Direct Methanol Fuel Cell (DMFC) Abstract: Direct Methanol Fuel Cell (DMFC) is often considered as a promising electrochemical generator for various applications, including micro sources. Direct Methanol Fuel Cell or DMFCs are a subcategory of proton exchange fuel cell in which methanol is used as a fuel cell. There the main advantages are the ease of transport of methanol is used as a fuel, an energy density yet reasonable sustainable liquid at all environmental conditions. Efficiency is quite low for these cells, so they are targeted to especially to portable applications, where the energy and power density are more important than efficiency. Unfortunately, serious limitations are still remain and need to be solved before development of such devices. Challenges concern the various component of DMFC both anodic and cathodic reaction need more suitable electrodes, as well as the electrolytic membrane should be concerned. A Direct Methanol Fuel Cell (DMFC) works in the same way as a Polymer Electrolyte Membrane Fuel Cell (PEMFC) with a difference that methanol and water are split into protons. the low reaction kinetics of methanol oxidation reaction at anode. electrons and CO2 at the anode. the thickness of anode catalyst layer. . The efficiency is presently quietly low for these cells so they are targeted especially to portable applications. Now a days. Fuel cell can be classified according to working temperature: high. Phosphoric Acid Fuel Cell (PAFC). One of the most significant is that fact that methanol can be stored as a liquid over a wide temperature range (97℃ to 64. Liquid methanol on the other hand can be stored in cheap plastic containers and is an excellent carrier fuel that hydrogen can be extracted from to power fuel cells. fuel cell technology especially in DMFCs which is being for long as the most difficult fuel cell technology due to methanol crossover and catalytic inefficiency. Direct Methanol Fuel Cell (DMFC) is advantageous in terms of operation conditions as well as its reliability over the other types of fuel cells such as. Polymer Electrolyte Membrane Fuel Cell (PEMFC). an energy-dense yet reasonably stable liquid at all environmental condition. It works on the principal of oxidation reduction mechanism using special type of Polymer Electrolyte Membrane (PEM) which only allows proton to exchange through it. Molten Carbon Fuel Cell (MCFC). The main advantages are the ease of transport of methanol. medium and low (ambient) temperature system or referring to the pressure of operation: high. A thick catalyst layer increases the ohmic resistances as well as mass transfer resistances. Using methanol as primary fuel has its advantages over pure hydrogen. theoretical understanding of gas diffusion and fuel cell engineering. steady progress has been made such as catalysis. Solid Oxide Fuel Cell (SOFC).Abstract: Fuel cells are considered as future device for converting the chemical energy into electrical energy without having any movable parts. where energy and power density are more important than efficiency. medium and low (atmospheric) pressure system. Alkaline Fuel Cell (AFC). electrode structure. electrolysis.7℃) and therefore avoids many of the pitfalls of hydrogen storage. secondly. methanol can be produced from biomass or natural gas and the lack of complex steam reforming (used to generate hydrogen from fossil fuel) operations. The reasons behind the poor efficiency are firstly. such as low emission. caused by the mixed potential that is build between the parasitic cathodic methanol and the oxygen reduction . a potentially renewable liquid fuel with a high power dencity. and mobile power supplies. Abstract: Fuel Cells are electrochemical reactions that realized the direct conversion of chemical energy of reactants to electrical energy. like laptops. the cross over and the resulting loss of potential on the cathode . these type of fuel cell has several advantages. . Among the different fuel cell types. the DMFC with the polymer electrolytic membrane(PEM) as electrolyte and liquid water – methanol mixture as energy carrier is a promising power source of vehicular and various portable application. It is shown that this approach is predicted the harmful methanol flow across the polymer electrolyte membrane(PEM). Multimedia equipments.Abstract: Direct Methanol Fuel Cell (DMFC) is simulated in sequential mode in a zero dimensional mode to represent the electrochemical reaction on both electrodes.as well as fast and convenient refueling. However. The crossover of methanol lowers the system efficiency and decreases cell potential due to corrosion at the cathode. . where the electrochemical oxidation of methanol occurs. Most studies conclude that the reaction can proceed according to multiple mechanisms. it is widely accepted that the most significant reactions are the adsorption of methanol and the oxidation of CO. However. The kinetics of DMFCs are complicated because the reaction mechanism involves adsorption of methanol and several reaction steps including the oxidation of CO. Catalysis studies have attempted to analyze possible reaction pathways to find the main pathway of methanol oxidation. the reaction mechanism that will be used in to model performance of DMFCs.Abstract: Direct Methanol Fuel Cells(DMFCs)are currently investigated as alternative power source to batteries for portable applications because they can offer higher energy densities. two factors limit the performance of DMFC systems: crossover of methanol from anode to cathode and the slow kinetics of the electrochemical oxidation of methanol at the anode. longer times for use of laptop computers and more power available on these devices to support consumer demand. These carbon supported catalysts associate high metal surface area to a suitable concentration of the active phase that allows to maintain a low electrode thickness. These significant advantages make DMFCs an exciting development in the portable electronic devices market . methanol has a superior specific energy density (6000 Wh/kg) in comparison with the best rechargeable battery. Yet. increasing interest is devoted towards the miniaturization of these fuel cell devices in order to replace the current Li-ion batteries. respectively. . DMFC operation at low temperatures requires a high noble metal loading to enhance the kinetics of the methanol electro-oxidation reaction and counteract the poisoning effects at the cathode due to the methanol cross-over .Abstract: One of the most promising applications of Direct Methanol Fuel Cells (DMFCs) presently concerned with the field of portable power sources . Another significant advantage of the DMFC over the rechargeable battery is its potential for instantaneous refuelling. the present DMFC catalysts for low temperature applications are usually unsupported Pt and Pt-Ru alloys [10-12]. an 85% Pt-Ru (1:1 a/o) alloy supported on Vulcan XC-72 and a 60% Pt/Vulcan XC-72 were in-house prepared and utilized in DMFCs as anode and cathode catalysts. the presence of catalyst agglomeration effects in unsupported catalysts significantly limits their utilization in polymer electrolyte fuel cell systems. In this regard. In this work. mass transport and manufacturing problems deriving by the use of thick electrodes. lithium polymer and lithium ion polymer (600 Wh/kg) systems. Theoretically. In order to reduce ohmic drop. This means longer conversation times using mobile phones. This effect has been correlated to catalyst utilization and electro-catalytic activity at the different temperatures.Unfortunately. The influence of noble metal loading on the performance of a DMFC operating at low temperatures (30-60°C) has been investigated. The actual cell voltage of direct methanol fuel cell is less than theoretical voltage due to losses involved in the fuel cell operation. Moreover. For example. during the reaction process. The DMFC cells are fabricated by synthesizing Membrane Electrode Assembly (MEA). Methanol is oxidized to carbon dioxide at the anode. the methanol which has crossed over becomes ‘wasted’ and cannot be reused as a fuel in the anode side.Abstract: Direct methanol fuel cell (DMFC) is a device that converts chemical energy in Methanol to useful electrical energy. They combine with oxygen at the cathode to form water. reduces the efficiency of the DMFC as the carbon atoms in methanol poisons the cathode’s catalyst. Protons pass through the membrane and electrons through the external electrical circuit. This process known as methanol crossover (MC). some quantity of methanol permeates through the membrane from the anode side to the cathode. . Major losses are due to methanol cross over and slow reaction kinetics (activation losses). The proton conductivity and the methanol permeability of the PVDF-SPS membrane measured at 298 K . The surface compositions of the PVDF-SPS membrane were analyzed using X-ray photoelectron spectroscopy (XPS). The PVDF-SPS membrane has a stronger hydrophilic character than the pristine PVDF membrane and the polyvinylidene fluoridepolystyrene composite membrane (PVDF-PS). the composite membrane displays lower methanol permeability than the Nafion-117 membrane. denoted as PVDF-SPS.Abstract: The polyvinylidene fluoride-sulfonated polystyrene composite membrane with proton exchange performance. The complex formation of the composite membrane was ascertained by Fourier transform infrared spectroscopy (FTIR). The proton conductivity of the PVDF-SPS membrane was measured using impedance spectroscopy in the hydrated condition. Although PVDFSPS composite membrane possesses the lower oxidative stability than Nafion-117 membrane. The morphology of the composite membrane was characterized by environmental scanning electron microscopy (ESEM). The thermal stability of the PVDFSPS composite membrane was investigated using thermo gravimetric (TG) analysis. and the selectivity (the ratio of proton conductivity and methanol permeability) of the composite membrane is almost 20 times than that of Nafion-117. was prepared using a thermally induced polymerization technique. which is caused by the incorporation of sulfonic acid groups. .