Surfactant-assisted liquid-phase shear exfoliation of graphene and subsequent thin film fabrication by spray deposition

G2 Master’s thesis, polytechnic Master’s thesis


Internal Authors/Editors


Publication Details

List of Authors: Saara Elina Sirkiä
Publisher: Åbo Akademi University
Place: Turku
Publication year: 2018
Number of pages: 64


Abstract

Graphite is the bulk form and source material of graphene, the versatile
nanomaterial which consists of a single atomically thin sheet of carbon
molecules in a honeycomb structure. It has unique properties, such as
high elasticity, excellent optical properties and high electron
mobility. The outstanding properties of graphene has made it the object
of extensive research and a potential component for novel applications
in several scientific fields, such as sensing technology. The scientific
interest is high not just for graphene, the monolayer sheet, but also
for graphene-like materials which are a common by-product of graphene
production or otherwise resemble graphene by properties or structure.
Graphene can be produced in numerous ways. This thesis investigates
surfactant-assisted liquid-phase shear exfoliation which derives from
mechanical exfoliation.

In the thesis, graphene was exfoliated from graphite in an aqueous
surfactant-graphite suspension with a rotor-stator homogeniser. The
graphene dispersion was separated with centrifugation and the graphene
concentration was determined with ultraviolet-visible (UV-Vis)
spectroscopy. The graphene samples were examined with scanning electron
microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Thin
graphene films were produced with spray deposition and the electrical
conductivity of the films was determined by measuring the electrical
resistivity of the films.

Both commercial graphite and graphite excavated from Finnish soil
were used to study the exfoliation, four different graphite samples in
total. The graphite samples differed in particle size and purity. The
Finnish graphite was excavated in Haapamäki, Finland, and purified with
froth flotation and chemical leaching. The quality and yield of both the
commercial graphene samples and the Finnish graphene were compared. The
purity level of graphite was shown not to affect the graphene yield
significantly, as opposed to the graphite particle size, which showed an
effect on the yield. The electrical conductivity of the graphene thin
films was found to be on a good level, considering the method used to
produce the thin conductive components.


Keywords

Graphene, natural graphite, surfactant-assisted liquid-phase shear exfoliation, thin film fabrication

Last updated on 2020-07-07 at 05:53