Reports: ND1051719-ND10: New Strategies for the Preparation of Graphene Nanoribbons
Jean-Francois Morin, Universite Laval
The goal of our research with this project
funded by the PRF was to develop new strategies for the preparation of graphene
nanoribbons using the tools of organic chemistry. The idea of using solution
chemistry rather than well-known physical methods for the preparation of such
materials was to have better control over the size, the shape and chemical
nature of the resulting graphene nanoribbons to meet the requirement of the
electronics industry in terms of materials purity, uniformity and properties. The
methodology used to prepare graphene nanoribbons was not exactly the same we
described in the proposal. However, we can say for sure that our methodology is
by far superior in terms of synthetic feasibility and rapidity. Previous to
this grant, we have developed a method to efficiently prepare aryl-appended
polydiacetylenes (PDAs) for optical sensors applications. With the ACS-PRF
grant money, we decided to investigate these PDAs as starting materials for the
preparation of graphene nanoribbons. The initial hypothesis is that the
arylenyne moieties within the PDA scaffold could be cycloaromatized to form
fused aromatic systems (graphene nanoribbons) upon irradiation with UV light or
gentle heating (Figure 1).
Figure 1. Synthesis of graphene-type
materials from aryl-appended PDA
After one year and a half, we are
now at determining the exact chemical nature of the materials we obtained.
Although not perfect, the chemical structure of the graphene nanoribbons we
obtained present unique electronic and optical properties that could be
exploited in many applications. Moreover, we have undertaken the modification
of the chemical functions present on the nanoribbons in order to obtain new
electronic and optical properties.
In the first year of the grant, we
reported the synthesis of two-dimensional graphene-like materials from long
butadiyne-containing, reactive organic precursors (Figure 2).
Figure 2. Synthesis of graphene-like
materials from reactive precursors
In the second year of the grant, we
applied what we learned in the first year to different architectures. We
prepare one-dimension (nanotubes and wires) structures on which we made
different chemical modifications to change their properties. Among others, we
used thermal treatment on one- and two-dimensional materials to completely
graphitize their structure (Figure 3). Although we have not obtained the expect
results, the experiments allowed us to understand a great a deal about chemical
reactivity of PDA.
Figure 3. TEM imaging of pyrolyzed
cobalt-containing PDA-walled nanorods. The scales are: (a) 100 nm and (b) 20
nm.
The ACS-PRF New Direction grant has
had a great impact in my early career. The money I got accounted for a
significant part of all the grants I had from different sources in the past two
years. Only in the past year, it allows me to hire 3 graduate students to work
on the development of new methodologies for the preparation of graphene
nanoribbons and two-dimensional graphene-like materials. In only two years,
this project has become the main focus of my research group with 4 graduate
students now working on it full time. Without this money, I would not have
started this successful project. The students I have been able to hire with
this money got training in a highly hot topic and one of them is now a postdoc
fellow at Stanford University. Because this project is multidisciplinary, it
allows the student to learn different techniques, going from chemical synthesis
to materials characterization. With several papers published on
graphene-related materials, this project is undoubtedly a real success in term
of scientific production and advancement of scientific knowledge.
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