of various step size. Local areas of (110) surface is
observed, but no systematic change of areas as found in ref. 1.

1 Chu Zhang, Edvin Lundgren, Per-Anders Carlsson, Olivier Balmes, Anders
Hellman, Lindsay R Merte, Mikhail Shipilin, Willem Onderwaater, and
Johan Gustafson. Faceting of rhodium (553) in realistic reaction mixtures
of carbon monoxide and oxygen. The Journal of Physical Chemistry C,
2015.},
  author       = {Lai, Ka Sin},
  language     = {eng},
  note         = {Student Paper},
  title        = {CO induced faceting of Rh(553)},
  year         = {2015},
}