Page - 71 - in Advanced Chemical Kinetics

Ethanol is inserted into the fuel cell, adsorbs at electrode surface and is oxidizedas shown in Figure8. CH3CH2OH!CO2þH2O (13) Whileoxygen fromair is reduced: O2 gð ÞþHþ aq þe�!H2O lð Þ (14) Which gives the overall reaction of the direct ethanol fuel cell (admitting complete ethanol oxidationreaction): CH3CH2OH lð ÞþO2 gð Þ!H2O lð ÞþCO2 gð Þþenergy (15) With the energy beingmostly electricalwork andheat. The electricwork is dependent on the potentialdifferencebetweencathodeandanode:thelargerthedifference,thebiggertheelectrical work. Redox kinetics, thus, influences this amount of energy conversions, by inducing the numberofelectronsthatare injectedintotheelectrical circuit, resulting inelectricalcurrent. At the anode, the ethanol adsorbs on electrode and the oxidation is characterized by the dehydrogenation. Some studieswith Fourier transformed infra-red (FTIR) in situ [32], differ- ential electrochemicalmass spectroscopy (DEMS) [33, 34] show that themainproducts from electrochemicalethanoloxidationreaction,onPt-basedcatalysts,areaceticacidandformalde- hyde [35]. The electricwork produced by direct ethanol fuel cell depends on the number of electrons that circulateat electrical circuit and thenumberof electronsgeneratedby the redox reaction.Thus, thekineticof ethanoloxidationreaction limits fuel cellperformance. Figure8. Schemeofdirect ethanol fuel cell. New Materials to Solve Energy Issues through Photochemical and Photophysical Processes: The Kinetics Involved http://dx.doi.org/10.5772/intechopen.70467 71