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Improving water dispersibility of non-covalent functionalized reduced graphene oxide with L-tryptophan via cleaning oxidative debris

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Maoyong Zhi at Civil Aviation Flight University of China
Maoyong Zhi
Wanxia Huang at Sichuan University
Wanxia Huang
Qiwu Shi at Sichuan University
Qiwu Shi
Ke Ran
Ke Ran
Ke Ran
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Abstract and Figures

Non-covalent functionalized reduced graphene oxide (rGO) with l-tryptophan was rapidly fabricated by reducing graphene oxide (GO), using l-ascorbic acid as reducer under microwave heating. Atomic force microscope, scanning electron microscope, ultraviolet–visible spectroscopy, X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy were employed to investigate the morphologies and structures of the samples. The average particle sizes and zeta potentials of rGO were measured by means of dynamic light scattering spectroscopy. Furthermore, the maximum dispersibility of rGO dispersion was calculated from Lambert–Beer law. It was shown that oxidative debris of GO were cleaned after ammonia wash process, and ultimately improving the water dispersibility through enhancing the π–π interaction between l-tryptophan molecules and rGO sheets. The maximum dispersibility of the functionalized rGO dispersion with cleaning oxidative debris was increased by 95 % (from 0.44 to 0.86 mg mL−1) compared to that without cleaning oxidative debris. This investigation proposed an effective method to fabricate the non-covalent functionalized rGO, as well as the method to improve its water dispersibility.
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Improving water dispersibility of non-covalent functionalized
reduced graphene oxide with L-tryptophan via cleaning oxidative
debris
Maoyong Zhi
1
•Wanxia Huang
1
•Qiwu Shi
2
•Ke Ran
1
Received: 21 November 2015 / Accepted: 18 March 2016 / Published online: 22 March 2016
ÓSpringer Science+Business Media New York 2016
Abstract Non-covalent functionalized reduced graphene
oxide (rGO) with L-tryptophan was rapidly fabricated by
reducing graphene oxide (GO), using L-ascorbic acid as
reducer under microwave heating. Atomic force micro-
scope, scanning electron microscope, ultraviolet–visible
spectroscopy, X-ray diffraction, Raman spectroscopy and
Fourier transform infrared spectroscopy were employed to
investigate the morphologies and structures of the samples.
The average particle sizes and zeta potentials of rGO were
measured by means of dynamic light scattering spec-
troscopy. Furthermore, the maximum dispersibility of rGO
dispersion was calculated from Lambert–Beer law. It was
shown that oxidative debris of GO were cleaned after
ammonia wash process, and ultimately improving the water
dispersibility through enhancing the p–pinteraction
between L-tryptophan molecules and rGO sheets. The
maximum dispersibility of the functionalized rGO disper-
sion with cleaning oxidative debris was increased by 95 %
(from 0.44 to 0.86 mg mL
-1
) compared to that without
cleaning oxidative debris. This investigation proposed an
effective method to fabricate the non-covalent functional-
ized rGO, as well as the method to improve its water
dispersibility.
1 Introduction
Graphene, a two-dimensional honeycomb sp
2
carbon
nanostructure, has attracted great interest in recent years
due to its intriguing thermal, electrical and mechanical
properties [1–4]. Chemical reduction of graphene oxide
(GO) is one of the most effective methods for the large-
scale production of graphene among various fabrication
methods [5,6]. However, there are only few functional
groups in reduced GO (rGO), leading to irreversible
aggregation or even restacking to graphite through strong
p–pstacking or van der Waals interactions in water and
organic solvents [7]. In recent years, surface functional-
ization is an effective method to improve the water dis-
persibility of rGO. Non-covalent functionalized rGO via
the p–pstacking is fascinating because of less destruction
on the structure and the electronic network of graphene [8,
9]. Compared with conventional heating methods, micro-
wave heating has many advantages because it has a more
homogeneous heating process and can accelerate reaction
rates [10,11].
Recently, Rourke et al. [12] and Thomas et al. [13]
revealed that the surface of GO sheets prepared by exfo-
liating graphite oxide was covered with many highly oxi-
dized polyaromatic carboxylated fragments by non-
covalent interactions. Li et al. [14] found that the con-
centration of graphene suspension would be improved by
non-covalent functionalization with a large aromatic sta-
bilizer (sodium perylenetetracarboxylate), and proposed a
mechanism that the preliminary base wash of GO for
removing carbonaceous adsorbates effectively promoted
the adsorption of stabilizer onto graphene via p–pinter-
action. Coluci et al. [15] studied the influence of oxidative
debris on the non-covalent interaction of GO sheets with
1-nitropyrene, and the results showed that GO samples
&Wanxia Huang
huangwanxia@scu.edu.cn
1
College of Materials Science and Engineering, Sichuan
University, Chengdu 610064, People’s Republic of China
2
College of Physical Science and Technology, Sichuan
University, Chengdu 610064, People’s Republic of China
123
J Mater Sci: Mater Electron (2016) 27:7361–7368
DOI 10.1007/s10854-016-4708-x
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
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