98
9 Hydrogen Fuel Cells and Nanotechnology
But the better proton conductivity than the Nafion membranes was only depicted by
ZrO 2 sol–gel composite. This can be related to the higher acidity of zirconia-based
sol–gel nanocomposite membranes as compared to the similar membranes of Ti and
Si. The results of thermal gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) showed superiority of nanocomposite membranes over pristine Nafion
membraned in terms of glass transition temperature and decomposition [18].
Marianne et al. have employed SiO 2 nanoparticles for modification of Nafion
115 membranes. The prepared membranes were used to analyze the water sorption
effect, effective mobility of proton, concentration of proton, and conductivity of
proton. The membranes were prepared by sol–gel process. The silica nanoparticles
were loaded in the range of 5.9–33.3 wt.% in the Nafion membranes. The density of
the membranes was found to be in reverse relation with the silica content, and also the
composite membranes depicted small dimensional changes with swelling in water,
hence supporting the theory of rigid scaffolding formation within the membrane.
The retention of the water increases with the increased loading of nanoparticles
because of void formation in the membrane. Greater concentration of water in the
membrane lowers the concentration of proton, hence reducing the conductivity of
proton. Increased silica content resulted in decreased mobility of proton (this can be
associated to enhanced tortuosity of the proton-conduction passage) also contributing
to the reduction in conductivity of proton [19].
In another work, covalently interlinked nanocomposite hydroxide ion transporting
membranes were fabricated on quaternized polysulfone and modified graphene oxide
support. Fourier transform infrared attenuated total reflection spectroscopy (FTIRATR) and transmission electron microscopy (TEM) characterization were used to
analyze the structure and morphology of the fabricated membranes. Different properties of the membrane like water sorption, swelling proportion, ionic conductivity,
and mechanical strength were determined. The prepared nanocomposite membrane
with functionalized graphene oxide content of 2% was found to be flexible and
tough. The membrane depicted 19.44% water sorption and 1.27 × 10
−2 S cm
− 1
ionic conductivity at 60 °C and 14.90 MPa [20].
In an investigation, polybenzimidazole nanocomposite membranes doped with
phosphoric acid and integrated with inorganic nanoparticles were fabricated. The
polybenzimidazole polymer was integrated with varying amounts of different inorganic fillers like titanium dioxide, silicon dioxide, and zirconium phosphate (an inorganic proton conductor) followed by the doping of phosphoric acid. This resulted
in the formation of high-temperature proton exchange membrane fuel cells. The
fabricated membranes were analyzed for acid sorption and acid leaching abilities,
mechanical strength, impedance analyses, and chemical stability in NN dimethylacetamide (DMAc). TGA characterization confirms enhanced thermal stability of the
prepared membranes. The inorganic fillers were found to enhance the acid retention
ability of the membranes. Electrochemical impedance spectroscopy (EIS) demonstrated that the integration of 5 wt. % ZrP or 5 wt. % SiO 2 enhances the conductivity of proton. However, the nanocomposite membrane integrated TiO 2 showed low
conductivity values than pure polybenzimidazole membrane. The poor performance
of the TiO 2 is associated to its non-uniform structure. The highest conductivity of
9 Hydrogen Fuel Cells and Nanotechnology
But the better proton conductivity than the Nafion membranes was only depicted by
ZrO 2 sol–gel composite. This can be related to the higher acidity of zirconia-based
sol–gel nanocomposite membranes as compared to the similar membranes of Ti and
Si. The results of thermal gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) showed superiority of nanocomposite membranes over pristine Nafion
membraned in terms of glass transition temperature and decomposition [18].
Marianne et al. have employed SiO 2 nanoparticles for modification of Nafion
115 membranes. The prepared membranes were used to analyze the water sorption
effect, effective mobility of proton, concentration of proton, and conductivity of
proton. The membranes were prepared by sol–gel process. The silica nanoparticles
were loaded in the range of 5.9–33.3 wt.% in the Nafion membranes. The density of
the membranes was found to be in reverse relation with the silica content, and also the
composite membranes depicted small dimensional changes with swelling in water,
hence supporting the theory of rigid scaffolding formation within the membrane.
The retention of the water increases with the increased loading of nanoparticles
because of void formation in the membrane. Greater concentration of water in the
membrane lowers the concentration of proton, hence reducing the conductivity of
proton. Increased silica content resulted in decreased mobility of proton (this can be
associated to enhanced tortuosity of the proton-conduction passage) also contributing
to the reduction in conductivity of proton [19].
In another work, covalently interlinked nanocomposite hydroxide ion transporting
membranes were fabricated on quaternized polysulfone and modified graphene oxide
support. Fourier transform infrared attenuated total reflection spectroscopy (FTIRATR) and transmission electron microscopy (TEM) characterization were used to
analyze the structure and morphology of the fabricated membranes. Different properties of the membrane like water sorption, swelling proportion, ionic conductivity,
and mechanical strength were determined. The prepared nanocomposite membrane
with functionalized graphene oxide content of 2% was found to be flexible and
tough. The membrane depicted 19.44% water sorption and 1.27 × 10
−2 S cm
− 1
ionic conductivity at 60 °C and 14.90 MPa [20].
In an investigation, polybenzimidazole nanocomposite membranes doped with
phosphoric acid and integrated with inorganic nanoparticles were fabricated. The
polybenzimidazole polymer was integrated with varying amounts of different inorganic fillers like titanium dioxide, silicon dioxide, and zirconium phosphate (an inorganic proton conductor) followed by the doping of phosphoric acid. This resulted
in the formation of high-temperature proton exchange membrane fuel cells. The
fabricated membranes were analyzed for acid sorption and acid leaching abilities,
mechanical strength, impedance analyses, and chemical stability in NN dimethylacetamide (DMAc). TGA characterization confirms enhanced thermal stability of the
prepared membranes. The inorganic fillers were found to enhance the acid retention
ability of the membranes. Electrochemical impedance spectroscopy (EIS) demonstrated that the integration of 5 wt. % ZrP or 5 wt. % SiO 2 enhances the conductivity of proton. However, the nanocomposite membrane integrated TiO 2 showed low
conductivity values than pure polybenzimidazole membrane. The poor performance
of the TiO 2 is associated to its non-uniform structure. The highest conductivity of