Papers by Keyword: Direct Methanol Fuel Cell (DMFC)

Abstract: This study reports the effect of plasticizers namely isopropanol, polyethylene glycol, maltitol and spermidine on the properties of the sodium alginate composite membrane. The concentration of each potential plasticizer was set at minimum to execute performance. Properties of sodium alginate were studied through characterization studies - Field Emission Scanning Electron Microscope (FESEM) to observe on the morphology structure. The membrane performance is also seen through water uptake and swelling ratio tests. Isopropanol produced better plasticizer with the lowest water uptake of 575.53% and less hydrophilic compared to spermidine (1268.46%), polyethylene glycol (1014.30%) and maltitol (595.82%). Further study may require copolymerization to support polyol for ensuring structure firmness. This study proven the plasticizers could enhance membrane’s flexibility in DMFC and becoming a promising choice of additives for better alginate-based membrane establishment.

Abstract: In this study, a fine fibers mat were produced from SPEEK/Cloisite solution and the effect of the dope concentration on the fibers morphology was performed.The electrospun fibers were denoted as e-spunCL and fabricated as dense membrane (SP/e-spunCL) by immersing electrospun fibers into half-solidified SPEEK solution The fiber’s mechanical stability study was also conducted. The fibers diameters and morphology were observed by using Scanning Electron Microscopy (SEM).While the mechanical properties of the fibers was observed via tensile strength test. The results showed that as the concentration increased (0.05 wt%, 0.10 wt%, 0.17 wt%, 0.25 wt% and 0.30 wt%), the fibers diameters become larger which varies from 9.257 μm to 495.4 nm. The highest tensile strength among all fibers was recorded from SP/e-SpunCL17 which was found to be 19.96882±1.49458MPa. SP/e-spunCL17 showed the most promising physico chemical properties with the highest water uptake and proton conductivity of 25.87±1.9827 %, 12.12±0.2837 mScm^-1 and the lowest methanol permeability with 1.22±0.3748 x10^-8 cm²s^-1.

Abstract: The objective of this study is to investigate the morphology effect of ENR-50 content on the conductivity and methanol permeability of SPEEK/ENR-50 membranes for DMFC application. Three different ratios (9.5:0.5, 8.5:1.5 and 7.5:2.5) of blended SPEEK/ENR-50 membranes were prepared via solution intercalation method. The cross sectional images of the all SPEEK/ENR-50 membranes studied by SEM shows an existence of ENR-50 droplets in SPEEK matrix which decrease in size with an increasing of ENR-50 content from 1.5 wt% to 2.5 wt%. The study of the performances of the blended membranes shows that the proton conductivity and methanol permeability of the membranes decrease with an increasing of ENR-50 content. However, the proton conductivity of the blended membrane with 0.5 wt% ENR-50 content (9.66x10^-3 S cm^-1) proven higher than pristine SPEEK but lower than Nafion 117. The barrier performance of all SPEEK/ENR-50 membranes was enhanced compared to the expensive Nafion 117 membrane and pristine SPEEK. Consequently, by incorporating ENR-50 content into SPEEK membrane, the selectivity of the membranes has considerably increased.

Abstract: Novel electrocatalysts from iron phthalocyanine (FePc) and polyindole (PID) supported on carbon nanotubes (CNTs) have been synthesized for oxygen reduction reaction (ORR) in Direct Methanol Fuel Cell (DMFC). Two synthetic strategies have been proposed: i) preparation of PID on CNTs (PID/CNTs) through indole polymerization followed by the mechanical mixing of PID/CNTs with FePc (FePc_PID/CNTs); and ii) dispersion of polymerized PID, FePc, and CNTs in methanol and subsequent drying (FePc/PID/CNTs). The morphology of prepared catalysts was examined by SEM, and the electrochemical activity towards ORR was evaluated by cyclic voltammetry. FePc/PID/CNTs catalysts were found to have higher activity than that of FePc_PID/CNTs, due to a better dispersion of PID and FePc on carbon support, as demonstrated by SEM. Furthermore, in comparison with platinum on carbon black the prepared PID-based catalysts exhibited a stable ORR potential in both H₂SO₄ and H₂SO₄ + CH₃OH solution. These new iron-based catalysts are thus promising to substitute platinum/carbon black at the cathode side of DMFC.

Abstract: A composite anode was investigated with the aim of enhancing the performance of direct methanol fuel cells (DMFCs). Fine iridium oxide nanoparticles were synthesized by a sulfite complex method. These IrO₂ nanoparticles were mixed by sonication with a 50% PtRu/C catalyst prepared by the same procedure, considered as benchmark anode catalyst. A significantly higher performance was recorded for the composite electrode compared to the bare one based only on PtRu/C. The results confirm that the electrocatalytic activity is related to the characteristics of water displacement of the additive, evidencing that a multifunctional catalyst can operate better than PtRu for methanol oxidation since this multi-step process requires different functionalities to speed up the reaction rate.

Abstract: Direct Methanol Fuel Cells (DMFCs) have been postulated as suitable systems for power generation in the fields of portable power sources, remote and micro-distributed energy generation, and auxiliary power units (APU). The main objective of the DURAMET project ((http://www.duramet.eu) is to develop cost-effective components for DMFCs with enhanced activity and stability in order to reduce stack costs and improve performance and durability. The project concerns with the development of DMFC components for application in auxiliary power units and portable systems.

Abstract: In this paper, proton conducting composite membranes of Nafion®-mordenite for direct methanol fuel cell (DMFC) were prepared using solution casting method. Mordenite, used as inorganic filler, was incorporated into Nafion polymer in order to improve membrane properties for DMFC application. Effect of solution casting temperature on resulting composite membranes was focused. The temperature of the membrane preparation was varied from 80 to 120°C. Properties and morphology of the resulting membranes including solubility, water uptake, ion – exchange capacity were investigated and reported. It was found that composite membrane prepared at 100°C gave the most alcohol resistance and mechanical stability membrane with 0.59% soluble. Furthermore, it gave highest ion – exchange capacity, 0.10 meq⋅g^-1, which is 33% and 98% higher than the membranes prepared at 80°C and 120°C respectively.

Abstract: Zirconium hydrogen phosphate / sulfonated poly (arylyene ether) s composite membranes has been prepared and evaluated by the unit cell test for direct methanol fuel cell (DMFC) applications. The comparison between the performances of zirconium hydrogen phosphate/ sulfonated poly (arylyene ether) s composite membranes and Nafion 115 shows that the unit cell performance with composite membrane was superior to that of Nafion, which makes zirconium hydrogen phosphate/ sulfonated poly (arylyene ether) s composite membrane a potential candidate for direct methanol fuel cells.

Abstract: Abstract. Performance of direct methanol fuel cell (DMFC), using polymer composite membrane, can be directly affected by membrane properties, including permeability, proton conductivity and membrane thickness. In order to obtain high DMFC performance, methanol permeability of the membrane should be low, while keeping high proton conductivity. This may be achieved by modification of incorporating inorganic filler into high proton conducting membrane. In this work, the analytical modeling for DMFC performance prediction was developed to be a guideline for Nafion based membrane improvement. Methanol permeability and proton conductivity were set at 0.30 – 5.60 cm²×S^-1 and 0.08 – 0.15 S×cm^-1 with the thickness of 25 – 1000 μm. The results show that DMFC performance strongly depends on the methanol permeability especially with thin membrane giving maximum power density of 1034 and 100mW×cm^-2 at the permeability of 0.30 and 5.60 cm²×S^-1, respectively, with thickness of 45 μm, while with thick membrane the permeability has negligibly effect. However, the proton conductivity mainly affects DMFC performance only with thick membrane as a result of ohmic resistance.

Abstract: Tungsten carbide nanofibers for the anode catalyst of direct methanol fuel cells (DMFCs) were prepared from the precursor nanofibers with the diameter around 250 nm using an electrospinning technique. The electrospun nanofibers from the mixture of ammonium metatungstate and polyvinylpyrrolidone were dried and calcined in air at 700 °C to form tungsten oxide nanofibers, and reduced in 20 vol.% CH₄/H₂ atmosphere at 700 °C for 2 h. Surface morphology and crystalline structure of the prepared nanofibers were investigated using FE-SEM and XRD. The methanol oxidation reaction (MOR) activity of the prepared samples was evaluated by cyclic voltammetry (CV). The FE-SEM and XRD analyses showed that beaded nanofibers of tungsten carbide were successfully obtained. The WC nanofiber electrocatalyst exhibited a MOR activity suggesting it can be a candidate of the catalyst for DMFC. The presence of impurities, carbon and tungsten oxide, which may affect the activity, were detected at the surface.