Carbon Materials and Tubes & Rods of Non-Carbon Materials Flashcards
How large is the C60 molecule?
How many 5-rings and 6-rings of carbon atoms does it contain?
What is the approximate C-C bond distance?
- C60: 7.0 Å
- 12 five-rings, 20 six-rings
- C-C bond distance: 1.41 Å
Describe the chemical bonding in graphene and graphite.
- Graphene (single layer): sp2-sigma bonds and pi-bonds, which are responsible for the metallic conductivity
- Graphite: vdW-bonding between layers
Consider lecture slides and compare the elctronic band structure of C (diamond), Si and Ge. N-doping of diamond gives yellow crystals. How will you explain that based on the band structure?
Nitrogen will acts as a donor for carbon (brings
Give chemical formulas for some graphene analogous materials. How do the electronic properties of BN differ from those of graphene?
- h-BN
- BCN2
- BC2N
BN is an insulator
Describe how fullerenes and carbon nanotubes are formed in an arc reactor. Why is cooling of the reactor walls reaquired?
Arc discharge in inert protection gas
Cooling of walls are important for any fullerenes being made, as the formed fullerenes would decompose if not.
Describe synthesis routes of graphene.
- Exfoliation
- Sonication in a liquid medium followed by centrifugation
- Bottom-up synthesis based on sugars
- Reduction of ethanol with sodium followed by pyrolysis
- Catalytic CVD processes etc
- Reduction of graphene oxide
What is graphene oxide? Describe synthesis route, and its electronic properties. Which types of C-C bonds are oxidized in the synthesis process? How can the various functional groups of the GO be investigated/determined?
Graphene where the
- Spectroscopy IR/RAMAN
How can RGO be obtained? Which properties makes RGO attractive for use e.g. as an additive to electrode materials for Li-ion batteries?
- Heat graphene to 180-220 celsius
- Reduce with hydrazine
- Use Cu catalyst + hydrazine
Additive: Good electronic conductivity
What is understood with pillaring of RGO (GOpr)? Why is RGO considered of potential interest in catalysis?
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Comment on the mechanical strength of carbon nanotubes. How will defects affect these properties? What is understood by topological defects in graphene?
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Describe the difference between multiwall tubes and a scroll. Do both of these types of structures occur both for carbon materials and e.g. V-based oxide materials? How can you experimentally verify which of these situations do occur for a given sample - scroll versus tube?
- Multiwall: Tubes inside tubes
- Scroll: Rolled up sheets (does not exist in graphene)
Describe the building principle of different variants of carbon nanotubes. Are the systematic correlations between building principle and electronic properties of the CNT?
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What is the difference between armchair and zig-zag CNT structures?
It’s how the CNT is rolled up.
Describe possible low-temperature chemical synthesis routes to CNTs. What is the Boudouard reaction? In which organic/inorganic compounds can we find reactive C-atoms or C-C dimers?
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Describe carbon cones. Why do they form with specific opening angles for the cone?
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