A peel-off graphene sheet fabricated from camphor

By Susheela Srinivas

Bengaluru, August
19 (India Science Wire): Graphene, a recently discovered wonder material, is
increasingly sought after for its superior electrical, thermal, optical and
mechanical properties. It finds use in the manufacture of optoelectronic
devices such as detectors, sensors and solar cells.

Graphene is made
up of one-atom-thick, honeycomb-like structure of carbon atoms.  A significant challenge faced by scientists
is the fabrication of large-area graphene sheets for devices. Finding a ‘green’
source for the carbon atoms is another hurdle.

Indian
researchers have now developed a new method to fabricate graphene sheets from
camphor — a readily available ingredient often used in religious rituals.

“Camphor is a
plant product with abundant carbon elements required to derive graphene. All it
needs is restructuring — breaking and making of chemical bonds— of the carbon
atoms.  So we explored the possibility
and achieved this rearranging of elements of camphor to get graphene mono-layers,”
said Dr Indrajit Mukhopadhyay, lead researcher of the study at the Pandit
Deendayal Petroleum University, while speaking to India Science Wire.

   Group of researchers at
Pandit Deendayal Petroleum University

Camphor was
subjected to thermo-chemical process called pyrolysis and then deposited
by chemical vapour deposition technique on a commercially available 25-micron
thick copper foil. Camphor was heated and its vapours were sent into a tubular
furnace and heated further to 1020 degree Celsius. The vapour was then treated
with nitrogen and hydrogen gases to eliminate unwanted components of camphor.

Copper was used
as substrate since carbon has negligible reactivity to it. Moreover, copper
itself acts as a catalyst for restructuring of carbon atoms, which were
deposited in a monolayer over 1inch x 1inch foil. The novelty of the method lay
in the recoverability of the graphene sheet. “With our technology, the
fabricated graphene layer can be extracted and transferred to other substrates
depending on the application,” added Dr Mukhopadhyay.

Once the graphene
layer is developed on the foil, copper can be removed by chemical methods,
leaving behind a pure monolayer of graphene. This layer can be suspended in a
solvent and transferred to other substrates like aluminum, silica or a polymer,
as per the device requirements, he explained.

The graphene
sheets were subjected to rigorous laboratory tests to evaluate the structural
and morphological parameters. The results established its uniformity and
robustness. “We have further demonstrated its use by utilising it in a highly
sensitive infra-red detector”, he said.

Besides
Indrajit Mukhopadhyay, the research team included Harsh A Chaliyawala, Roma
Patel and Abhijit Ray from Pandit Deendayal Petroleum University, Gujarat; and
Narasimman Rajaram from CSIR-National Institute for Interdisciplinary
Science and Technology,
Thiruvananthapuram. The study results have been
published in journal ACS Omega.

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