Graphene Oxide and Reduced Graphene Oxide as Nanofillers …
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aspect, leading to the higher permeability. The prepared composite with 0.067%
loaded GO showed double peak power densities compared to the pristine N212 in
direct formic acid, ethanol, and methanol fuel cells. The exact mass fraction of the
GO on the composite membranes was obtained to be 2.53 wt%. The well-aligned
thin top layer of GO contributed to the ideal fuel cell performance.
3 Characterization of Nanocomposite Membranes
The prepared nanocomposite membranes are characterized by various instrumental
methods to study the change in physiochemical properties and structure of the
membranes, which is caused by embedding GO or rGO into them. The Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), X-ray
Diffractometer (XRD), and Atomic Force Microscope (AFM) are typically used for
the morphology characterization, whereas X-ray Photoelectron Spectroscope (XPS)
and Fourier transform infrared (FTIR) spectroscope are commonly applied for functional group detection. Consequently, in order to study the effect of the surface
charge of the nanocomposite membrane, Zeta potential analyses are used. The contact
angle studies are employed to evaluate the surface hydrophilicity of the nanocomposite membranes. Thermogravimetric analysis (TGA) can also be used to measure
the weight loss and to detect the possible functionalized state of nanocomposite
membrane. At last, the mechanical stability of the membranes is measured by tensile
tests.
3.1 Membrane Morphology Analysis
(a) SEM Analysis
The cross-section morphologies and structure of the prepared nanocomposite
membranes are examined through SEM analyses. To make the membranes electrically conducting, the membrane samples are cut into small pieces and then
submerged in liquid nitrogen. Then sputtering of conductive metals (e.g. gold, platinum, cadmium, etc.) is used to coat on the cross-sectional layer. The acquisition
of cross-sectional images of the membranes is done in very high vacuum conditions [100–103]. Ganesh et al. [38] recorded the cross-sectional SEM images of the
prepared membranes that are shown in Fig. 1. Herein, polysulfone (PSF) membrane
demonstrated the characteristic asymmetric structure of dense top layer followed by
macro-voids. The loading of GO into the PSF polymer matrix has caused significant
changes in macro-void structure. Indeed, the hydrophilic basis of the GO is led to
extended porosity as well as changes in the macro-voids. As a result, the GO has
played an important role in modification of membrane morphology.
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aspect, leading to the higher permeability. The prepared composite with 0.067%
loaded GO showed double peak power densities compared to the pristine N212 in
direct formic acid, ethanol, and methanol fuel cells. The exact mass fraction of the
GO on the composite membranes was obtained to be 2.53 wt%. The well-aligned
thin top layer of GO contributed to the ideal fuel cell performance.
3 Characterization of Nanocomposite Membranes
The prepared nanocomposite membranes are characterized by various instrumental
methods to study the change in physiochemical properties and structure of the
membranes, which is caused by embedding GO or rGO into them. The Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), X-ray
Diffractometer (XRD), and Atomic Force Microscope (AFM) are typically used for
the morphology characterization, whereas X-ray Photoelectron Spectroscope (XPS)
and Fourier transform infrared (FTIR) spectroscope are commonly applied for functional group detection. Consequently, in order to study the effect of the surface
charge of the nanocomposite membrane, Zeta potential analyses are used. The contact
angle studies are employed to evaluate the surface hydrophilicity of the nanocomposite membranes. Thermogravimetric analysis (TGA) can also be used to measure
the weight loss and to detect the possible functionalized state of nanocomposite
membrane. At last, the mechanical stability of the membranes is measured by tensile
tests.
3.1 Membrane Morphology Analysis
(a) SEM Analysis
The cross-section morphologies and structure of the prepared nanocomposite
membranes are examined through SEM analyses. To make the membranes electrically conducting, the membrane samples are cut into small pieces and then
submerged in liquid nitrogen. Then sputtering of conductive metals (e.g. gold, platinum, cadmium, etc.) is used to coat on the cross-sectional layer. The acquisition
of cross-sectional images of the membranes is done in very high vacuum conditions [100–103]. Ganesh et al. [38] recorded the cross-sectional SEM images of the
prepared membranes that are shown in Fig. 1. Herein, polysulfone (PSF) membrane
demonstrated the characteristic asymmetric structure of dense top layer followed by
macro-voids. The loading of GO into the PSF polymer matrix has caused significant
changes in macro-void structure. Indeed, the hydrophilic basis of the GO is led to
extended porosity as well as changes in the macro-voids. As a result, the GO has
played an important role in modification of membrane morphology.