Construction of Nanostructured Cobalt Oxide Thin Films

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Construction of Nanostructured Cobalt Oxide Thin
Films

• Jordan Maron
• Jamie Neilson
• Daniel Morse
• Biomolecular Science and Engineering

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Why Study Cobalt Oxide?

• Energy application photocatalytic water
  splitting generating hydrogen fuel from light
• Enabled by
• Atomic structures with Co(III), e.g. Co3O4
• Morphology with high surface area

Cobalt Oxide Powder
Cobalt Oxide Atomic Structure
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Cobalt Oxide Background

• Usually produced with irregular morphology and
  microstructure
• Hard to characterize
• Our method of synthesis allows for control of
  morphology on the nano scale
• More useful for proposed applications

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My Project Goal

• Find which cobalt counter ion and annealing
  temperature produce the most crystalline cobalt
  oxide sample with the highest specific surface
  area derived from a nanostructured architecture

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Experimental Methods

• Synthesize cobalt hydroxide by reacting various
  CoAx precursors with ammonia via vapor diffusion
• Cobalt chloride
• Cobalt perchlorate
• Cobalt sulfate
• Cobalt iodide
• Sample Treatment
• One substrate left as is
• One put in 180C oven
• One put in 500C furnace
• One put in 800C furnace
• Analysis and characterization

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Experimental Methods Visual
Start
Finish
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Characterization

• Two machines are used
• X-Ray diffractometer
• Scanning electron microscope
• Used to identify compound and analyze its
  morphology

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X-Ray Diffraction

• Control Alfa Aesar cobalt oxide

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X-Ray Data Continued

• Cobalt chloride precursor

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X-Ray Data Continued

• Cobalt perchlorate precursor

Both Cobalt Oxide
Amorphous
Cobalt Hydroxide
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Scanning Electron Microscopy

• Control Alfa Aesar cobalt oxide

Relatively unstructured morphology
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SEM Data Continued

• Cobalt chloride precursor

Individual platelets at all temperatures
Notice strange Swiss- cheese platelet morphology
in 900C sample
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SEM Data Continued
Varying morphology at all temperatures

• Cobalt perchlorate precursor

Very interesting porous nanostructure -
cause unknown
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Results Summary
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Conclusions

• Both counter ion and annealing temperature
  determine material properties
• Determines morphology
• Crystal orientation
• Atomic structure
• Larger counter ions decrease annealing
  temperature needed and increases microporosity

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Future Exploration

• Perform a second trial with each precursor to see
  whether or not the results can be reproduced or
  improved
• Investigate causes of certain morphologies
• Test performance of our cobalt oxide and compare
  to that of commercially available cobalt oxide
• Analyze with transmission electron microscope
• Measure specific surface area

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Reflections

• I got a taste of what it is like to do graduate
  research in a real laboratory
• I confirmed for myself that pursuing a career in
  the sciences seems to be the right path for me
  take
• I loved getting to use all the really fancy
  equipment

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Acknowledgements

• Jamie Neilson and Birgit Schwenzer for being my
  mentors
• Professor Daniel Morse for allowing me to work in
  his department
• California NanoSystems Institute, Institute for
  Collaborative Biotechnologies, Department of
  Energy, and National Science Foundation for
  funding the research
• Lubi, Anthony, and Herb for organizing the
  program

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Construction of Nanostructured Cobalt Oxide Thin
Films

• Jordan Maron
• Jamie Neilson
• Daniel Morse
• Biomolecular Science and Engineering

20
X-Ray Data

• Cobalt sulfate precursor

Notice consistency between trials
Cobalt oxide confirmed in matching 800C
samples 500C contained one cobalt oxide peak As
is and 180C shown to contain cobalt hydroxide
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SEM Data

• Cobalt sulfate precursor

Globule Morphology
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X-Ray Data

• Cobalt iodide precursor

Co3O4
Co3O4
Disordered Co3O4
Cobalt Hydroxide
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SEM Data

• Cobalt iodide precursor

Morphology resembles that of the 800C sulfate
sample
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TGA Data
Chloride Sample
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TGA Data
Perchlorate Sample
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TGA Data
Sulfate Sample
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TGA Data
Iodide Sample