| Energy makes the world go around and global energy demand will continue to raise rapidly, so current energy sources are being used up at high rates due to the increase of the world's population, technical innovation and invention of machine. Petroleum is the world's most widespread fuel and is not a renewable. The increasing demand for gasoline and diesel fuel as a source of power makes the world more dependent on one source of energy which is becoming finite amount of fossil fuel on the earth. Also their burning is the leading cause of harmful greenhouse gas emissions and by continually using them, we are damaging our planet this is a worldwide concern. The world recognizes the importance of renewable energy for sustainable development, diversification of energy supply, and preservation of the environment so encourage continuing research and investment in renewable energy technology, throughout the world. The widespread use of hydrogen can reduce our dependence on fossil fuels and benefit the environment by reducing greenhouse gas emissions and criteria pollutant emissions that affect our air quality. Alternative sources such as geothermal, wind, hydrogen energy, solar, etc. will take on an increasingly large role in meeting the world's energy needs and the benefits it will offer not only for this generation, but for the many that will follow.Hydrogen is a promising energy carrier in part because it can be produced from different and abundant resources, including fossil, nuclear, and is renewable. Using hydrogen, particularly for our transportation needs, will allow us to diversify our energy supply with abundant, domestic resources. Fuel cells use hydrogen to create electricity, with only heat and water as byproducts. In addition, fuel cells unlike other technologies can use a variety of other fuels that can provide a source of hydrogen, such as biogas, methane, butane, etc.Polymer electrolyte membrane fuel cells(PEMFCs) are being investigated for use as low–power electrochemical energy conversion devices and have been looked as potential alternative energy conversion devices to conventional energy conversion systems such as combustion engines.The polymer electrolyte membrane plays a critical role in the overall performance of(PEMFCs). Nafion still remains as the most preferred PEM material, however; fuel cells running with Nafion® exhibit certain problem, such as inadequate water and heat management so its applicability is restricted by the abovementioned limitations. Consequently the development of novel electrolyte membranes with dense structure, good mechanical flexibility, and high proton conductivity with low relative humidity at temperatures above 100 °C remains an important challenge to the realization of practical PEM fuel cells. Lately, high temperature PEMFCs above 100 ?C have been proposed, as alternatives to low temperature PEMFCs, to solve such problems as catalyst poisoning by CO and fuel cell electrode flooding by liquid water, as well as to improve fuel cell efficiency.In this present work, to solve the technical difficulties existing in current high temperature PEM systems new fuel cell membrane materials based on polysulfones(PSF) functionalized with sulfonic acid group or with a highly polar, amphoteric and self–dissociative molecule(imidazole) via Polycondensations and Friedel–Crafts electrophilic substitution reaction have been designed, synthesized and investigated. Imidazole is a highly polar compound, its structure contains both a proton donor(NH) and a proton acceptor(N :), and in recent times has been investigated as a potential for high temperature anhydrous solventPSF are high performance thermoplastics with excellent chemical, mechanical and thermal properties. Recently these polymers are frequently modified to obtain proton conducting membrane materials intended for use in fuel cells, especially at temperatures above 100°C.In both case the functional group(ionic sites) were separated from the polymer back bone and were concentrated to side chain. By means of isolating the ionic sites on side chains, away from the polymer main chain, the nanophase separation between the hydrophobic and the hydrophilic domains of the prepared membrane may be influenced, which in turn may provide membranes with balanced water sorption characteristics.Several techniques were used to characterize prepared membrane. Spectroscopic and thermal characterizations are two important techniques used to gather information fully evaluate the structural properties, functionality and the adequacy for application as fuel cell electrolytes. Fourier Transform Infrared(FTIR) and Nuclear Magnetic Resonance(NMR) were employed to provide structural and compositional characterizations of the prepared membrane. Other characterization techniques employed include; TGA, SEM, AFM, mechanical testing etc. and membrane was found to be effective for high electrical conductivity as well as mechanical strength.Under anhydrous circumstances, impedance spectroscopy data show the ionic conductivity of the membrane hit the highest point value of 7.94 10–3 at 140 °C related with the activation energy of 11.6 kJ mol-1 for proton transport. So the modification of these materials resulted in proton conductivities and thermal stabilities in the range of other direct sulfonated aromatic materials however the modification of membrane still needed to improve the membrane performance,... |
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