Study of the variation of catalyst loading in cathode for SPEEK/CSMM membrane in direct methanol fuel cell (DMFC)

Variation of anode catalyst loading for modified sulfonated poly (ether ether ketone) (SPEEK) with charged surface modifying macromolecules (cSMM) membrane was studied, in order to get the higher performance in DMFC. The best optimal anode catalyst loading was 4 mgcm-2 for 30% Pt/Ru based on our previous result for this application. The modified SPEEK/CSMM membrane was characterized to ensure of its better performance in term of water uptake and methanol permeability. In cathode side, the effect of 5% and 10% Pd/C in 2,4 and 6 mgcm-2 of catalyst loading has been investigated with a fuel cell assembly. The preparation method of catalyst ink and membrane electrode assembly (MEA) was based on Dr. Blade method and hot pressing by using catalyzed diffusion media (CDM) method. The air flowrates were varied from 25-1000ml min-1, while 1M methanol concentrations, 1 ml min-1 of methanol flowrate and 60°C operating temperature were kept constant. These parameters were tested on the performance of single cell DMFC with 4 cm2 electrodes.The optimization catalyst loading will enhance the DMFC performance. It was found, the best optimal cathode catalyst loading was 4 mgcm-2 for 10% Pd/C with 4 mgcm-2 for 30% Pt/Ru in anode side for this application

Fabrication of nanocomposite membrane via combined electrospinning and casting technique for direct methanol fuel cell

Emergence of nanotechnology has resulted in the introduction of the electrospinning process in fabricating and characterising the polymer electrolyte membrane from the sulfonated poly (ether ether ketone) (SPEEK) nanocomposite membrane comprised of electrospun Cloisite15A® (e-spun CL) for direct methanol fuel cell (DMFC). Poly (ether ether ketone) polymer is sulfonated up to 63% by sulfuric acid. SPEEK63/e-spun CL nanofibers were fabricated via electrospinning in which SPEEK63 was used as carrier polymer while the SPEEK63/e-spun CL nanocomposite membrane was obtained by the casting method. Characterizations on physical, morphological and thermal properties of SPEEK63/e-spun CL were conducted and compared to the SPEEK membrane fabricated by casting simple mixing 2.5wt.% Cloisite15A® and 5.0wt.% triaminopyrimidine solution (SPEEK63/2.5CL/5.0TAP). Scanning electron microscopy (SEM) showed well electrospun Cloisite15A® with an average diameter nanofiber around 187.4 nm. Moreover, field emission scanning electron microscopy (FESEM) revealed that Cloisite15A® particles at a nanometer range were uniformly distributed and 66% smaller than those in SPEEK63/2.5CL/5.0TAP. Furthermore, x-ray diffraction proved that the dispersion state of Cloisite15A® fell into an intercalated phase. A very small amount of Cloisite15A® (0.05wt.%) in SPEEK63/e-spun CL successfully enhanced the proton conductivity up to 50%, whereas, unfortunately the methanol permeability value was 27 times higher than SPEEK63/2.5CL/5.0TAP. Proton conductivity and methanol permeability of SPEEK63/e-spun CL were 24.49 x 10-3 Scm-1 and 3.74 x 10-7 cms-1, respectively. Even though this study contributed to 95% selectivity lower than SPEEK63/2.5CL/5.0TAP, electrospinning showed a promising technique to further reduce original sized Cloisite15A® particles from mixed size (μm and nm) to nanometer sized. In addition, by fine tuning, the dispersion of Cloisite15A® enhances the SPEEK63/e-spun CL performance in DMFC

Carbon nanotubes based mixed matrix membrane for gas separation

Mixed matrix membranes (MMM) combine useful molecular sieving properties of inorganic fillers with the desirable mechanical and processing properties of polymers. The current trend in polymeric membranes is the incorporation of filler-like nanoparticles to improve the separation performance. Most MMM have shown higher gas permeabilities and improved gas selectivities compared to the corresponding pure polymer membranes. Carbon nanotubes based mixed matrix membrane was prepared by the solution casting method in which the functionalized multiwalled carbon nanotubes (f-MWNTs) were embedded into the polyimide membrane and the resulting membranes were characterized. The effect of nominal MWNTs content between 0.5 and 1.0 wt% on the gas separation properties were looked into. The as-prepared membranes were characterized for their morphology using field emission scanning electron microscopy (FESEM) and Transmission Electron Microscopy (TEM). The morphologies of the MMM also indicated that at 0.7 % loading of f-MWNTs, the structures of the MMM showed uniform finger-like structures which have facilitated the fast gas transport through the polymer matrix. It may also be concluded that addition of open ended and shortened MWNTs to the polymer matrix can improve its permeability by increasing diffusivity through the MWNTs smooth cavity

Study on synthesis and physical properties of charged surface modifying macromolecules with different end-capping materials for membrane applications

Polyol and end-capping agent were changed systematically when charged surface modifying macromolecules (cSMMs) were synthesized and characterized. Fourier transform infrared spectroscopy detected different degrees of hydrogen bonding interactions for different polyols and end-capping agents via shifting of absorption bands characteristic to the urethane group. Polyol of the lower molecular weight showed the stronger interaction and thus increased the cSMM's structural rigidity. The cSMM's rigidity increased from hydroxyl benzene sulfonate to hydroxyl propane sulfonate when poly(propylene glycol) was used as polyol. The effects of polyol and end-capping agent on the contact angle and water uptake were studied

High degree sulfonated poly(ether ether ketone) blend with polyvinylidene fluoride as a potential proton-conducting membrane fuel cell

Sulfonated poly(ether ether ketone) (sPEEK) membrane is a promising proton-conducting membrane for fuel cell. However, the performance and lifetime of sPEEK membrane depend on the degree of sulfonation (DS). High DS of sPEEK increases the performance, but the mechanical properties could deteriorate progressively which affect its lifetime. Thus, this study investigated the effect of adding polyvinylidene fluoride (PVDF) into high DS (80%) of sPEEK through solution blending method toward its physicochemical properties and morphology structures. The PVDF concentration was varied to 5, 10, 15, and 20 wt% relative to the sPEEK content. The existence of hydrophobic PVDF in 80% sPEEK improved the mechanical properties where the water uptake and swelling degree of membrane decreased, whereas the tensile strength increased. The sPEEK/PVDF 15 exhibited the highest proton conductivity (46.23 mS cm−1) at 80°C. Incorporating PVDF into high DS of sPEEK enhanced the mechanical properties which can be used as a proton-conducting membrane for fuel cell that may improve the performance and prolong the lifetime of the cell

Synthesis of nanostructured titanium dioxide layer onto kaolin hollow fibre membrane via hydrothermal method for decolourisation of reactive black 5

Hydrothermal method has been proven to be an effective method to synthesise the nanostructured titanium dioxide (TiO2) with good morphology and uniform distribution at low temperature. Despite of employing a well-known and commonly used glass substrate as the support to hydrothermally synthesise the nanostructured TiO2, this study emphasised on the application of kaolin hollow fibre membrane as the support for the fabrication of kaolin/TiO2 nanorods (TNR) membrane. By varying the hydrothermal reaction times (2 h, 6 h, and 10 h), the different morphology, distribution, and properties of TiO2 nanorods on kaolin support were observed by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). It was found that the well-dispersed of TiO2 nanorods have improved the surface affinity of kaolin/TNR membrane towards water, allowing kaolin/TNR membrane prepared from 10 h of hydrothermal reaction to exhibit the highest water permeation of 165 L/h.m2.bar. In addition, this prepared membrane also showed the highest photocatalytic activity of 80.3% in the decolourisation of reactive black 5 (RB5) under UV irradiation. On top of that, the kaolin/TNR membrane prepared from 10 h of hydrothermal reaction also exhibited a good resistance towards photocorrosion, enabling the reuse of this membrane for three consecutive cycles of photocatalytic degradation of RB5 without showing significant reduction in photocatalytic efficiency towards the decolourisation of RB5

Chemical degradation of SPEEK/CLOISITE/TAP membrane under fenton reagent accelerated strees test

The chemical degradation of SP/CL/TAP membrane had been studied using accelerated stress test (AST) to reduce the testing time for membrane degradation, The membrane was prepared using solution intercalation method. The membrane was immersed into Fenton Reagent solution (5% HzOz, 50 ppm FeS04) as a function of time in order to simulate the chemical radical attack on the membrane inside DMFC system. The commercial Nation 117 was used as reference membrane was found out that.the SP/CL/TAP membrane weight reduced by 6% after being Immersed in Fenton Reagent for 6 hours.FESEM image of the SP/CL/TAP and Nafion showed severed development of pinhole on the surface of the membrane after 6 hours of degradation. Both of the membrane showed similar proton conductivity deterioration behaviour SP/CL/TAP proton conductivity dropped from 5.76 x10-4 S/cm to 3.36 x10' 4 S/cm, while Nafion dropped from 7.46x10-4 S/cm to 5.20 x10-4 S/cm under 3 hours degradation testing and remained constant towards the end of the testing, This shows that the performance of the SP/CL/TAP membrane under DMFC severe degradation environment was found comparable to the commercial Nafion membrane. Thus, it can be concluded that the SP/CL/TAP membrane is a potential proton exchange membrane for long term usage in DMFC system

A Review on the fabrication of electrospun polymer electrolyte membrane for direct methanol fuel cell

Proton exchange membrane (PEM) is an electrolyte which behaves as important indicator for fuel cell’s performance. Research and development (R&D) on fabrication of desirable PEM have burgeoned year by year, especially for direct methanol fuel cell (DMFC). However, most of the R&Ds only focus on the parent polymer electrolyte rather than polymer inorganic composites. This might be due to the difficulties faced in producing good dispersion of inorganic filler within the polymer matrix, which would consequently reduce the DMFC’s performance. Electrospinning is a promising technique to cater for this arising problem owing to its more widespread dispersion of inorganic filler within the polymer matrix, which can reduce the size of the filler up to nanoscale. There has been a huge development on fabricating electrolyte nanocomposite membrane, regardless of the effect of electrospun nanocomposite membrane on the fuel cell’s performance. In this present paper, issues regarding the R&D on electrospun sulfonated poly (ether ether ketone) (SPEEK)/inorganic nanocomposite fiber are addressed

Efficient reduction of graphene oxide nanosheets using Na2C2O4 as a reducing agent

The efficient synthesis of reduced graphene oxide (RGO) nanosheets via chemical reduction process of exfoliated graphene oxide (GO) nanosheets was performed by introducing sodium oxalate (Na2C2O4) as a reducing agent. To study the effects of the reduction time on the synthesized RGO, the GO was reduced within -1/2, 1 and 2 h for RGO-1, RGO-2 and RGO-3, respectively. The C/O atomic ratio of the synthesized RGO-3 has increased from 2.16 to 6.32 after reduction as determined by X-ray photoelectron spectroscopy (XPS). The morphology analysis of the RGO-3 was determined by high-resolution transmission electron microscopy (HRTEM) almost revealed the formation of single layer. The number of RGO layers decreases as the time of the reduction increases. Based on these analysis results, sodium oxalate plays an important role in the efficient removal of the oxygen containing groups in the GO to produce high quality of RGO