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Formation of cobalt oxide clusters on oxygen modified graphene

Schneider, Robin LU (2015) In Formation of cobalt oxide clusters on oxygen modified graphene FYSK01 20151
MAX IV Laboratory
Department of Physics
Abstract
Aim of this thesis is to study and characterize the formation of cobalt oxide clusters on graphene. The performed experiments consist of three different steps. First, a monolayer graphene film is grown with temperature programmed growth and chemical vapor deposition on an Iridium (111) single crystal surface. Second, the graphene film is exposed to oxygen radicals, which bind to the film and form clusters. In the last step, cobalt oxide was deposited onto the O-functionalized graphene film to form cobalt oxide clusters atop the oxygen clusters.\\
The evolution of the experiment is studied with x-ray photoelectron spectroscopy. The recorded data of the C 1s spectrum from the O-functionalization experiment are coherent with recently... (More)
Aim of this thesis is to study and characterize the formation of cobalt oxide clusters on graphene. The performed experiments consist of three different steps. First, a monolayer graphene film is grown with temperature programmed growth and chemical vapor deposition on an Iridium (111) single crystal surface. Second, the graphene film is exposed to oxygen radicals, which bind to the film and form clusters. In the last step, cobalt oxide was deposited onto the O-functionalized graphene film to form cobalt oxide clusters atop the oxygen clusters.\\
The evolution of the experiment is studied with x-ray photoelectron spectroscopy. The recorded data of the C 1s spectrum from the O-functionalization experiment are coherent with recently published literature on the same topic. The Ir 4f$_{7/2}$ suggests that 6.5\% of the carbon atoms are bound in an epoxy group. Furthermore the Ir 4f$_{7/2}$ spectra show exclude intercalataion of oxygen or cobalt oxide. Subsequent deposition of cobalt oxide on the O-functionalized graphene film leads to cobalt oxide in rocksalt structure containing Co$^{2+}$ ions. The ratio of cobalt oxide and the epoxy group is 1:1 which suggest the formation of cobalt oxide cluster onto the oxygen radicals. Nonetheless, further scanning tunneling microscopy experiments have to be performed to describe the stability, structure, size and coverage of these clusters. This is briefly discussed in the outlook. (Less)
Popular Abstract
Many problems in our modern society would be solved, if we could mimic the chemical processes in nature. In the photosynthesis of plants light is absorbed and converted into chemical energy in the form of organic molecules through a complex chemical process. An important step of this chemical reaction is the splitting of water (H20) into hydrogen (H2) and oxygen (O2). Since there is plenty of water on earth, an efficient way to mimic nature's photocatalytic water could provide us with fuel (H2) and stop the greenhouse effect by using the energy of the sun. The splitting of water requires however a very efficient catalysts.

Catalysts, are well known for their usage in cars, where they convert toxic gases(e.g. CO and NO) into less toxic... (More)
Many problems in our modern society would be solved, if we could mimic the chemical processes in nature. In the photosynthesis of plants light is absorbed and converted into chemical energy in the form of organic molecules through a complex chemical process. An important step of this chemical reaction is the splitting of water (H20) into hydrogen (H2) and oxygen (O2). Since there is plenty of water on earth, an efficient way to mimic nature's photocatalytic water could provide us with fuel (H2) and stop the greenhouse effect by using the energy of the sun. The splitting of water requires however a very efficient catalysts.

Catalysts, are well known for their usage in cars, where they convert toxic gases(e.g. CO and NO) into less toxic ones (CO2 and N2). Catalysts that help us with the splitting of water are, however, made of rare and expensive metals like Platinum. Hence, the production of those is not efficient. Scientist therefore search for new improved and cheaper alternatives. As catalysts often have a complex structure, they are difficult to characterize, simplified model catalysts are therefore used instead.

Such a model system should contain several ordered collections of cobalt oxide particles. The recently discovered material graphene brings along these properties. Grown on a metal it forms a mesh, which can be imagined as a landscape consisting of alternating hills and valleys and it is possible to deposit cobalt oxide atoms only in the valleys of the mesh.

The deposition of ordered cobalt oxide clusters and their structure was investigated in my work and it contributes to the understanding of cobalt oxide catalyst that might be used as photocatalysts for the splitting of water in the future. (Less)
Please use this url to cite or link to this publication:
author
Schneider, Robin LU
supervisor
organization
course
FYSK01 20151
year
type
M2 - Bachelor Degree
subject
keywords
Graphene, Cobalt oxide, clusters, STM, XPS, LEED, moire pattern, oxygen functionalized graphene, rocksalt, spinel, Iridium, Ir(111), monolayer graphene, oxygen radicals, carbon
publication/series
Formation of cobalt oxide clusters on oxygen modified graphene
language
English
id
7448776
date added to LUP
2015-08-13 18:05:22
date last changed
2015-08-13 18:05:22
@misc{7448776,
  abstract     = {Aim of this thesis is to study and characterize the formation of cobalt oxide clusters on graphene. The performed experiments consist of three different steps. First, a monolayer graphene film is grown with temperature programmed growth and chemical vapor deposition on an Iridium (111) single crystal surface. Second, the graphene film is exposed to oxygen radicals, which bind to the film and form clusters. In the last step, cobalt oxide was deposited onto the O-functionalized graphene film to form cobalt oxide clusters atop the oxygen clusters.\\
The evolution of the experiment is studied with x-ray photoelectron spectroscopy. The recorded data of the C 1s spectrum from the O-functionalization experiment are coherent with recently published literature on the same topic. The Ir 4f$_{7/2}$ suggests that 6.5\% of the carbon atoms are bound in an epoxy group. Furthermore the Ir 4f$_{7/2}$ spectra show exclude intercalataion of oxygen or cobalt oxide. Subsequent deposition of cobalt oxide on the O-functionalized graphene film leads to cobalt oxide in rocksalt structure containing Co$^{2+}$ ions. The ratio of cobalt oxide and the epoxy group is 1:1 which suggest the formation of cobalt oxide cluster onto the oxygen radicals. Nonetheless, further scanning tunneling microscopy experiments have to be performed to describe the stability, structure, size and coverage of these clusters. This is briefly discussed in the outlook.},
  author       = {Schneider, Robin},
  keyword      = {Graphene,Cobalt oxide,clusters,STM,XPS,LEED,moire pattern,oxygen functionalized graphene,rocksalt,spinel,Iridium,Ir(111),monolayer graphene,oxygen radicals,carbon},
  language     = {eng},
  note         = {Student Paper},
  series       = {Formation of cobalt oxide clusters on oxygen modified graphene},
  title        = {Formation of cobalt oxide clusters on oxygen modified graphene},
  year         = {2015},
}