Q.  Which of the following is/are true?

1) Graphene is an extremely thin three-dimensional form of carbon.
2) In aqueous solution, graphene can bind negatively charged ions.

- Published on 12 Apr 16

a. Only 1
b. Only 2
c. Both 1 and 2
d. Neither 1 nor 2

ANSWER: Neither 1 nor 2
  • Graphene is a two-dimensional form of carbon in which the atoms are bonded into a honeycomb arrangement.
  • It can readily be prepared by the oxidation, exfoliation and subsequent reduction of graphite.
  • Graphene is characterised by its unusual electronic properties: It conducts electricity and is rich in electrons that can move freely across the entire layer.
  • In aqueous solution, graphene can bind positively charged ions with its electrons. This property is used in graphene-based processes to remove lead ions and organic dyes from solutions.
  • This phenomenon inspired researchers to use graphene electrodes to obtain power from the impact of raindrops.
  • Raindrops are not pure water. They contain salts that dissociate into positive and negative ions. The positively charged ions, including sodium, calcium and ammonium ions, can bind to the graphene surface.
  • At the point of contact between the raindrop and the graphene, the water becomes enriched in positive ions and the graphene becomes enriched in delocalised electrons.
  • This results in a double-layer made of electrons and positively charged ions, a feature known as a pseudocapacitor. The difference in potential associated with this phenomenon is sufficient to produce a voltage and current.

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