Reducing graphene oxide using hydroiodic acid fumes and low temperature annealing for enhanced electrical conductivity

Abstract

In this work, a novel hybrid technique for reduction of graphene oxide is explored. The hybrid technique involves chemical reduction of graphene oxide coated over oxidized silicon substrate, by minimal exposure to HI acid fumes followed by low temperature thermal annealing under vacuum environment. Observations have shown improved conductivity as compared to other hybrid techniques and low temperature thermal annealing technique.

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Graphene Technology (2020) 5:19–25
https://doi.org/10.1007/s41127-020-00030-4
ORIGINAL ARTICLE
Reducing graphene oxide using hydroiodic acid fumes andlow
temperature annealing forenhanced electrical conductivity
G.Shruthi1· G.Baishali2· V.Radhakrishna3· PayalVerma1
Received: 26 February 2019 / Revised: 26 March 2020 / Accepted: 7 April 2020 / Published online: 23 April 2020
© Springer Nature Switzerland AG 2020
Abstract
In this work, a novel hybrid technique for reduction of graphene oxide is explored. The hybrid technique involves chemical
reduction of graphene oxide coated over oxidized silicon substrate, by minimal exposure to HI acid fumes followed by low
temperature thermal annealing under vacuum environment. Observations have shown improved conductivity as compared
to other hybrid techniques and low temperature thermal annealing technique.
Keywords Reduced graphene oxide· Thermal annealing· Hybrid reduction· XRD· Raman spectroscopy· SEM·
Electrical conductivity
1 Introduction
Recently graphene has attracted a lot of attention due to
its remarkable electronic properties and its applications
in various fields including electronics and optoelectronics
[1–4]. Graphene is a two-dimensional sheet of carbon atoms
arranged in a honeycomb lattice. It is extremely light weight,
has excellent mechanical and electrical properties, which
makes it a suitable candidate for portable devices. Many
people have reported synthesis of graphene monolayer by
Chemical Vapor Deposition (CVD) technique for different
electronic applications [5–7]. CVD is a costly process and is
difficult to synthesize for large area electronic devices. Gra-
phene, when prepared by mechanical exfoliation is known
to have best quality but the size of the obtained flakes and
its controllability is very low [8]. Graphene can also be pre-
pared by reducing graphene oxide (GO) [9–14]. This method
uses chemical route and hence is cost effective with higher
yield. However, reduction of graphene on large scale with
controlled parameters over various kinds of substrates is a
major challenge [3]. Conductivity of reduced graphene oxide
(rGO) is not comparable to that of pristine graphene but can
be improved by using different routes of reduction of GO
[9].
There are different routes to reduce GO to achieve
maximum electrical conductivity [9, 10] of which thermal
reduction [11] and chemical reduction [12–14] routes are
widely used. It is well known that thermal reduction gives
better electrical conductivity than chemical or electrochemi-
cal methods [15]. In thermal reduction, GO is exposed to
high temperature of around 1050°C in a vacuum furnace
or furnace filled with inert gas namely nitrogen or argon.
Sometimes the furnace is filled with a mixture of two gases
to avoid the burning of GO [16]. This method is useful for
bulk production of rGO, but the main limitation of this
method is its reduced yield and higher defect density [17].
There are literatures which shows the reduction of GO by
low temperatures around 90–300°C as well [18–21]. In
this method, hydroxyl and epoxy groups are removed and
restored with C=C sp2 bonds. The chemical reduction of
GO uses strong reducing agents to remove the oxygen con-
taining groups from GO. Hydrazine and its derivatives like
hydrazine hydrate and dimethyl hydrazine are universally
accepted good chemical reagents to reduce GO [22]. Reduc-
ing by this method is simple and gives good electrically
conducting rGO. However, hydrazine groups tend to leave
C–N group on rGO during reduction process and also it is
a highly toxic reagent. Thus, development of new reduction
methods of GO that are eco-friendly, low cost and feasible
* G. Baishali
baishaligarai-phy@dsu.edu.in
1 Department ofElectronics andCommunication Engineering,
Dayananda Sagar University, Bangalore, India
2 Department ofPhysics, Dayananda Sagar University,
Bangalore, India
3 Space Astronomy Group, U R Rao Satellite Centre,
Bangalore, India
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